Stratolaunch Aircraft Touches Down After Its ﬁ Rst ﬂ Ight

Home , Artemis 3, Dornier Flugzeugwerke, Handley Page, Hybrid Air Vehicles, LightSail, Paris Convention of 1919

TRAJECTORIES 96 AEROPUZZLER 8 LOOKING BACK 94 Robot maker What does this plane need? Goddard’s moon treatise and more

2019Y E A R IN R E V IEW

Artemis INCLUDING PAGES 16, 42, 45, 61-64, 67, 72, 75

DECEMBER 2019 | A publication of the American Institute of Aeronautics and Astronautics | aerospaceamerica.aiaa.org LAUNCHING THE FUTURE OF SPACE

From launch to landing, Boeing’s CST-100 St a r line r, one of the nation’s first commercial space capsules, is paving the way for the new space age. Follow us to experience the journey.

boeing.com/starliner YEAR IN REVIEW | December 2019 MORE AT aerospaceamerica.aiaa.org B:11.125” T:10.875” S:10”

Astronauts Christina Koch, left, and Jessica Meir made history in October when they made the ﬁ rst all-female spacewalk. Page 75. NASA

ON THE COVER Stratolaunch, the world’s largest aircraft by wingspan, ﬂ ew for the ﬁ rst time in April. THE YEAR Pages 4, 33, 36. IN REVIEW The most important developments as described by AIAA’s technical, integration and outreach committees

aerospaceamerica.aiaa.org | DECEMBER 2019 | 1 24–26 AUGUST 2020 NEW ORLEANS, LA

CALL FOR PAPERS The AIAA Propulsion and Energy Forum is the world’s only event that showcases both aeronautics and space propulsion as well as energy technologies at a single venue.

AIAA IS SOLICITING PAPERS FOR THE 2020 FORUM IN THE FOLLOWING TECHNICAL DISCIPLINES: › Additive Manufacturing for Propulsion Systems › Hybrid Rockets

› Advanced Integrated Intelligent Propulsion › Inlets, Nozzles, and Propulsion Systems Controls Integration

› Advanced Mechanical Components › Liquid Propulsion

› Advanced Propulsion Concepts › Nuclear and Future Flight Propulsion

› Advanced Vehicle Systems › Pressure Gain Combustion

› Aerospace Power Systems › Propellants and Combustion

› Electric Propulsion (Spacecraft) › Propulsion Education

› Energetic Components and Systems › Small Satellites

› Energy Conversion Technology › Solid Rockets

› Energy-Efficient and Renewable Energy › Thermal Management Technology Technologies › Unmanned Aircraft Systems: Propulsion, Energy, › Fuel and Power Generation Technology and Applications

› Gas Turbine Engines › AIAA/IEEE Electric Aircraft Technologies Symposium (26–28 August) › High-Speed Air-Breathing Propulsion

SUBMIT AN ABSTRACT BY 11 FEBRUARY 2020 aiaa.org/propulsionenergy/cfp YEAR IN REVIEW AEROSPACE★ ★ ★ ★ ★ ★ AMERICA

DECEMBER 2019, VOL. 57, NO. 11 Adaptive Structures...... 9 Materials ...... 11

EDITOR-IN-CHIEF Aeroacoustics ...... 19 MVCE...... 27 Ben Iannotta Aerodynamic Decelerator Systems ...... 31 Microgravity and Space Processes ...... 59 [email protected] Aerodynamic Measurement Technology ...... 20 Modeling and Simulation ...... 28 ASSOCIATE EDITOR Aerospace Power Systems ...... 45 Multidisciplinary Design Optimization...... 12 Karen Small Aerospace Trafﬁ c Management ...... 69 Non-Deterministic Approaches ...... 13 [email protected] Air Transportation Systems...... 32 Nuclear and Future Flight Propulsion ...... 53 STAFF REPORTER Cat Hofacker Aircraft Design ...... 33 Plasmadynamics and Lasers...... 29 [email protected] Aircraft Operations ...... 34 Pressure Gain Combustion ...... 54

EDITOR, AIAA BULLETIN Applied Aerodynamics ...... 21 Propellants and Combustion ...... 55 Christine Williams Astrodynamics...... 22 Sensor Systems and Information Fusion...... 43 [email protected] Atmospheric Flight Mechanics ...... 23 Small Satellite...... 60 EDITOR EMERITUS Balloon Systems ...... 35 Society and Aerospace Technology...... 75 Jerry Grey CFD Vision 2030 ...... 70 Software Systems ...... 44 CONTRIBUTING WRITERS Communications Systems ...... 40 Solid Rockets...... 56 Robert van der Linden, Computer Systems ...... 41 Space Architecture ...... 61 Debra Werner, Frank H. Winter Design Engineering ...... 10 Space Automation and Robotics...... 62

John Langford AIAA PRESIDENT Electric Propulsion ...... 46 Space Exploration...... 72 Daniel L. Dumbacher PUBLISHER Energetic Components and Systems ...... 47 Space Logistics ...... 63 Rodger S. Williams DEPUTY PUBLISHER Energy Optimized Aircraft Systems...... 71 Space Resources ...... 64

ADVERTISING Flight Testing ...... 36 Space Systems ...... 65 [email protected] Fluid Dynamics...... 24 Space Tethers ...... 66 Gas Turbine Engines...... 48 Space Transportation ...... 67 ART DIRECTION AND DESIGN Ground Testing ...... 25 Spacecraft Structures ...... 14 THOR Design Studio | thor.design Guidance, Navigation and Control...... 26 Structural Dynamics...... 15

MANUFACTURING AND DISTRIBUTION High-Speed Air-Breathing Propulsion ...... 49 Structures ...... 16 Association Vision | associationvision.com History ...... 74 Survivability ...... 17 Hybrid Rockets ...... 50 Systems Engineering ...... 18 LETTERS AND CORRESPONDENCE HyTASP ...... 37 Terrestrial Energy Systems ...... 57 Ben Iannotta, [email protected] Inlets, Nozzles and Propulsion Systems ...... 51 Thermophysics ...... 30 Intelligent Systems...... 42 Transformational Flight ...... 73 Life Sciences and Systems ...... 58 V/STOL Aircraft Systems ...... 39 Lighter-Than-Air Systems ...... 38 Weapon System Effectiveness ...... 68 Liquid Propulsion ...... 52

Aerospace America (ISSN 0740-722X) is published monthly except in August by the American Institute of Aeronautics and Astronautics, Inc., at 12700 Sunrise Valley Drive, Suite DEPARTMENTS 200 Reston, VA 20191-5807 [703-264-7500]. Subscription rate is 50% of dues for AIAA members (and is not deductible therefrom). Nonmember subscription price: U.S., $200; 4 Editor’s Notebook foreign, $220. Single copies $20 each. Postmaster: Send address changes and subscription orders to Aerospace 5 Letters America, American Institute of Aeronautics and Astronautics, at 12700 Sunrise Valley Drive, Reston, VA, 20191-5807, Attn: A.I.A.A. Customer Service. Periodical postage 7 Flight Path paid at Reston, Virginia, and at additional mailing offi ces. Copyright 2019 by the American Institute of 77 AIAA Bulletin Aeronautics and Astronautics, Inc., all rights reserved. The name Aerospace America is registered by the AIAA in the U.S. Patent and Trademark Offi ce. 92 Career Opportunities 8 AeroPuzzler 94 Looking Back An unsatisfactory test fl ight poses a question. Do you have the answer? 96 Trajectories

aerospaceamerica.aiaa.org | DECEMBER 2019 | 3 EDITOR’S NOTEBOOK 2020 VISION

The Stratolaunch aircraft touches down after its ﬁ rst ﬂ ight. Unfinished business Stratolaunch

his year displayed a tantalizing mix of technical breakthroughs, human achievements and also vulnerability. Six months after the death of its sponsor, billionaire Paul G. Allen, the Stratolaunch aircraft became the largest plane (by wingspan) ever to fl y when pilots lifted off from Mojave Air and Space Port in California. TThe video is amazing, but wowing us isn’t why Allen, the Microsoft co-founder and self-proclaimed “Idea Man,” formed Stratolaunch Systems Corp. eight years ago. He wanted to prove that satellite launch costs could be slashed by carrying launch vehicles and satellites to an altitude of 35,000 feet and boost- ing them from there. This would prepare the way for “world-altering” satellite applications, to use the company’s words. Still unclear is whether the Stratolaunch fl ight was the start of a new way of business or something that will be remembered as an engineering feat with little long-term signifi cance, akin to the fi rst fl ight of Howard Hughes’ Spruce Goose in 1947. The company issued a dryly worded statement in October saying it had “transitioned ownership” to a person or entity it did not name. In another case of unfi nished business, neither of NASA’s Commercial Crew contractors managed to launch a crew to the International Space Station this year. SpaceX’s uncrewed launch to ISS and Boeing’s pad abort test, deemed acceptable by NASA, suggest that 2020 could be the year we see this achievement. And of course there is the matter of the Boeing 737 MAX aircraft and the accidents that killed 346 people. As of this writing, the FAA had yet to bless an update to the Maneuvering Characteristics Augmentation System anti-stall software and the planes remained grounded. I believe it will take more than the MAX aircraft returning to fl ight in 2020 to achieve closure on this issue. An independent panel of some kind should be convened with the gravitas and authority of the Rogers commission that examined the space shuttle Challenger accident or the Columbia Accident Investigation Board. The many engineering, business and regulatory lessons from this saga should be recorded for those in business today and for posterity. ★

Ben Iannotta, editor-in-chief, [email protected]

4 | DECEMBER 2019 | aerospaceamerica.aiaa.org LETTERS TO THE EDITOR Reactions to “Mystery sightings”

really enjoyed the “Mystery of the ‘Damn on-board, could not survive the G-forces unless the craft offered no inertia. That would Things’” article [November cover story]. I be a nice trick to obtain. I was interested when news broke a couple i Data tends to imply one craft reached orbital speed while it was fl ying near the ground, of years ago and was wondering what happened up to Mach 20. Another nice trick! For those with knowledge about hypersonics, the heating since then. Great reporting. would be so severe to stress our known expertise where the survival of the craft would probably Michael Martin, AIAA senior member exceed temperatures above tens of thousands of degrees Fahrenheit. This craft must have generated a lot of thermal energy. In all of these events, there were no gas dynamic shocks or waves. That by itself pushes the credibility of conventional wisdom. have read a lot of material about these i One craft moves underwater at speeds of more than several hundreds of miles per hour. Navy pilot incidents, and this is one of the The best technology that we can establish underwater at high speed involves cavitating I best treatments I have seen. I especially torpedoes that move on the order of 150 mph, none of which can perform underwater appreciated the succinct critiques of various maneuvers because the saltwater dynamic pressure would easily destroy the structure. This theories, as well as the quotes from some tech- UFO craft seems to be invulnerable to such effects. nical experts not previously heard from on this These events demonstrate technologies beyond our competence. We should not be subject in anything I’ve read. afraid of unknown knowledge that potentially offers us embryonic technologies which There was one paragraph, however, that would exceed our imagination pinioned by the conventional wisdom. Instead, we, espe- bothered me a tad. Your use of the term “con- cially in academia, should spend signifi cant and serious efforts to accept and develop this spiracy theories” has a somewhat pejorative game-changing expertise and its promise to benefi t humankind as we try to touch the stars. ring. The genesis of UFO theories in the late P.A. Murad, AIAA associate fellow, Vienna, Virginia, [email protected] 1940s and 1950s was that a hell of lot of people were seeing the “damn things,” including a ** “A n Electromagnetic Rocket Stellar Drive....Myth or Reality? Part I- Electromagnetic and Relativistic Phenomenon,” July 1995. great many military personnel (up to generals), “A n Electromagnetic Rocket Stellar Drive....Myth or Reality? Part II- Fluid Dynamic Interactions and especially at nuclear sites, as well as commercial an Engine Concept,” July 1995 pilots, private aviation pilots, knowledgeable people like Kelly Johnson* , and other credible witnesses. As for the CIA’s claim that U-2 fl ights accounted for many UFO sightings, this has been refuted in detail by various researchers, including veteran UFO skeptic Robert Sheaffer and UFO photoanalyst Bruce Maccabee. That aside, commendations on a solid piece of journalism on a thorny topic. Douglas D. Johnson, Adelphi, Maryland [email protected]

*Clarence “Kelly” Johnson founded Lockheed Skunk Works and provided a UFO account to the U.S. Air Force’s “Project BLUE BOOK” report.

n the 1990s, I gave two AIAA papers** involving UFOs based upon concurrent I information and available photographs. The Aerospace America article was quite thorough and informative, especially about broaching speculations of Russian and Chi- nese capabilities, but did not address several important pieces of interest for engineers and scientists. i At least one craft went from high to low altitudes within seconds and performed unusual maneuvers. Conventional wisdom implies biological beings, if they were

aerospaceamerica.aiaa.org | DECEMBER 2019 | 5 5–7 MAY 2020 LAUREL, MD

COMPETE, DETER, AND WIN: Innovation at the Speed of Relevance

Leaders from government, military, industry, and academia will gather to advance and accelerate aerospace defense modernization, informed by the Office of the Under Secretary of Defense for Research and Engineering’s priorities. This Secret/NOFORN event will use the National Defense Strategy as a framework to discuss the strategic, programmatic, and technical topics and policy issues pertaining to the aerospace and defense community.

Program Highlights › Accelerating Technology Transition › Advanced Technology: Industry Prime Contractors Panel › AI-Enabled Autonomy › Leveraging Innovation to Advance Missile Defense › Technological Overmatch: The Critical Role of DoD Labs and DARPA › USD R&E Enterprise

Trusted Autonomous Systems Course This ITAR-restricted course, to be held after the forum on 8 May, aims to provide a foundation for evaluating trust in autonomous systems. State-of-the-art research, methods, and technologies for achieving trusted autonomous systems will be reviewed with current applications.

The Future of Autonomous Flight: The Technology Clock Ticks On

y family immigrated to the United States in the mendous progress toward addressing the challenges, a remark late 1800s in pursuit of the American dream. by NASA Administrator Charlie Bolden at the 2013 AIAA AVI- Leaving the European system of dictated standing ATION Forum hints at our biggest challenge. He commented of wealth, they dreamed of a land where they that he would like to see the aviation community more active, could come from nothing and become anything. noting “If I got half the pressure from this community that I MThe dynamic system of America offered hope that the fruits of get from one Congressman on going to a distant planet, we’d their aspirations and hard work could be harvested. be OK.” His comment strikes at the heart of the speedbump My generation was raised during the Cold War with an eye to realizing the full potential of autonomous flight: we lack on the Doomsday Clock counting down to the man-made global a common intent. catastrophe of nuclear war or climate change. Our nation was Realizing the full potential of uncrewed and autonomous in a technology-driven race to prevent the existential threat flight is a shared responsibility of government, academia, to our life, our liberty, and our dreams. The space race was infrastructure providers, operators, manufacturers, and the inspiration for my career in aerospace. suppliers. Our community must come together to engage With the end of the Cold War, the threat receded and a new policymakers to assure they understand what must be done, one emerged. In his 30 April 1992 speech to the Aero Club what is at risk, and what R&D and infrastructure investments of Washington, D.C., Mr. A. D. Welliver, CTO of The Boeing must be made to complete the foundation for uncrewed and Company, introduced a new clock, the Technology Clock. This autonomous flight. clock represented our economic security and a countdown to The unifying strength of our members’ shared values and the loss of U.S. leadership in aerospace. their technical leadership roles uniquely position AIAA to bring A quarter of a century later, we are in an era of technology the stakeholders together. These values include: disrupters to our society, the aerospace community, and the global balance of power. A tipping point offering the promise i Collective and Collaborative Capabilities: There is strength of societal as well as environmental benefits is occurring from and reason in diverse disciplines. the confluence of social trends, technological advancements, i Knowledge Excellence: Intellectual pursuit requires education and military and commercial interests. and learning to expand upon current thought. Uncrewed and autonomous flight provides an example i Challenge and Excitement in the Work: We desire to make of the confluence of disruptive technologies which, in their a difference. infancy, are already providing social and economic benefits. i Honor and Achievement: We must promote the value of the Delivery of medical supplies to remote areas, search and profession to the public. rescue, and remote monitoring of critical infrastructure are i Future Vision: We believe in the importance of what we do, only a few examples. I look forward to the day I can fly over and that there is ever more work to be done. Seattle’s congested traffic! The technical challenges to building this future include As the Doomsday and Technology Clocks march toward creating a safe transition for these vehicles into the operation midnight, imagine the day where a rising nation announces of the airspace system, and defining the regulatory framework that they have tethered an uncrewed vehicle to their latest for replacing the current human-centric pilot and controller fighter. Then imagine how the balance of power begins to shift. functions. The implementation of a regulatory foundation The price for losing our technical leadership will be high: for emerging technologies requires 1) a clear framework and loss of jobs, a declining economy, and a shift in the balance of classification for the apportionment of risk to the aviation power. We must start the conversation with policymakers on system components for the varying degrees of automation vs how this generation will come together to drive the confluence autonomous learning systems, 2) clarity of the contribution of of technology disruptors to address societal concerns and to deterministic systems (the machine) and non-deterministic assure the dream is passed to the next. ★ systems (the pilot) to safety, 3) clarity of the safety level required for various degrees of autonomy and for new technologies, and 4) validation of the methods used to ensure compliance. James Vasatka While our members and key stakeholders have made tre- Member, AIAA Board of Trustees

aerospaceamerica.aiaa.org | DECEMBER 2019 | 7 Do you have a puzzler to suggest? Email us at [email protected].

Flight-test FROM THE NOVEMBER ISSUE CANARD CONUNDRUM: We asked whether Ra- fale ﬁ ghters and NASA’s X-59 low boom design have canards for the same reason. NASA’s Mark Guynn feedback and Clint Balog of Embry-Riddle Aeronautical University helped us select the winning response:

Q. After landing, a test pilot says the WINNER: False. The Dassault-built Rafale fi ghter is a two-surface airplane which utilizes the canard for pitch stability and control. The X-59 is a prototype jet was dif cult to control three-surface airplane and uses the canard to redistribute the lifting surface in certain con gurations and wanted area for the purpose of reducing the sonic boom made during supersonic fl ight. Most aircraft’s wings create lift aft of the aircraft’s center of gravity to stall sooner than it should. He (CG) which results in a negative moment. Therefore, an additional lifting assesses “a Cooper-Harper of 7 to surface is required to balance the moments in the pitch-axis. In conventional aircraft, a tail is used to create negative lift and a positive moment. In the 8” at times. One of the engineers case of the Rafale fi ghter, the trailing-edge of the wing is already at the back of the plane. The designers utilize a lifting surface forward of the CG to sighs: “Well, it was worth a shot, but balance the moments to maintain pitch stability while giving controllability in we’d better put them back on.” What the pitch-axis with changing the canard’s incident angle. devices is the engineer most likely The three-surface design utilized by the X-59 allows the wing to be smaller due to the canard providing lift. Also, the canard helps reduce the size of referring to, and why would it be the horizontal tail because the forward-of-CG lifting surface would require desirable to leave them off? a smaller aft lifting surface to balance the moments. By redistributing the cross-sectional area of a wing and tail along the fuselage, the designers may be able to achieve a quieter sonic boom. Loud sonic booms are a result of shock waves building up from different surfaces of an airplane. By redis- Draft a response of no more than 250 tributing the cross-sectional area, the shock wave buildup can be reduced. words and email it by midnight Dec. 9 Royd Johansen to [email protected] for a chance to AIAA member San Jose, California have it published in the January issue. Johansen is an aeronautical engineer for Northrop Grumman.

For a head start ... nd the AeroPuzzler online on the rst of each month at https://aerospaceamerica.aiaa.org/ and on Twitter @AeroAmMag .

8 | DECEMBER 2019 | aerospaceamerica.aiaa.org AEROSPACE DESIGN AND STRUCTURES

Materials that remember show promise direct harvesting of solar energy without drawing system electrical power. To increase the stiffness of for aircraft and space applications the solar array, new SMPC-based structures were studied this year toward the goal of a second round BY DARREN J. HARTL of fl ight testing, according to the authors. A number of new wind tunnel demonstrations of The work of the Adaptive Structures Technical Committee enables aircraft and spacecraft to adapt to changing environmental conditions and aeronautical adaptive structures applications were mission objectives. also performed this year. To quantify for the fi rst time experimentally the acoustic benefi t of an SMA slat cove fi ller in transport aircraft, researchers from Texas A&M University and NASA’s Langley Research Center in Virginia deployed a new aeroacoustic wind tunnel at Texas A&M in February and recorded a 2 decibel noise reduction at 20 meters/second on a 6.25% scale wing model. An international team from Boeing, Deharde, the European Transonic Morphing missiles Windtunnel and Langley demonstrated a new wind being explored by the tunnel testing paradigm allowing airplane models U.S. Air Force Research to be actuated in a cryogenic wind tunnel, even Laboratory would adjust their shapes in fl ight to given small model feature sizes. The test article provide aerodynamic consisted of a 4.5% scale Boeing-787 half-model benefi ts. Such concepts with control surfaces powered by fully integrated are enabled by novel SMA rotary actuators. In August, the model was actuator designs and ew applications of shape memory materials tested at cryogenically simulated fl ight Reynolds morphing skins. U.S. Air Force Research Laboratory were demonstrated worldwide this year, number conditions. Another collaborative project while new morphing structural concepts initiated this year by the University of Maryland, were tested in new ways. University of Bristol and Intelligent Automation Inc. Boeing and NASA’s Glenn Research with NASA support demonstrated the feasibility of a NCenter in Ohio tested shape memory alloys, or camber morphing wing prototype. The prototype SMAs, that could be incorporated into the composite consisted of multimaterial 3D-printed morphing materials that form the components of deployable skins supported by a 3D-printed bioinspired fl exure. structures on commercial airplanes. These SMA The prototype’s 60-centimeter camber morphing compositions would respond autonomously to section was actuated in a 24 m/s free jet wind tunnel ambient temperature changes. The new NASA- with minimal fl utter. Upscaling and fl ight tests are Boeing SMAs were incorporated into the hinge of a planned for future phases. deployable vortex generator that was fl ight-tested Regarding noncommercial applications of on a Boeing 777-200 in November as part of the adaptive structures, in September, the Aerospace company’s ecoDemonstrator program. The vortex Systems Directorate of the Air Force Research generator retracts at cruise to reduce drag. Laboratory first demonstrated a multiphysical At the same time, Texas A&M University research- “dry tunnel” that creates a simulated aerother- ers worked with University of British Columbia to mal test environment for morphing missiles. The develop SMA artifi cial muscle actuators mimicking approach gives researchers uninterrupted access the functionality of characterized bird muscles. Re- to the structurally adaptive test article during sults were fi rst presented publicly in May, showing simulated flight testing for full field strain and that SMA components can act as actuators, brakes temperature tracking and allows testing of various and structural components under cyclic stimuli, missile articulation mechanisms across a range of emulating avian muscle functions. speed and altitude conditions not achievable in In July, the Harbin Institute of Technology in traditional wind tunnels. China revealed the existence of an experimental University of Central Florida researchers funded satellite that tested a prototype shape memory by the U.S. Navy’s Offi ce of Naval Research this year polymer composite for self-deploying solar arrays, explored transient fl uid-structure interactions or SMPCs. In a paper in the journal Smart Materials during sea-based air vehicle morphing to find and Structures, the designers of the experiment, optimal confi gurations for modular high-stiffness called Mission SMS-I, described the mission as structures. The researchers measured the unsteady the fi rst SMPC demonstration in geostationary forces on a twisting and bending compliant wing orbit. The authors said they have proved that their via water towing tank experiments, validating the carbon-reinforced SMPC can deploy solar arrays by concept and enabling new modeling approaches. ★

aerospaceamerica.aiaa.org | DECEMBER 2019 | 9 AEROSPACE DESIGN AND STRUCTURES

Novel designs and NASA’s moon-to-Mars goals inspire next generation BY LISA SAAM

The Design Engineering Committee promotes the development and dissemination of technologies that assist design engineers in deﬁ ning practical aerospace products.

low-lunar orbit to the surface. Refueling capabilities are required for the elements of the landing system to be reusable. NASA conducted ground testing on fi ve full- size prototypes of deep-space habitation modules. The testing began in March and lasted sever- irbus in July released the conceptual design A bird-of-prey-inspired al months. The prototypes were made by Bigelow for a new airliner that it said would push design that Airbus says Aerospace of Nevada, Boeing, Lockheed Martin, the boundaries of technology and innova- will motivate the next Northrop Grumman, and Sierra Nevada Corp. generation of aeronau- tion with its birdlike appearance. Revealed of Colorado between 2016 and 2018. During the A tical engineers to create on the opening day of the Royal International Air sustainable aircraft. ground testing, NASA evaluated human factors Tattoo air show in the United Kingdom, the design Airbus such as how astronauts would live and work in the was dubbed the Bird of Prey due to its wing and tail Gateway and the ergonomics and capabilities of structures that mimic those of an eagle or falcon. SpaceX’s DEMO-1 Crew each habitat. A major objective of the prototype Dragon autonomously Other unique design features include moveable docked with the Interna- testing was to produce a refi ned set of design re- wingtips inspired by feathers, a next-generation tional Space Station in a quirements for deep-space habitation modules. hybrid electric propulsion system, distributed profi rst for a U.S. commercial In March, a SpaceX Crew Dragon docked au- pulsion and components that would be 3D-printed spacecraft. The spacecraft tonomously with the International Space Station from state-of-the-art materials. Subscale technol- is shown in the hangar at in a demonstration mission, called DEMO-1, with- Launch Complex 39A in ogy demonstrators could incorporate elements of out a crew aboard. The docking was the fi rst by an Florida. this concept, but the main goal was to inspire the SpaceX American commercial spacecraft at ISS and the next generation of aeronautical engineers to help fi rst space launch under NASA’s Commercial Crew create sustainable and greener aircraft. Program. Crew Dragon leverages the fl ight heritage In the space realm, NASA made several awards of Dragon, which completed 16 cargo missions to in May with the objective of achieving a human and from ISS prior to the DEMO-1 mission. Crew lunar landing by 2024. Maxar Technologies of Col- Dragon consists of a pressurized capsule with en- orado received a contract from NASA to design the vironmental control and life support equipment Power and Propulsion Element of NASA’s lunar capable of carrying up to seven passengers and an Gateway. The PPE will be a solar electric propul- unpressurized trunk for cargo. sion spacecraft that will also serve as a communi- In the small satellite launcher market, Virgin Or- cation relay for the Gateway. bit of California in July conducted the fi rst drop test Also, 11 companies in eight states were awarded of its LauncherOne rocket, a milestone toward its contracts under NASA’s Next Space Technologies fi rst orbital launch. In the test, an inert LauncherOne for Exploration Partnerships. The awardees will was dropped from the Cosmic Girl carrier aircraft, a conduct studies or produce prototypes of poten- modifi ed Boeing 747, over the test range at Edwards tial human landing spacecraft, with a focus on de- Air Force Base in California’s Mojave Desert. For a scent, transfer and refueling. The transfer portion space launch, Cosmic Girl will carry a LauncherOne will carry astronauts from the Gateway to low-lunar rocket to an altitude above 30,000 feet and release it orbit. The descent portion will transport them from to boost small satellites to orbit. ★

10 | DECEMBER 2019 | aerospaceamerica.aiaa.org AEROSPACE DESIGN AND STRUCTURES

costs of space vehicle thermal protection systems. All fi ve ultraperformance thermoplastics were able to withstand aerothermal testing at a heat fl ux of 100 watts per square centimeter for as long as 30 seconds without disintegrating. Based on thermogravimetric analysis char yield results, Kepstan 7002 PEKK has the highest char yield of 64% and ULTEM 9085 has the lowest char yield of 43%. High char yield usually indicates material has good ablation performance. In addition to experimental study, computational fl uid dynamics analyzed the heat transfer between the specimens under various Unique material innovations reduce scenarios compared with material response obtained experimentally. costs in manufacturing In February, Nanoarmor LLC and the U.S. Naval BY TERRISA DUENAS AND ED GLAESSGEN Research Laboratory manufactured 70% dense The Materials Technical Committee promotes interest, understanding zirconium carbide composites using additive and use of advanced materials in aerospace products where aerospace manufacturing. These ultra-high-temperature systems have a critical dependency on material weight, multifunctionality ceramics, or UHTC, offer superior properties that and lifecycle performance. enable their use in leading edges and engine components in extremely high-temperature platforms. A sample of 3D- his year the Massachusetts Institute of Tech- Existing refractory ceramics do not offer adequate printed ultraperformance nology and Metis Design Corp. collaborated mechanical and thermal properties to handle ex- thermoplastic polymer to demonstrate an “out-of-oven” composite treme environments. Furthermore, corresponding (upper right) was heated curing process that addresses the limitations manufacturing methods cannot yield customizable by an oxyacetylene torch (center) and of conventional oven- and autoclave-based and cost-effective leading-edge components for photographed over the Tprocesses. Those drawbacks include poor energy high-performance aerospace systems. The Nanoar- course of 30 seconds. The effi ciency, high operational cost, long cure times mor-Naval Research Lab technique produced inex- post-test pyrolysis zone and geometrical constraints on the components to pensive UHTC zirconium carbide ceramic matrix (top) and charred surface be cured. In August, the team demonstrated carbon composites with nanostructured reinforcements (bottom) are shown on the left side. nanotube heaters for conductively curing composite that maximize density, hardness and durability KAI LLC structures without an oven, achieving equivalent under high temperatures and mechanical stress. thermophysical and mechanical performance to The polymer-based reaction bonding synthesis conventionally cured composites, while reducing route yields net shape carbides, nitrides and cure time by 60% and energy consumption by two borides from compressed powder mixtures of metal orders of magnitude. The team believes that this precursors and carbon-rich resins with high char process contributes to the design and manufacturing yields. In addition, the approach is pressureless of next-generation multifunctional architectures by and incorporates a one-step reactive melt infi l- leveraging nanoengineered laminate capabilities tration process that converts preceramic mixtures such as sensing, structural health monitoring and into dense custom forms at 1,400 degrees Celsius. ice protection systems. The approach is signifi cantly less expensive than In July, KAI LLC, the University of Texas at Austin, existing alternatives. They reinforced the ceramic RMIT University of Melbourne, Australia, Arkema matrix composites with metals, fi bers, nanocarbons Inc. and Western Washington University collabo- and secondary ceramic phases in order to improve rated on a study to utilize high-temperature fused their mechanical strength, thermal conductivity, fi lament fabrication technologies to manufacture and resistance to oxidation and ablation. Blends fi ve unique ultraperformance polymers: SABIC PEI of these precursor materials with polymer binders ULTEM 9085, Roboze PEEK, Smart materials 3D into suspensions with controllable viscosities un- PEEK, Arkema Kepstan 7002 PEKK and a modifi ed lock capabilities for inexpensive rapid prototyping PEI (ULTEM 1010) material. These can be used in of customized shapes with tunable dimensions, low-heat-fl ux spacecraft application. The goal of geometries and properties. ★ the research was to develop a class of materials and additive manufacturing processes that could one day Contributors: Boris Dyatkin, Joseph H. Koo and substantially reduce the manufacturing and assembly Brian L. Wardle

aerospaceamerica.aiaa.org | DECEMBER 2019 | 11 AEROSPACE DESIGN AND STRUCTURES

Developers unveil new optimization tools propulsor for NASA’s STARC-ABL confi guration, short for Single-aisle Turboelectric Aircraft with and system designs an Aft Boundary-Layer propulsor. Throughout the year, OpenMDAO was used as a platform to build BY DOUGLAS ALLAIRE, JOHN HWANG AND GIUSEPPE CATALDO several new analysis tools and libraries with analytic The Multidisciplinary Design Optimization Technical Committee provides a derivatives. OpenAeroStruct and OpenConcept are forum for those active in development, application and teaching of a formal aircraft design tools developed by the MDO Lab at design methodology based on the integration of disciplinary analyses and the University of Michigan; pyCycle is a propulsion sensitivity analyses, optimization and artifi cial intelligence. modeling library developed by NASA’s Glenn Re- search Center in Cleveland; Dymos and Ozone are he year saw important advancements at the two ordinary differential equation integration and intersections of multidisciplinary design optimal-control libraries. Dymos was developed optimization and machine learning. by Glenn and Ozone was developed by the Large- In January, the University of Central Scale Design Optimization Lab at the University of Florida released an open-source imple- California, San Diego. Tmentation of physics-informed neural networks. The year also saw important advances in The work extends recurrent neural networks to system design. In April, there was the fi rst fl ight cumulative damage models and empowers users of an unmanned vehicle testbed designed and to merge physics-informed and data-driven layers built by a team from the Massachusetts Institute within one deep neural network. of Technology, University of Texas at Austin, Texas In March, the University of Michigan MDO Lab A&M University and Boeing’s Aurora Flight Sciences. made available its suite of tools for aerodynamic The vehicle is being used to demonstrate the use of shape optimization, MACH-Aero, with two different reduced modeling and machine learning methods computational fl uid dynamics solvers, ADfl ow and for dynamic data-driven mission replanning. The OpenFOAM. The University of Michigan MDO Lab reduced models also form the basis for a digital also created Webfoil, an application with airfoil data, twin of the vehicle, which MIT is developing with analysis and optimization. Akselos. In June, the University of California, San Diego, In August, Virginia Tech in collaboration with Multiscale Multiphysics Design Optimization Lab DK Schmidt and Associates developed approaches The ADfl ow computational fl uid released an open-source implementation of effi - to embed dynamics and control of aircraft with dynamics solver enables cient large-scale 3D topology optimization for highly fl exible wings into design environments the aeropropulsive coupled heat transfer and mechanical stress as well used to perform multidisciplinary analysis and analysis and design as coupled fl uid structure interaction. This paves design optimization of transport aircraft. Re- optimization of the the way to design highly effi cient heat-dissipating NASA STARC-ABL searchers demonstrated that bioinspired internal aircraft confi guration. and load-carrying lightweight aerospace structures. structural layout using curvilinear spars and ribs Two color maps are NASA’s OpenMDAO, an open-source high- could reduce the structural weight for composite shown: pressure performance computing platform for systems fl ying-wing aircraft. coe cient at the analysis and multidisciplinary optimization, V2.8, Also in August, in collaboration with ISAE- surface and normalized was released in June. Later in the year, OpenMDAO stagnation pressure at SUPAERO and MIT, NASA’s Goddard Space Flight the symmetry plane. V2.8 was used to solve a set of fi rst-of-their-kind Center in Maryland completed the structural analysis University of Michigan MDO Lab design optimizations of a boundary layer ingestion module of a multidisciplinary design optimization framework. This framework was applied to the analysis of the James Webb Space Telescope where it was demonstrated that a multifidelity approach can drastically reduce analysis cycles for global sensitivity analyses. In June, the Multifi delity Modeling in Support of Design and Uncertainty Quan- tification workshop brought together 40 researchers and practitioners to discuss multifi delity modeling challenges and opportunities and to highlight the progress of multifi delity methods combining physics-based models and machine learning for design optimization and uncertainty quantifi cation. ★

12 | DECEMBER 2019 | aerospaceamerica.aiaa.org AEROSPACE DESIGN AND STRUCTURES

Airmen lower an engine from a C-5M Super Galaxy cargo jet for maintenance at Dover Air Force Base, Del. More e cient tools developed by the non-deterministic approaches community are maximizing the service life and safety of jet engines. U.S. Air Force

optimization. These new methods enable com- Researchers advance probabilistic putationally effi cient implementations of robust optimization to ensure safe, effi cient designs. analysis for greater effi ciency and safety Fleet managers and regulators rely on probabilistic risk analysis to make sure their systems continue BY ANDREW OLLIKAINEN to maintain safety throughout their service life. The Non-Deterministic Approaches Technical Committee advances the art, Broader application of these models relies on effi cient science and cross-cutting technologies required to advance aerospace modeling of material failure. In July, researchers from systems with non-deterministic approaches. the University of Illinois at Urbana-Champaign and École Nationale Supérieur de Mécanique et d’Aero- ext-generation aerospace systems aim for technique, Poitiers, France, began an analytic study greater effi ciency and safety. However, the of structural material deterministic and stochastic ever-growing complexity of aerospace sys- failure criteria. Their work focuses on reducing the tems brings increased test costs. Alternatives dimensionality of material failure analysis under to traditional, hardware-focused testing complex loading. Nare crucial to the cost-effectiveness of developing Following the in-service failure of a commercial new technologies for fl ight. This presents signifi cant jet engine in 2018, the non-deterministic approach- challenges due to the presence of uncertainties es community has been engaged in supporting all and increasingly expensive-to-evaluate simulation sectors of the aviation enterprise as it addresses the models. unique challenges of engine sustainment. In May, In January, the AIAA Certifi cation by Analysis Southwest Research Institute of Texas released a soft- Community of Practice chartered an international ware package to support the probabilistic damage team of representatives from industry, academia tolerance methodology required by the upcoming and governmental agencies to establish formal FAA Advisory Circular AC33.70-5 for FAA certifi cation guidelines for applying virtual flight modeling risk assessment of axial blade slots in aircraft engine to reduce the burden of fl ight-testing. Among the disks containing random manufacturing-induced areas of focus are model verifi cation and validation anomalies. The methodology was implemented methods and uncertainty quantifi cation analysis. in the DARWIN probabilistic damage tolerance Multifi delity methods that enhance information software (developed by SwRI). The software was with cheaper lower-fi delity information sources are created under the guidance of an industry steering key to making design optimization under uncertainty committee composed of major international aircraft computationally feasible. In January, researchers gas turbine engine manufacturers. Released to the from the multifi delity, multi-information source, steering committee for review in May, the software multiphysics, or M3, team led by the Massachusetts will be available to licensed users in early 2020. In Institute of Technology under the U.S. Air Force July, as part of a joint contract with the U.S. Air Multidisciplinary University Research Initiative Force Research Laboratory and the Probabilistic introduced active learning methods through mul- Analysis Consortium for Engines, SwRI completed tifi delity Effi cient Global Reliability Analysis. In a multiyear project to develop new probabilistic July, M3 introduced a novel Monte Carlo variance methods and tools for assessing uncertainty in reduction method via the Information Reuse for turbine engine component life prediction in the Importance Sampling in reliability-based design presence of limited data. ★

aerospaceamerica.aiaa.org | DECEMBER 2019 | 13 AEROSPACE DESIGN AND STRUCTURES

Deployable structures expand the L3Harris Technologies also announced that it has begun constructing its 100th deployable mesh capabilities of small satellites refl ector antenna. This 12-meter-diameter folded rib refl ector will be used in a European mission to BY MARK SILVER measure biomass and carbon in forests around the world and is scheduled to launch in 2022. While The Spacecraft Structures Technical Committee focuses on the unique challenges associated with the design, analysis, fabrication and testing of this milestone is an important one for L3Harris, it spacecraft structures. is also an important milestone for the deployable structures community because it demonstrates how, with continuous development over the past 50 years, deployable spacecraft structures have become much more widely accepted by the greater satellite industry. Elsewhere in the industry, in March DARPA launched MMA Design’s 2.25 m-diameter Pan- tograph Deployed High Gain Reflectarray, or P-DaHGR, on the Radio Frequency Risk Reduction Deployment Demonstration satellite. P-DaHGR, developed and built at MMA’s Colorado facility, offers high-performance, scalable RF capabilities, from UHF to Ka-band, that are specifi cally designed for small-satellite missions. The refl ect array technology can provide equivalent to performance to more complex, parabolic-shaped dishes for missions that do not require large bandwidths. The use of high-strain composite deployable mechanisms, which have thin composite materials that can be rolled or folded, continued to accelerate over the past year. In June, Roccor’s HSC drag sail known as ROCFall was launched on the General Atomics Orbital Test Bed satellite. ROCFall, developed and built at Roccor’s Colorado facility, will be used to deorbit the satellite at the conclusion of its operations in order to meet the 25-year low Earth orbit lifetime guidelines. Also in June, the crowd-funded LightSail-2 Artist’s rendering of s the role of small satellites in commercial, spacecraft from the Planetary Society was launched L3Harris’ 5-meter-diam- research and government missions con- from NASA’s Kennedy Space Center in Florida. eter High Compaction tinues to grow, deployable structures are LightSail-2 is a 32-square-meter solar sail that uses Ratio antenna. The design scales from a 1-meter- further expanding their capabilities. New the energy of incident solar photons to provide a diameter dish that fi ts small satellite capabilities that deployable propulsive force. While solar sail propulsion was into a cubesat volume Astructures have enabled include high-gain antennas, fi rst demonstrated in 2010 by the Japan Aerospace to the 5-meter-diameter accelerated deorbit and solar sail propulsion. Exploration Agency’s IKAROS interplanetary dish shown here, which The year began with L3Harris Technologies mission, LightSail-2 is the fi rst demonstration of in stowed form takes up one-tenth of a cubic of Florida introducing a new generation of high- solar sail propulsion in low Earth orbit. meter, a fraction of a accuracy, large-aperture small satellite antennas In August, assembly of NASA’s James Webb small-satellite volume. called the High Compaction Ratio, or HCR, refl ec- Space Telescope was completed at Northrop L3Harris tor antenna. HCR ranges from a 1-meter refl ector Grumman’s California factory. The fi nal assembly and feed that fi ts in a 20-by-10-by-10-centimeter step involved joining the Spacecraft Element and volume suitable for cubesat applications, to a 5-m Optical Telescope Element/Integrated Science refl ector that packages in less than a quarter of an Instrument Module or OTIS. Once additional Evolved Expendable Launch Vehicle Secondary tests are completed and Webb unfolds in space Payload Adapter class satellite. The HCR refl ector following its 2021 launch, it will be the largest antenna is designed for high-frequency, high-gain space telescope and the fi rst deployable space performance of up to 40 gigahertz. It enables a fast telescope. ★ production turnaround to support small satellite constellation development. Contributors: Phil Henderson and TJ Rose

14 | DECEMBER 2019 | aerospaceamerica.aiaa.org AEROSPACE DESIGN AND STRUCTURES

the wingtips to be unlocked during fl ight, before the Flapping fl ight breakthrough and demonstrator, based on the manufacturer’s A321 plane, is scaled up further. other advances Turning to launch vehicles, in April the NASA BY NATHAN FALKIEWICZ AND D. TODD GRIFFITH Engineering Safety Center examined the applicability The Structural Dynamics Technical Committee focuses on the interactions of QSMA, short for Quasi-Static Modal Analysis, for among a host of forces on aircraft, rocket and spacecraft structures. modeling nonlinear structural dynamic behavior. As an alternative to direct integration of the non- he year saw major developments in the struc- linear equations of motion, QSMA determines the tural dynamics discipline across industry, dependence of frequency and damping on response national labs and academia. amplitude using loading behavior from nonlinear In the field of airplane design, Alba- static analyses. QSMA was exercised on a nonlinear trossOne, a remote-controlled aircraft made model of test hardware developed for NASA’s Orion Tby Airbus in collaboration with United Kingdom Multi-Purpose Crew Vehicle program. Excellent This Orion European universities including Bristol, fl ew for the fi rst time agreement was observed between the reduced and Service Module test in February. AlabtrossOne is a scale demonstrator full-order nonlinear models, encouraging future article was used to with unique in-fl ight, fl apping wingtips that could employment of QSMA to support accurate and demonstrate application revolutionize wing design. The engineers developed effi cient model reduction of structures with bolted of Quasi-Static Modal what they call a “semiaeroelastic hinge” concept to joint nonlinearities. Analysis to a complex, large-scale aerospace reduce drag and overall wing weight, while combating In August, the University of Texas at Dallas, in structure. the effects of turbulence and wind gusts. The team collaboration with the University of Virginia, Na- NASA plans to conduct further testing including allowing tional Renewable Energy Laboratory, University of Colorado at Boulder, Colorado School of Mines and University of Illinois at Urbana-Champaign, completed installation of a one-fi fth-scale demonstration rotor for a new offshore wind turbine concept at NREL’s National Wind Technology Center. The full- scale design is a two-bladed, coned, downwind rotor concept with 105-meter blades and rated power of 13.2 megawatts. A key feature of the UT-Dallas structural design is that the subscale 21-m blades are designed having scaled stiffness, structural dynamics and loads (including gravitational, centrifugal and thrust) properties of the full-scale design matched at subscale. This broad set of scaling requirements, which is in addition to strict structural safety design requirements, made this demonstrator design novel and challenging. The team is focused on initial fi eld testing to validate the structural, aerodynamic and aeroelastic performance characteristics of the new concept rotor along with new control strategies for loads reduction. In the area of unmanned aerial systems, researchers from the University of Kentucky who are in the VibroAcoustics Consortium made measurements close to the surface of a hovering UAS and developed a process for predicting sound pressure levels at any distance from the UAS. In addition, U.K. researchers performed pass-by noise tests on UAS that may eventually serve as a basis for standardized measurements. Results were demonstrated to be repeatable to within 1 decibel. UAS noise has been identifi ed as resulting primarily from the blade pass frequency and harmonics. Mitigation approaches for noise reduction of the primary source may take several forms including blade design, operational optimization and structural design. ★

aerospaceamerica.aiaa.org | DECEMBER 2019 | 15 AEROSPACE DESIGN AND STRUCTURES

team developed a companion code, SwiftComp, as Structures tested; modeling developed constitutive modeling software for virtual structures BY HARRY H. HILTON and materials testing, as well as for executing fi nite element analysis codes for effi cient, high-fi delity com- The Structures Technical Committee works on the development posite material modeling. This year, the MSG project and application of theory, experiment and operation in the design developed an MSG-based multiscale Timoshenko of aerospace structures. model, an effi cient and accurate multiscale method Boeing for predicting failure envelopes that uses MSG-based thermo-viscoelastic multiscale modeling and AI-assisted, MSG-based multiscale modeling. Arizona State University continued developing a computationally effi cient multiscale modeling framework for nanoengineered composites. With support from the Offi ce of Naval Research, investigators studied material behavior across multiple length scales while quantifying analysis uncertainty. These efforts in nanotechnology led to the fabrication and application of carbon nanotube-enhanced carbon fi ber reinforced polymer composites and nanoengineered novel architectures (such as radially grown fuzzy fi ber composites). This approach was used to characterize elevated-temperature mechanical Boeing in January n July, NASA demonstrated that the Orion space- properties of thermosets reinforced with randomly released an illustration craft launch abort system can jettison astronauts dispersed carbon nanotubes. of its latest design for to safety during launch emergencies. The test was GKN Fokker and Gulfstream continued to assess the Transonic Truss- another milestone for the Artemis program, which is thermoplastic composites as primary aircraft Braced Wing aircraft it I is collaborating on with dedicated to sending Americans back to the moon and structures. High out-of-plane strength and sustain- NASA. eventually to Mars. During the test, a representative ability/recyclability are some of the thermoplastic Orion crew module was launched from Cape Canaveral advantages. Efforts to develop cost-effective man- on a modifi ed Peacekeeper missile built by Northrop ufacturing technologies continue across the globe Grumman. The test version Orion experienced max- — particularly in the Netherlands. imum expected high-stress aerodynamic loadings, Boeing continued to refine the design of the traveled to a 6-mile (9.7-kilometer) altitude and reached proposed hypersonic, passenger-carrying airliner it Mach 1.3 when the planned abort sequence triggered. unveiled at the 2018 AIAA Aviation Forum in Atlanta. In June, NASA began structural testing of the It is similar to an uncrewed hypersonic surveillance largest component for the United States’ new deep and reconnaissance concept the company presented space rocket, the Space Launch System, at NASA’s in January; both have a general delta-wing confi gu- Marshall Space Flight Center in Alabama. The ration with dual rear fi ns, streamlined fuselage and liquid hydrogen tank, which is 64.6 meters tall and sharp nose. The vehicle could travel at up to Mach has a diameter of 8.4 m, comprises two-thirds of 5 and cross the Atlantic and Pacifi c oceans in two the rocket’s core stage, and it holds, at minus 217 and three hours, respectively, Boeing said. degrees Celsius, the approximately 2 million liters of Boeing made public its newest Transonic Truss- supercooled liquid hydrogen necessary to power the Braced Wing design in January at the AIAA SciTech RS-25 engines. During those tests, which wrapped Forum in San Diego. Researchers say this aircraft up in September, dozens of hydraulic cylinders in would fl y higher and faster than the previous TTBW a 66-meter-tall test stand pushed and pulled the concepts. Originally, the TTBW was designed to fl y tank, subjecting the test article to the same stresses at Mach 0.70 to Mach 0.75; engineers modifi ed the endured during liftoff and fl ight. design for more aerodynamic effi ciency while fl ying The Mechanics of Structure Genome project at at Mach 0.80. By adjusting the wing sweep angle, Purdue University continued its ongoing multiscale the resulting optimized truss can more effi ciently modeling effort that seeks to provide a new, unifi ed carry lift, thus allowing designers to increase the approach to modeling composite anisotropic heterog- wingspan to 51.8 m with a folding wing concept. enous structures. MSG simplifi es multiscale composite The integrated design is expected to increase the modeling by determining and executing only necessary aircraft’s cruise speed. ★ analyses to suffi ciently capture the relevant physics. MSG also provides a rigorous yet effi cient approach Contributors: Siddhant Datta, Zhenning Hu, to handling complex buildup structures. The Purdue Bruce D. Willis, Michael Wolff and Wenbin Yu

16 | DECEMBER 2019 | aerospaceamerica.aiaa.org AEROSPACE DESIGN AND STRUCTURES

1000 aircraft at the Landing and Impact Research Facility in Virginia. The aircraft was released from a height of 31 meters with signifi cant vertical and horizontal velocities. The primary objective of the test was the generation of full-scale crash data in support of proposed FAA aircraft crashworthiness guidelines. Secondary objectives included the evaluation of effects on standard and advanced crash test dummies designed for increased biofi delity and with enhanced instrumentation. Reducing laser damage, acquiring The effects on these anthropomorphic test devices, or ATDs, depended on the seat-to-fl oor load paths aircraft crashworthiness data and structural deformation, which was measured by onboard sensors and photogrammetric techniques. BY AMEER G. MIKHAIL, BRIAN J. BARLOW AND JASON A. SAWDY Langley researchers developed a 3D model of the The Survivability Technical Committee promotes air and spacecraft crash for purposes of a simulation that will be im- survivability as a design discipline that includes such factors as proved through a validation process. The aircraft crashworthiness, combat and repairability. contained 24 ATDs, fi ve of which were advanced experimental. The fuselage and dummies contained he U.S. Air Force this year continued studying NASA researchers a total of 500 sensors to capture accelerations and the effects of high-energy lasers on composite swung this Fokker F-28 loads. The test was conducted in cooperation with aircraft skins and testing mitigation technolo- MK1000 jet into terrain in the FAA. Additional partners included the U.S. Army, June to measure the gies against thermal damage. These tests un- e ects on crash test the National Highway Traffi c Safety Administration der the High Energy Laser program centered dummies and the and the National Transportation Safety Board. Ton back surface fi re, penetration vulnerability and structure. In the military space arena, the U.S. Defense the screening of potential hardening technologies. NASA Department in March created the Space Devel- Results of this Joint Aircraft Survivability Program opment Agency to accelerate the development Offi ce effort will establish a baseline thermal radiant of next-generation small satellite architectures. fi eld. Various hardening technologies supplied by These proliferated constellations would be harder the Air Force Research Laboratory, Naval Research to attack than the small number of large satellites Laboratory and Air Force Institute of Technology that today provide critical services mainly through were applied to structures to determine their ability the Air Force. to mitigate or delay laser damage. NASA’s vision for landing humans on Mars by The Air Force conducted tests on fi ve fuel tanks the late 2030s hinges on achieving survivability to of various sizes to gather data about their vulnera- two to three years of continuous weightlessness bility to fuel vapor explosion due to threat-induced and bombardment by cosmic ionizing rays on the tank ullage ignitions. Five tanks of 950- to 5,300- crew and their capsule. Until effective protective liter capacity were studied, with testing on the fi fth solutions such as astronaut suits and protective tank completed in October. Ullage conditions and capsule can be developed, astronauts will make use fuel temperatures were varied to determine ullage of the planned lunar Gateway as a staging station overpressure ratio curves for each of the tanks. Tests for the eventual human mission to Mars. In May, were conducted under pressure conditions ranging NASA awarded a contract to Maxar Technologies of from ambient to under 28 kilopascal. Five hundred Colorado for the Gateway’s Power and Propulsion tests were completed, and about 650 expected by the Element and in July to Northrop Grumman for the end of the program. The data will aid the defense habitation module. In preparation, NASA plans to industry in fuel tank design and structural integrity launch an uncrewed Orion module on a heavy-lift studies and will be used in the Next Generation Fire Space Launch System rocket in late 2020, followed Prediction Model. by the fi rst launch with a crew in 2022. ★ In June, NASA’s Langley Research Center conducted a swing test into terrain with a Fokker F-28 MK- Contributor: Martin S. Annett

aerospaceamerica.aiaa.org | DECEMBER 2019 | 17 AEROSPACE DESIGN AND STRUCTURES

Progress made on U.S. acquisition policy According to Mike Sievers, USC lecturer and senior systems engineer at NASA’s Jet Propulsion Lab and technical fronts in California, “The USC lab’s work aims to develop an open architecture and tool set that facilitates BY JEFFREY NEWCAMP plug-and-play experimentation for cyber-physical systems.” An open architecture for digital twins The Systems Engineering Technical Committee supports efforts to defi ne, develop and disseminate modern systems engineering practices. can expand the market for the technology because creating digital twin platforms is expensive and ystems engineering leapt ahead in 2019 time-consuming. Sievers and his colleagues be- with the enactment of a United States Code lieve that digital twin progress this year has been change, large advances in modular open instrumental for industry, government and uni- systems architecture research capabilities versity developers. Open architecture could lead for digital twin technology and a new U.S. to a watershed moment for system development, SAir Force strategy. as other technologies have recently experienced. In January, Azad Madni, Carla Madni and Scott Building open architecture systems is analogous Lucero published a comprehensive call to action to opening the fl oodgate. for applying model-based systems engineering, or Starting Jan. 1, 10 U.S. Code section 2446a began MBSE, to digital twin technology. MBSE gives sys- requiring any defense acquisition programs reaching tems engineers another tool with which to develop Milestone A or Milestone B to design and implement solutions for complex problems in the digital twin a modular open systems, or MOSA, approach. The realm. The authors project that digital twins will Defense Department desires highly cohesive, loosely continue to transcend the obvious applications for coupled and severable modules in new weapon sys- aircraft and complex machines and grow in fi elds tems that will increase both fl exibility and acquisition like construction and real estate. This landmark competition. A team of researchers at the Air Force publication inspired systems thinkers and refl ected Research Laboratory’s Munitions Directorate at the momentum that the topic gained this year. Eglin Air Force Base, Florida, spent 2019 expanding In May, researchers led by Madni at the Univer- its take on a MOSA. They built the Munitions Open sity of Southern California founded the Distributed Architecture Test and Evaluation Lab, or MOATEL, Autonomy and Intelligent Systems Laboratory. where they can test interchangeability of components According to Madni, executive director for the USC for kinetic weapons. systems architecting and engineering program, “In MOATEL allows engineers to test adherence to July, we demonstrated rudimentary digital twin 10 U.S. Code section 2446a and specifi cally targets technology for multiquadcopter search missions. module interfaces. For example, MOATEL engineers [Then] in September, we demonstrated rudimentary can test whether a newly acquired missile’s seeker Aircraft manufacturers digital twin technology for autonomous cars.” This can be replaced by a higher tech seeker without nega- can perfect a design before prototyping with groundbreaking research showed the capability to tively impacting system performance. This capability digital twins. collect data from the autonomous cars to populate may increase system lethality for the Department of Siemens illustration the digital twin. Defense and decrease system lifecycle cost. In April, then-Air Force Sec- retary Heather Wilson released a science and technology strategy for the service. It focuses on systems-of-systems innovation, how the service manages technological projects and provides a call to action for the future. Systems engineering is a principal actor to use for solving technical Air Force problems and will be used extensively during this strategy’s implementation. As 2020 overtakes 2019, the systems engineering discipline will become larger, more relevant and more capable because of the policy and progress achieved in the past year. ★

18 | DECEMBER 2019 | aerospaceamerica.aiaa.org AEROSPACE SCIENCES

Increasing power, speed and mobility were also briefed at AIAA’s Aviation Forum in June. Data from the Galveston flights is helping guide without the negative impacts of noise researchers in preparation for community response fl ights by NASA’s X-59 low boom demonstration aircraft. BY NATHAN E. MURRAY In July and August, NASA F/A-18 test aircraft fl ew The Aeroacoustics Technical Committee addresses the noise produced by over the Mojave Desert where researchers from Volpe the motion of fl uids and bodies in the atmosphere and the responses of and Brigham Young University tested a 30-mile-long humans and structures to this noise. microphone array in preparation for acoustic testing and validation of the X-59. eeking to understand the interactional noise Turning to conventional jets, analyses of mea- mechanisms associated with unmanned air sured fl yover noise data from a full-scale Boeing systems and urban air mobility vehicles, re- 737-7 with a NASA-designed advanced inlet acoustic searchers at NASA’s Langley Research Center in treatment demonstrated a 3.2 decibel cumulative Virginia conducted experiments in September reduction in inlet noise. Research progressed this Sin the Low Speed Aeroacoustic Wind Tunnel. The re- year toward meeting NASA’s Advanced Air Transport search team measured the aerodynamic and acoustic Technology goal of 4 db or 37% airframe noise re- performance of multiple propellers interacting with duction for a high-lift tube and wing confi guration. a traversable, meaning moveable, wing geometry. This progress was enabled by a December 2018 test In March, the U.S. Transportation Department’s in the 14-by-22-foot Subsonic Tunnel at Langley in Volpe Center in Massachusetts, in conjunction with which a novel in-wall microphone array isolated the Helicopter Association International HeliExpo slat noise from other noise sources. This array was 2019 and the Fly Neighborly Committee, released an recessed behind an acoustically transparent screen online pilot and operator training program through to perform measurements on a 10%-scale high-lift Co-rotating propellers aircraft model. are tested in proximity to Sponsored by the U.S. Offi ce of Naval Research, a traversable wing researchers from Lockheed Martin, Spiritech and geometry in the Low Penn State completed an investigation of the noise Speed Aeroacoustic Wind Tunnel at reduction potential of Spiritech’s STAR, for Multi- NA SA’s Langley Research Stream Coupled Throat Variable Rotating, nozzle Center to assess acoustic concept. The May results showed signifi cant noise directivity and amplitude reductions for static takeoff engine power settings sensitivity to parameters when compared with contemporary tactical aircraft including relative phasing of the propellers as well jet exhaust nozzles. as spatial location of the website of the FAA WINGS pilot profi ciency pro- Also this year, signifi cant facility advancements the wing relative to the gram. Aircraft noise data and modeling developed in were made. Specifi cally, improved microphone ar- propeller disks. partnership with NASA, FAA and the U.S. Army was ray measurements were realized in May when ATA NASA inserted directly into the WINGS training program to Engineering and the University of California, Irvine, help pilots fl y quieter. performed jet noise measurements using a collection With funding from Uber Elevate, the Advanced of both stationary and continuously moving micro- Acoustic Model simulation tool, a computer program phones. The technique approached the theoretical that calculates community noise from aircraft fl ight limits of a continuous series of sensors using only a operations, was updated in May by Volpe to support modest number of microphones. research in the assessment of community noise and Advancements in aeroacoustic wind tunnel testing audibility of electric vertical takeoff and landing aircraft. were realized in June when NASA’s Glenn Research In June and July, NASA and FAA conducted he- Center in Cleveland completed a renovation of the licopter noise abatement tests at Coyle Field, New 9-by-15-foot Low Speed Wind Tunnel using a novel Jersey, with a Sikorsky S-76D, a U.S. Coast Guard “aerodynamically smooth but acoustically transpar- HH-65 Dolphin (a variant of the commercial Airbus ent” surface developed in collaboration with Jacobs AS365 Dauphin), a Leonardo AW139 and a Bell 205 Engineering and Virginia Tech. The new lining makes with the goal of improving community acceptance the walls of the tunnel seem acoustically invisible and of helicopter operations. virtually eliminates the problem of separating the In the area of supersonic fl ight, researchers briefed noise of the wind tunnel itself from the noise of the the International Civil Aviation Organization’s Work- fl ow over the test article mounted inside the tunnel.★ ing Group 1, which is concerned with aircraft noise, in April about the results of the November 2018 sonic Contributors: Christopher Bahr, Cliff Brown, David thump community response testing in Galveston, Lockard, Doug Nark, Eric Nesbitt, Juliet Page, Tony Pilon, Texas. The results of the fl ights by NASA F/A-18 jets Parthiv Shah, Jonathan Rathsam and Nik Zawodny

aerospaceamerica.aiaa.org | DECEMBER 2019 | 19 AEROSPACE SCIENCES

Enabling diagnostics for opaque fl ows, and temperature-sensitive paint, or cntTSP, can measure boundary-layer transition on complex 3D complex surfaces and nonintrusive fl ow wind tunnel models, since the carbon nanotube layers create homogeneously distributed surface measurements heating. The cntTSP sensor can visualize the surface boundary-layer temperature distribution that BY THOMAS P. JENKINS AND DAVID H. PLEMMONS arises due to the different heat transfer coeffi cients The Aerodynamic Measurement Technology Technical Committee advances for laminar and turbulent fl ow. A wide area of in- measurement technology for ground facilities and aircraft in fl ight. terest for the use of cntTSP is the integration of the different cntTSP layers into complex 3D geome- n January, Huixuan Wu’s group at the University tries like nacelles, which the aircraft industry needs of Kansas demonstrated a novel magnetic par- to improve the data quality of wind tunnel tests. In ticle tracking technology, or MPT. Unlike other the research, DLR investigated the applicability of Iadvanced fl ow diagnostic methods, MPT tracks cntTSP to a generic nacelle at the cryogenic test fa- an object with a magnetic fi eld. It does not rely on cility Pilot European Transonic Wind Tunnel. The optics and can be used in a completely opaque en- team achieved fl ow visualization of the laminar to vironment. Meanwhile, it does not involve radioac- turbulent boundary-layer transition appearing on tive materials or X-rays, so the operation is safe and the nacelle. easy. Although this idea dates back to at least the In July, as part of a U.S. Air Force-sponsored 1990s, previous researchers relied on optimization project, MetroLaser Inc. demonstrated a diagnos- algorithms to reconstruct the particle trajectory. tic method for spatially resolved simultaneous However, optimization is time-consuming, which measurements of density and velocity that can limits its application. Wu’s group replaced the op- be applied to supersonic fl ows and that does not timization-based approach with the use of a non- require fl ow seeding. The method, named two- linear Kalman fi lter, which increased the speed of cell fi ltered Rayleigh scattering, involves illumi- Two-dimensional reconstruction by three orders of magnitude and nating the measurement region with a laser sheet ima ges of the increased the accuracy and resolution. In May, the and measuring Rayleigh-scattered light from the freestream-normalized University of Kansas team applied the MPT tech- fl ow with two cameras, each fi ltered by an iodine density (a) and the velocity (b) of a supersonic nique to investigate a sheared dense granular fl ow vapor cell of a different pressure. The methodolo- cofl ow jet consisting of a in a Couette cell. They observed many interesting gy is based on a mathematical model that relates fast-moving core fl ow and phenomena, such as the tendency of horizontal the Rayleigh-scattered light collected through the a surrounding slower con- alignment of rods in the fl ow. fi lter to the pressure, temperature and velocity of centric fl ow. The cofl ow jet In April, DLR, the German Aerospace Center, the fl ow. The model was used to convert the mea- is used for demonstrating these nonintrusive fl ow applied temperature-sensitive paint to engine sured light intensities to density and velocity for diagnostics. nacelles to investigate laminar-to-turbulent tran- each point in a 2D image of the fl ow. MetroLaser MetroLaser Inc. sition. The combination of carbon nanotubes demonstrated the technique on a supersonic cofl ow jet and correctly captured the 2D density fi eld both spatially and quantitatively. The team also demonstrated feasibility of measuring the 2D velocity fi eld, but limitations in the simplifi ed image registration method used for this feasibility study resulted in some errors in the spatial velocity distribution. The use of more rigorous image registration methods, along with suggested improvements in the selection of iodine cell pressures, should enable the method to achieve an es- timated 4% accuracy in both density and velocity in an optimized system. ★

Contributors: Christian Klein and Huixuan Wu

20 | DECEMBER 2019 | aerospaceamerica.aiaa.org AEROSPACE SCIENCES

Testing designs to increase aircraft Whether a helicopter station keeps above a highway to report the traffi c or stays in close prox- fuel effi ciency imity to the side of a mountain to deliver supplies to a remote community, hover is an elegant and BY NATHAN HARIHARAN complicated fl ight condition. Numerical simulation The Applied Aerodynamics Technical Committee emphasizes the of hover is full of challenges but offers the reward development, application and evaluation of concepts and methods using of great understanding of performance and loads. theories, wind tunnel experiments and fl ight tests. Better understanding will lead to more effi cient, capable and safer rotor designs. The upcoming NASA-sponsored tests at the National Full-Scale Aerodynamics Complex at NASA’s Ames Research Center in California will offer an even richer data set for code and process benchmarking. These tests are scheduled for mid- to late 2020. In August, NASA and Boeing, as part of the High Aspect Ratio Wing Subproject within the NASA Advanced Air Transport Technology Project, completed tests on the 4.5%-scale, Mach 0.80 Transonic Truss-Braced Wing, or TTBW, model in the Ames 11-Foot Transonic Wind Tunnel. The objectives were to acquire a test database to validate the aerodynamic performance and vehicle stability and control characteristics. Force and moment, surface pressure, model deformation, oil fl ow visualization and drag rise data were collected to support the assessment of stability and control characteristics. Data A NASA-Boeing 4.5% new NASA design method, referred to as were obtained at Reynolds numbers ranging from scale of a Transonic Crossfl ow Attenuated Natural Laminar 2 million to 8 million per foot and Mach numbers Truss-Braced Wing aircraft is tested in the Flow, was model-tested in June in the Na- ranging from 0.2 to 0.92. The TTBW concept shows 11-Foot Transonic Tunnel tional Transonic Facility, a high-pressure, promising fuel burn benefi ts toward meeting NASA at NA SA’s Ames cryogenic wind tunnel at NASA’s Langley system level metrics. Research Center. AResearch Center in Virginia. CATNLF carefully de- In May, a new active fl ow control innovation Boeing/NASA signs the leading-edge shape of the wing to enable was tested under NASA’s Advanced Air Transport natural laminar fl ow on typical transport wings with Technology project, using a 10%-scale high-lift high sweep and Reynolds numbers. Laminar fl ow version of the Common Research Model with has been studied for decades because of its promise simple-hinged fl aps at Langley’s 14- by 22-Foot for reducing fuel burn via decreased aircraft drag. Subsonic Wind Tunnel. The objective of the test Laminar flow on typical transport wings would was to investigate a novel high-lift method that provide the largest performance benefi t, but previ- eliminates Fowler-fl ap mechanism and external ous laminar fl ow strategies required the vehicle to fairing on a conventional high-lift confi guration. either fl y slower or add a complex suction system, High-lift confi gurations are needed only during and both penalties made the technology too costly takeoff and landing phases of any fl ight and are to buy its way onto the aircraft. typically retracted during cruise phase of the Transition visualization techniques used in the fl ight. Eliminating external fairings associated with June wind tunnel test showed a near doubling of the conventional Fowler-fl aps reduces the drag during extent of laminar fl ow over the extents previously the cruise phase of the fl ight and saves fuel. The seen in any natural laminar fl ow experiment on active fl ow control innovation, High Effi ciency wings with comparable sweep. Encouraging wind Low Power actuators, achieved a targeted lift co- tunnel results have spawned a series of fl ight tests effi cient increase of 0.50 using a moderate amount to further advance the CATNLF technology in fl ight of mass fl ow and air pressure. The simple-hinged environment. fl ap confi guration equipped with this actuation In January, rotorcraft researchers reported making technology was able to match or exceed the lift signifi cant strides in determining the importance performance of the reference conventional high- of fl ow transition and understanding mechanisms lift confi guration. ★ of vortex-wake breakdown. The findings were published at AIAA’s Hover Prediction Workshop in Contributors: John Lin, Michelle Lind, San Diego. Latunia Melton and Robert Narducci

aerospaceamerica.aiaa.org | DECEMBER 2019 | 21 AEROSPACE SCIENCES

In June, the U.S. Air Force Research Laboratory launched its Demonstration and Science Experiments, or DSX, mission to study the radiation environment of near-Earth space. By July, the mission had unfurled its long antenna booms, including one pair measuring 80 m (262 feet) tip-to-tip, to become the largest uncrewed three-axis stabilized spacecraft ever fl own. In February, OneWeb moved closer to its goal of providing global internet services with the launch of its fi rst six satellites. The satellites were raised to their fi nal 1,200 km orbit and demonstrated data rates up to 400 megabytes per second. These satellites represent the fi rst of an initial constellation of 650 satellites that will ultimately grow to a total of 1,980 satellites. SpaceX reached a similar milestone in May when it A year of exploration and launched the fi rst 60 satellites of the Starlink constellation into orbit. Starlink seeks to also provide commercialization of space global broadband services with an approved con- BY BRIAN C. GUNTER stellation of nearly 12,000 satellites in orbits ranging in altitude from 340 km to 1,150 km. In July, The Astrodynamics Technical Committee advances the science of trajectory Amazon’s Kuiper Systems proposed an additional determination, prediction and adjustment, and also spacecraft navigation and attitude determination. broadband constellation of 3,236 satellites, with all satellites targeting an altitude below 630 km. If all A stack of 60 Star- he astrodynamics community was active three “megaconstellations” reach full implemen- link satellites ready in a number of exploratory and commer- tation, this would represent 17,000 new orbiting for launch. SpaceX cialization efforts this year, starting with satellites, signifi cantly increasing the number of has approval to launch NASA’s New Horizons spacecraft’s January objects in low Earth orbit and highlighting policy about 12,000 global T broadband satellites. fl yby of Ultima Thule. Following the fl yby of Plu- concerns regarding regulation of space activity and Starlink to by New Horizons in 2015, the encounter with orbital debris. Ultima Thule, a binary Kuiper Belt object orbit- The private utilization of space took anoth- ing approximately 6.6 billion kilometers from the er step forward when the Beresheet mission sun, represents the most distant planetary body launched in February and attempted to land on ever reached by a spacecraft and returned valu- the lunar surface. Israeli-based nonprofi t SpaceIL able imagery and other data regarding these re- developed the mission, and although the lander mote and ancient objects. ultimately crashed during the fi nal descent phase, Exploration of the solar system continued with it represented the fi rst attempt by a private enti- other notable achievements from ongoing deep- ty to land a payload on the moon. Another lunar space missions, such as the close approaches to milestone was achieved a few weeks earlier when the sun by NASA’s Parker Solar Probe (the third China’s Chang’e-4 was the fi rst to place a lander of which was in September) and multiple touch- and rover on the far side of the moon in January. A downs and sample-collection maneuvers by the separate effort by the Indian Space Research Orga- Japan Aerospace Exploration Agency’s Hyabusa2 nization to place the Vikram lander on the lunar mission at the Ryugu asteroid. surface was attempted in July, nearly coinciding While not a deep-space mission, the crowd- with the 50th anniversary of the Apollo lunar land- funded LightSail 2 mission developed by the ing. Communications were lost with the lander California-based Planetary Society deployed its during the descent; however, the primary lunar or- 32-square-meter solar sail in July and later verifi ed biter, Chandarayaan-2, was fully operational as of that the satellite was able to raise its apogee by the November and was to proceed with its seven-year solar radiation pressure on the sail. By demon- mission to study the composition of the lunar sur- strating “fl ight by light” for cubesats, the mission face. These international attempts to return to the has paved the way for future small satellites to ex- moon, complemented by NASA’s Artemis lunar explore the solar system without the use of tradition- ploration program, show the global renewed inter- al propulsion systems. est in lunar research and exploration. ★

22 | DECEMBER 2019 | aerospaceamerica.aiaa.org AEROSPACE SCIENCES

The XQ-58A Valkyrie demonstrator completed its inaugural ﬂ ight in March at Yuma Proving Ground, Arizona. U.S. Air Force

Paving the way for autonomous weapons, vehicle fabrication was underway with the plan of the fi rst test fl ight from Cecil Spaceport in Jackson- hypersonics, human spacefl ight ville, Florida, in early 2020. The SpaceX Crew Dragon Demo-1 launched BY CHRISTOPHER D. KARLGAARD on a SpaceX Falcon 9 from Kennedy Space Center The Atmospheric Flight Mechanics Technical Committee addresses the on Feb. 28 before docking with the International aerodynamic performance, trajectories and attitude dynamics of aircraft, Space Station on March 3. The uncrewed orbital spacecraft, boosters and entry vehicles. fl ight test carried cargo and a simulated passenger. It then undocked on March 8, reentered the n March, the U.S. Air Force’s XQ-58A Valkyrie atmosphere and splashed down in the Atlantic unmanned combat aerial vehicle took off from Ocean. The success of this test was a milestone in Yuma Proving Ground in Arizona on its fi rst the SpaceX Crew Dragon program, paving the way Ifl ight. San Diego-based Kratos Defense and Se- for a fl ight test with crew for the Demo-2 mission. curity Solutions designed and built the XQ-58A In April, the Crew Dragon capsule that fl ew for the under contract with the Air Force Research Lab- Demo-1 fl ight test was destroyed during a ground oratory as a low-cost strike aircraft demonstration test of the SuperDraco engines, the abort engines vehicle. The contract was awarded in July 2016. that would carry the Crew Dragon away from a The Valkyrie design incorporates stealth technol- failing Falcon during launch. ogy that can carry weapons or surveillance pay- NASA’s Orion program tested its Launch Abort loads. Four more fl ight tests are planned in order System, or LAS, in July. The Ascent Abort-2 fl ight to further evaluate the vehicle’s performance. test was launched on a modifi ed Peacekeeper AFRL’s X-60A hypersonic research vehicle profi rst-stage missile from Kennedy Space Center gram completed its critical design review early in in Florida. The booster carried the capsule and 2019. The X-60A is an air-dropped, single-stage, LAS to an altitude of approximately 30,000 feet at suborbital vehicle powered by a liquid-fueled rock- Mach 1.15. The LAS then initiated the abort fl ight et motor. It was designed as a research platform test, pulling the Orion capsule test article away for conducting fl ight tests of hypersonics technol- from the booster and reorienting the vehicle for ogy in the range of Mach 5-8 at altitudes between splashdown into the Atlantic Ocean. Data ac- 70,000 to 130,000 feet (20-40 kilometers). The X-60A quired during the July test will be used to validate is designed to be dropped from a NASA C-20A air- prefl ight models and to prepare for the Artemis-1 craft. AFRL is conducting the project in partnership mission in which a Space Launch System rocket with Atlanta-based Generation Orbit Launch Ser- will boost an uncrewed Orion capsule around the vices Inc. With the critical design review complete, moon. ★

aerospaceamerica.aiaa.org | DECEMBER 2019 | 23 AEROSPACE SCIENCES

visualizations and pressure measurements at Experimental-numerical campaigns give Mach 2. Results showed that a shock emanating from the wedge impinges on and wraps around the body insight into complex fl uid phenomena leading to crossfl ow separation and reattachment, BY DAVID GONZÁLEZ AND ALBERT MEDINA features that greatly differ from the well-documented 2D/3D canonical shock-wave boundary-layer in- The Fluid Dynamics Technical Committee focuses on the behaviors teractions confi gurations on fl at surfaces. of liquids and gases in motion, and how those behaviors can be Integrated approaches employing complemen- harnessed in aerospace systems. tary experimental and numerical campaigns such as that described above continue to provide fun- damental insight. These are critical to developing a deeper understanding of high-speed fl uid dynamic phenomena and enable the formulation of highly accurate modeling and advancement of simulation capabilities. Such complex-modeling profi ciencies will facilitate the development of materials suitable for the austere environments, the development of potential fl ow control techniques to mitigate heat transfer in key areas of interest and the effi cient design of next-generation high-speed fl ight vehicles. Regarding low-speed aerodynamics, researchers at AFRL pioneered the use of large-eddy simulation to study the fl ow processes leading to the on- First-ever measure- dvances in the fi eld of fl uid mechanics set of stall for a rapidly pitching airfoil. This effort, ments of hypersonic serve as testament to the breadth and rigor completed in March, highlighted the importance boundary-layer transition of the discipline, with contributions span- of understanding the unsteady boundary layer on a straight cone under ning all regimes from low-speed to hyper- development as the pitching airfoil approaches fully quiet fl ow conditions. A Heating to the wind tunnel sonics. In a fi rst, researchers at Purdue University the dynamic stall event. The researchers applied model surface starting observed a hypersonic boundary-layer transition large-eddy simulation over a range of Reynolds and at 108 cm is caused by on a 2.5-degree half-angle straight cone under fully Mach numbers as well as to fi nite wings, including the fl ow near the surface quiet fl ow conditions. These experiments in Feb- sweep effects and standard wind tunnel end-plate transitioning from smooth, ruary at the Boeing/Air Force Offi ce of Scientifi c laminar fl ow to chaotic, conditions. The technique resolved a highly com- turbulent fl ow. Research Mach-6 Quiet Tunnel documented the plex fl ow fi eld in which a transitioning, separated,

Purdue University growth, breakdown and transition to turbulence nonequilibrium boundary layer interacts with a of the second-mode instability. This mechanism locally supersonic fl ow. The research resulted in an dominates laminar-turbulent boundary layer tran- innovative fl ow control concept and insight into the sition in hypersonic fl ows and is characterized by unsteady interactions responsible for the dynamic a trapped acoustic wave. Researchers observed stall event. the primary manifestation of the increase of heat Between September 2018 and May 2019, re- transfer near transition onset and its continual sub- searchers at Los Alamos National Laboratory in sequent increase until the end of the cone. New Mexico developed physics-constrained ma- Shock-wave boundary-layer interactions are chine learning algorithms for spatio-temporal ubiquitous in high-speed fl ows, existing on internal modeling of turbulence, owing to a paucity of ma- and external surfaces of a supersonic/hypersonic chine learning algorithms capable of effectively fl ight vehicle. These interactions result in fl ow sep- modeling 3D datasets. Specifi cally, they developed aration, vortical structure formation, pressure loss- neural networks with a combination of convolu- es, induced pitching moments and other effects tional and recurrent architectures that account that are often detrimental to the vehicle’s opera- for spatial and temporal nonlinearities in fl uids. tion. Researchers at Florida A&M University, Flori- The resulting model can replicate high-fi delity 3D da State University and the U.S. Air Force Research turbulence at a computational cost several orders Laboratory collaborated in April and May in a study of magnitude lower than traditional numerical involving high-fi delity experiments and numeri- schemes. The performance of these learning algo- cal simulations for the Air Force Offi ce of Scientifi c rithms was quantifi ed on well-known cases in tur- Research to understand the fl ow physics associat- bulence with strong physics-based metrics. ★ ed with shock-wave boundary-layer interactions and shock-shock interactions on an axisymmet- Contributors: Stuart Benton, Brandon Chynoweth, ric confi guration. The researchers performed fl ow Rajan Kumar, Arvind Mohan and Steven Schneider

24 | DECEMBER 2019 | aerospaceamerica.aiaa.org AEROSPACE SCIENCES

Facility improvements make progress dynamics Complex at Moffett Field, California, while also executing several test programs in the amid heavy year of ground testing facility’s 40-by-80-foot Wind Tunnel in 2019. The complex suffered a Class A mishap in June 2017 BY PAT GOULDING II that destroyed all blades on one of its six fan mo- The Ground Testing Technical Committee focuses on evaluating aircraft, tors. The team continued efforts throughout 2019 launch vehicles, spacecraft, structures and engines in wind tunnels and to repair and retrofi t the 80-by-120-foot Wind other facilities. Tunnel — the largest wind tunnel in the world — with the intent of restoring the test capability he ground test community saw signifi cant by early 2020. Efforts are also ongoing to design, facility investments and improvements in procure and install a complete new set of fan 2019, building on efforts begun in previous blades on all six drive motors. This will restore Tyears, and produced an impressive array of the facility test capability to levels from before critical test data. the 2017 mishap and drastically extend the ser- NASA began fi nal verifi cation in September vice life of the drive system. on its largest investment in aeronautics research Facility improvement projects proceeded in- in several years — the acoustic improvements to ternationally as well. Throughout 2019, JAXA, the the 9-by-15-foot Wind Tunnel facility at NASA’s Japan Aerospace Exploration Agency, continued Glenn Research Center in Cleveland. Final com- to improve the performance of its new bird-strike missioning was expected to occur in December. It test apparatus at Chofu and to work toward for- will cap nearly two years of work to retrofi t exist- mal commissioning in 2020. The structure was ing portions of the wind tunnel circuit and replace installed in March 2018 and uses precisely cali- the fl ow liner material in the test section in order brated gelatin balls of specifi ed density to simu- to reduce background noise by up to 9.3 decibels. late bird strikes. It boasts a test speed range of 50 This dramatic improvement in noise attenuation to 400 meters per second (112-895 mph). JAXA will permit more accurate test and evaluation of also spearheaded efforts to advance wind tunnel newer and quieter turbofan propulsion systems, wall interference correction capabilities by ex- ensuring the facility remains viable and retains panding existing 3D wall panel method codes to The newly modifi ed test section in the 9-by- its status as a premier acoustics research asset for incorporate the unique boundary characteristics 15-foot Wind Tunnel at propulsion systems for decades to come. Custom- of Kevlar wall tunnels. Initial results showed excel- NASA’s Glenn Research er testing was scheduled to resume in December, lent agreement, and the method stands to provide Center has an improved following the fi nal commissioning. signifi cant insight to future test customers across acoustic liner to minimize Meanwhile, a team from the U.S. Air Force’s a broad array of facilities. tunnel background noise and improve acoustic Arnold Engineering Development Complex con- Back in the United States, NASA saw signifi - measurement quality. tinued to make progress toward restoring full cant test achievements, particularly in programs NASA test capabilities at the National Full-Scale Aero- at NASA’s Langley Research Center in Virginia and NASA’s Ames Research Center in California. Teams at Langley completed extensive testing related to NASA’s Space Launch System. This testing, completed in June, included deployment of a novel laser-based fl ow visualization technique in the Langley Unitary Plan Wind Tunnel as well as low-speed lift-off and transition testing in the 14-by-22-foot Wind Tun- nel. NASA also ran several tests at Langley, Glenn and Ames from March to September that involved iterations of NASA’s Common Research Model, studying high lift, laminar fl ow and acoustic characteristics. ★

Contributor: David Stark

aerospaceamerica.aiaa.org | DECEMBER 2019 | 25 AEROSPACE SCIENCES

AI advances military drone effectiveness, out: the use of a rotorcraft and autonomous navigation. Dragonfl y has an approximate 10-times lunar exploration advantage in power-to-weight ratio on Titan as compared to Earth. Dragonfl y will have inertial BY UDAY J. SHANKAR AND KEVIN P. BOLLINO and terrain-relative navigation with an inertial The Guidance, Navigation and Control Technical Committee advances measurement unit and optical sensors, enabling techniques, devices and systems for guiding and commanding fl ight vehicles. navigation and hazard detection in a feature-poor terrain with soft and diffused lighting. This matu- The Dragonfl y rotorcraft ntelligent automatic control relies heavily on ration of drones follows the development of min- will sample materials artifi cial intelligence and machine learning. iature sensors, autopilots and hazard-detection and determine surface The U.S. Department of Defense is making ma- methods. Dragonfl y will be launched in 2026 and composition in di erent jor progress in research and development in the arrive on Titan in 2034. geologic settings on I Saturn’s Titan moon. fi eld of autonomy amid a renewed emphasis on In the 50th anniversary year of Apollo 11, Johns Hopkins Applied Physics robotics and autonomous systems. three missions sought to land on the moon, with Laboratory In March, William Roper, assistant secretary a fourth planned for launch. In January, China’s of the U.S. Air Force for acquisition, technology Chang’e-4 became the fi rst spacecraft to land on and logistics, announced Skyborg, the Air Force’s the far side of the moon. The lander released a future AI-enabled fl eet for unmanned combat ae- rover, Yutu-2, which is exploring the basin of the rial vehicles. Skyborg will augment crewed fi ghter Van Karman crater. The Queqiao relay satellite jets with autonomous drones as their “wingmen.” — the fi rst satellite in a halo orbit at the Earth- This ongoing pursuit of fully autonomous aircraft moon L2 Lagrangian point — relays communi- that leverage AI and machine learning focuses not cations between ground stations and the space- only on the combat systems but also on the infra- craft. In contrast to the success of Chang’e-4, the structure and development environment such as Israeli Beresheet and the Indian Vikram landers networks and cloud servers to improve overall air- crashed during fi nal descent to the moon. In April, craft effectiveness. during Beresheet’s critical landing phase, it ap- In another AI-related initiative, the Air Force is pears its inertial measurement unit reset, shutting developing the Air Force Cognitive Engine soft- down the main engines. In September, the Vikram ware application, which was in beta testing in lander appeared to have a nominal descent until April, as its core infrastructure for AI development its fi ne breaking phase, when communication was to stimulate technological advancements in air- lost. The Indian Space Research Organization is craft, spacecraft and missiles. still looking for answers. Meanwhile, the co-man- For its next New Frontiers mission, NASA ifested Chandrayaan-2 orbiter, which reached its selected the Dragonfl y rotorcraft in June to ex- lunar orbit in August, is functioning well. Finally, plore the icy, unique and richly organic world in December, China was scheduled to launch the of Titan, Saturn’s moon. From a guidance, nav- Chang’e-5 lander and sample return — the fi rst igation and control perspective, two items stand since Luna-24 in 1976. ★

26 | DECEMBER 2019 | aerospaceamerica.aiaa.org AEROSPACE SCIENCES

Achieving advanced CFD capabilities Design in Virtual and Augmented Reality toolKit, or AArDVARK, an engineering-oriented virtual and with high-performance computers augmented-reality framework leveraging the CAPS infrastructure, demonstrated several relevant appli- BY JAMES MASTERS AND CAROLYN WOEBER cations, ranging from packaging to modal analysis. The Meshing, Visualization and Computational Environments Technical These demonstrations highlighted how the appro- Committee explores the application of computer science to pre- priate utilization of virtual reality can augment tra- processing, post-processing and infrastructure in support of ditional engineering analysis techniques. computational simulation in the aerospace community. Also on the computational environments front, the Computational Research and Engineering Acquisition Tools and Environments program released version 10.0 of Kestrel in May and version 10.1 in August. Support for axisymmetric 2D fl ow solutions was added to the primary fi nite volume fl ow solver in version 10.0 and to the high-order fi - nite element solver in version 10.1. This allowed for 3D bodies of revolution to be simulated in 2D while still reporting loads consistent with the full 3D confi guration. With the newest versions, it is also possible to restart a simulation with a different mesh system and visualization error from the Mach Hessian. High-order meshing algorithms continued to A CFD grid with 2.4 s problem size and complexity increases, make signifi cant progress. In June, researchers at million surface triangles the meshing community continues to grap- Mississippi State University demonstrated an ad- and 202 million volume ple with effective utilization of high-perfor- vancing-layer method for generating curved bound- cells was generated mance computing platforms, which was ary layer meshes. Pointwise entered its second year on a U.S. Navy F/A-18E A Super Hornet with the one of the impediments laid out in NASA’s Computa- of a NASA Phase II SBIR to develop a high-order mesh landing gear extended tional Fluid Dynamics Vision 2030 study. In January, capability that involves mixed-order degree eleva- using NASA’s TetrUSS representatives from Pointwise, Symmetric, Cascade tion and adaptation. High-order mesh generation up grid-generation soft- Technologies and Cambridge Flow Solutions made to degree three is also now available in Capstone, as ware. The image depicts strides toward this goal by demonstrating the ability well as the corresponding high-order visualization. iso-surfaces of vorticity colored by pressure and to generate and process meshes up to 13 billion el- MIT, Pointwise and Intelligent Light also continued clearly shows that the ements. Exascale computing on extremely large data to explore high-order visualization. Intelligent Light wake from the landing sets was further addressed in June when compression won a Phase II SBIR in June to pursue visualization gear and doors extends algorithms developed at Oak Ridge National Lab- for high-order simulations. far downstream. oratories in Tennessee demonstrated the ability to In January, Capstone released version 10, U.S. Navy compress time-accurate, unsteady, CFD data from which includes hexahedral elements in the 4.7 terabytes to 568 gigabytes. And Tecplot’s sub- boundary layer and tangential adaptivity for zone load-on-demand data structure allowed tran- boundary layers, allowing users to generate auto- sient solutions of 10 billion elements to be saved and matic smooth transitions with the unstructured stored on an engineering workstation. mesh. Version 10 also enhanced geometry capa- New Jersey-based Intelligent Light, funded by a bility with new repair techniques. U.S. Department of Energy Phase II Small Business Pointwise completed an SBIR Phase I contract Innovation Research grant, developed an uncertain- for the U.S. Air Force in March that focused on access ty quantifi cation proof-of-concept for large datasets to computational geometry from within the fl ow called Spectre-UQ, which demonstrated in January solver. MeshLink, an open source library released a technique to arrive at the total uncertainty for a in May as part of the contract, solves the problem of numerical study. geometry-mesh associativity while providing sim- Computational environments enabling rapid plifi ed access to the supporting geometry during multidisciplinary design are becoming increasing- mesh manipulation and adaptation. ly important. In response to this trend, the Com- Finally, researchers from the French National putational Aircraft Prototype Syntheses research Research Institute made a signifi cant advance- program, of which the Massachusetts Institute of ment in turbomachinery applications when Technology and Syracuse University are primary they demonstrated the viability and effi ciency of developers, provided infrastructure to enable mul- unstructured anisotropic mesh adaptation tech- tifi delity, multidisciplinary, physics-based air- niques to turbomachinery applications including craft design. In June, the Aerospace Analysis and internal regions with periodic boundaries. ★

aerospaceamerica.aiaa.org | DECEMBER 2019 | 27 AEROSPACE SCIENCES

August design review. A four-passenger cockpit Training pilots to handle the worst with with a wrap-around visual system was mated to the center’s vertical motion simulator. The Vertical realistic simulators Motion Simulator’s large amplitude motion system BY DANIEL KEATING enables researchers to explore ride quality in a safe and cost-effective manner. The Modeling and Simulation Technical Committee focuses on simulation of Also, eye-tracking technologies are rapidly atmospheric and spacefl ight conditions to train crews and support design and development of aerospace systems. advancing and fi nding applications in fl ight simulation and training. Several companies are providing n March, all pilots from scheduled air carriers in eye-tracking systems to measure pilots’ focus in the United States began using fl ight simulators response to various stimuli. A study was conducted to meet federally mandated upset prevention and in August with a level-D full fl ight simulator — the recovery training requirements. The FAA ordered highest standard, which includes motion feedback the simulator training before the two Boeing 737 — at a U.S.-based airline. Eye tracking was used to IMAX crashes that have been attributed to loss of determine the effects of having the fl ight director control. Meeting these requirements should improve (the roll and pitch attitude guidance on the primary the airline safety record, as the rare occurrences of fl ight display) on or off on pilots’ ability to monitor loss-of-control in fl ight still represent the leading the fl ight path effectively. This study was part of cause of fatalities in the worldwide commercial a joint FAA/Ames project toward improving pilot jet fl eet. From 2016 to 2019, the FAA approved 400 training for fl ight path monitoring. Further research simulators for training after improvements in the is required to identify the usefulness of eye tracking machines’ aerodynamic modeling. To date, the in training. overwhelming feedback from airline pilots who Virtual reality technologies from the gaming have taken the training has been positive. industry are beginning to make their way into various Turning to urban air mobility, which NASA aspects of fl ight simulation, and training applications defi nes as a safe and effi cient system for air pas- in particular. Airline applications include cabin crew senger and cargo transportation within an urban training, maintenance training and special-purpose area, passenger acceptance is one of the many pilot training, such as head-up display familiarization challenges to it becoming a reality. To help ad- where the optics are focused at infi nity. At NASA, the View from inside the dress this challenge, NASA’s Ames Research Center use of VR for astronaut training will increase with cockpit of the Ride Quali- ties Cab simulator cabin. in California this year prepared a new simulator new training requirements being introduced for NASA cabin called Ride Qualities Cab to run with the long-duration space missions. In addition, the Air center’s Vertical Motion Simulator, following an Force is looking to increase the use of VR to bridge the training-to-experience gap. An experiment was performed at Ames in September to investigate how performing a roll control task in VR compares to performing the task in a simulator with conventional visu- als, and if pilots’ utilization of peripheral visual cues is different. Another experiment focused on determining the visual-motion thresholds for VR sickness, which is still the biggest factor preventing the technology from reaching its full potential for training. ★

Contributors: Steven Beard, Jeffery Schroeder and Peter Zaal

28 | DECEMBER 2019 | aerospaceamerica.aiaa.org AEROSPACE SCIENCES

Promising technologies from plasmas, of the diagnostic method Electric Field-Induced Second Harmonic Generation, which applies a lasers, directed energy femtosecond laser beam to enable time-evolved electric fi eld measurements in partially ionized BY SALLY BANE AND JOSEPH W. ZIMMERMAN plasmas. This technique is extremely valuable as The Plasmadynamics and Lasers Technical Committee works to apply the the electric fi eld is a critically important parameter physical properties and dynamic behavior of plasmas to aeronautics, for tailoring plasmas for a wide range of applica- astronautics and energy. tions, from plasma fl ow and combustion control to plasma medicine. The researchers achieved measurements of electric fi elds with subnanosec- ond time resolution and spatial resolution down to tens of microns, allowing clear measurements of an ionization wave propagating with a velocity of 0.3 millimeters per nanosecond. In June, plasma-assisted combustion researchers from the Aerospace Department at Texas A&M University presented on simulations predicting a decrease of the defl agration-to-detonation transition time in ducts obtained using localized plasma perturbations. The plasmas were modeled as sources of radicals introduced in front of a defl agration fl ame propagating in a stoichiometric hydrogen/ air mixture with turbulent fl ow. These preliminary results demonstrate the potential of plasmas for de- creasing defl agration-to-detonation transition time and increasing turbulent burning velocity. Researchers at Xi’an Jiaotong University in Chi- na reported on efforts with new plasma approaches for both plasma-assisted combustion and plasma fl ow control. In February, they presented a new plasma-assisted combustion approach that uses The Tactical his year was prolifi c for advanced studies the heating and reforming effects of gliding arc High-Power Opera- and demonstrations of plasma and directed discharges in a swirl-stabilized burner to extend tional Responder was energy technologies in aerospace. the lean ignition and extinction limits. In August, developed to defend air bases against swarms of T In a leading development, the U.S. Air this same group presented research that applied a drones. Force Research Laboratory demonstrated the “stream-wise plasma heat knife” installed on the Air Force Research Laboratory Tactical High-Power Operational Responder, or leading edge of an airfoil model to perform anti- THOR, anti-drone technology in June. THOR ap- icing and de-icing. The novel technology applies an plies a high-powered microwave beam to disrupt array of streamwise-oriented nanosecond-pulsed drone electronics, causing the drone to crash. dielectric barrier discharges to provide rapid- Researchers envision this transportable system response local heating to the airfoil leading edge. as a means to counter major military threats, in- Notre Dame researchers working with Inno- cluding disabling swarms of drones within its vation Technology Applications Co. continued beam path simultaneously. to report encouraging results from drag-reduc- In January, Emory University researchers re- tion experiments using arrays of pulsed-direct- ported advancements in optically pumped rare current dielectric barrier discharge plasma actu- gas metastable lasers, in which they doubled ators. The plasma actuators produced a spanwise the optical pumps applied to a resonator volume velocity component in the boundary layer, result- containing an argon gas discharge to achieve ing in as high as 76% viscous drag reduction over an output power of 7 watts. Scaling of a similar a surface in the Mach number range of 0.05 to xenon-based laser was also demonstrated with 1 0.5. The most recent experiments, reported on in W output. This new laser technology, which op- September, demonstrated this technology em- erates at near infrared wavelengths, is a potential bedded in a NACA 63-012A airfoil model with free logistically simplifi ed alternative to the classic stream Mach numbers in the range of 0.3 to 0.5, high-power diode-pumped alkali lasers. providing 45% reduction in viscous drag as a well In July, researchers at Princeton University pub- as a net power savings that increased with Mach lished about new work that pushed the boundaries number. ★

aerospaceamerica.aiaa.org | DECEMBER 2019 | 29 AEROSPACE SCIENCES

Dragonﬂ y will have eight rotors to ﬂ y to locations on Titan to search for prebiotic chemicals. Johns Hopkins Applied Physics Laboratory

radiative heat fl ux. Advances in thermal management for Multiple advancements were made this year in the area of high-speed fl ight. In January, DARPA be- hypersonic fl ight and Titan exploration gan an initiative called the Materials Architectures BY AARON BRANDIS, JONATHAN BURT and Characterization for Hypersonics, or MACH, AND CHARLES BERSBACH program. MACH seeks to develop new materials The Thermophysics Technical Committee promotes the study and and designs for cooling the hot leading edges of application of mechanisms involved in thermal energy transfer and hypersonic vehicles fl ying more than fi ve times the storage in gases, liquids and solids. speed of sound, Mach 5. The fi rst goal is to develop fully integrated leading-edge solutions for use in ragonfl y, a mission to send a robotic octo- near-term hypersonic vehicles. In May, researchers copter lander to Saturn’s largest moon, was at Sandia National Laboratories fi nished high-speed selected in June for NASA’s New Frontiers experiments that for the first time characterized 4 program. The Johns Hopkins Applied the vibrational effect of the pressure fi eld beneath Physics Laboratory leads the Dragonfly a turbulent hypersonic region. The pressure fi eld is Dmission, whose goal is to study prebiotic chemistry key to understanding how intermittent turbulent and habitability of the ocean world that is Titan. Due spots affect vehicles fl ying at Mach 5 or higher, and to the dense, calm atmosphere and low gravity on these advancements in understanding may lead to Titan, an octocopter is an ideal vehicle to explore a better vehicle design. variety of locations. Thick insulation and heat from In March, Reaction Engines Limited, or REL, the Multi-Mission Radioisotope Thermoelectric completed the first phase of high-temperature Generator, or MMRTG, maintain the lander interior ground testing for its pre-cooler heat exchanger. To at relatively benign temperatures, typical for space rapidly cool air entering a gas turbine engine under components throughout the mission. The MMRTG is supersonic or hypersonic flight conditions, the particularly effective on Titan as it emits heat along pre-cooler pumps gaseous helium through several with charging the batteries that provide the power thousand microtubes. Tests were conducted at an required for fl ight. Dragonfl y requires sustained REL test facility in Colorado, where the pre-cooler heat for thermal management because it can’t rely was subjected to the exhaust stream from a General on solar power on Titan. The moon’s distance from Electric J79 turbojet engine. The pre-cooler was the sun and hazy atmosphere combine for a surface able to quench 420-degree Celsius intake air to temperature of minus 179 degrees Celsius. around 100 degrees in less than 0.05 second, for a Working with scientists led by NASA’s Ames heat transfer rate of approximately 1.5 megawatts Research Center in California, Dragonfl y’s team is at infl ow conditions corresponding to a freestream also proposing an instrumentation suite to obtain Mach number of 3.3. The pre-cooler is intended as aerothermal data relevant to thermal protection a component of the REL Sabre hybrid air-breathing system, or TPS, design during the atmospheric rocket engine and for other hypersonic fl ight appli- entry phase. The entry instrumentation package cations including vehicle thermal management and aims to measure near-surface and in-depth TPS extending the operable Mach number range of gas temperatures, surface pressure, total heat fl ux and turbine engines. ★

30 | DECEMBER 2019 | aerospaceamerica.aiaa.org AIRCRAFT TECHNOLOGY, INTEGRATION AND OPERATIONS

Developing parachute systems for space and military BY OLEG YAKIMENKO The Aerodynamic Decelerator Systems Technical Committee focuses on development and application of aerodynamic decelerator systems and lifting parachutes, pararotators, and inﬂ atables for deceleration, sustentation and landing of manned and unmanned vehicles.

arachutes for the SpaceX Crew Dragon and the Boeing CST-100 Starliner spacecraft were tested throughout 2019, aimed at com- Ppletion of qualifi cation and reliability tests to fl y humans in early 2020. Both companies have said they plan on starting human fl ight in 2020. NASA declared the results of November’s Star- liner’s pad abort test to be acceptable, even though A 19,000-kilogram test ponents of the Heavy Equipment Large Low Veloc- one of the capsule’s three main parachutes did not of a cluster of eight G-16 ity Airdrop System for 27,000- to 36,000-kilogram deploy due to a loose pin. parachutes. payloads. It also ground-tested the ATAX modular U.S. Army The parachutes that will ensure NASA’s Ori- airdrop platform — which uses airbags — culmi- on spacecraft fl oats safely back to Earth passed nating in two crane drops in preparation for live a milestone in September with completion of airdrop testing. the system acceptance review for the Orion Cap- The U.S. Army Product Manager Force Sus- sule Parachute Assembly System, or CPAS. The tainment Systems, or PM FSS, completed testing last major piece of paperwork certifying CPAS is in August of the G-16 cargo parachute, which will scheduled to be signed in March 2020 after Lock- replace the G-11 cargo parachute that was intro- heed Martin completes parachute mortar testing. duced 60 years ago. The G-16 can be deployed at Throughout 2019, the CPAS team at NASA’s John- lower altitudes because it has a new method for son Space Center in Houston also worked on in- controlling the canopy’s opening. The G-16’s con- stallation of the fl ight hardware into Artemis-1 struction can cut the cost over the life of the para- (formally known as Exploration Mission-1 or chute because of its modularity and simplifi ed re- EM-1), which is the uncrewed lunar orbital test pair procedures. Zodiac Parachute and Protection fl ight of the Orion capsule, expected to be launched America, now called Safran Parachute & Protec- in late 2021. tion America, developed the parachute with Fox CCDC SC, short for U.S. Army Combat Capa- Parachute Services under contract to the Army. bilities Development Command Soldier Center, In April, PM FSS also completed testing of the was focused during the year on developing tech- Extracted High- and Low-Speed Container Deliv- nologies to improve cargo and personnel airdrop ery System, or EHLSCDS, which includes the G-15 capabilities. CCDC SC conducted tests in March cargo parachute, 2.8-meter-diameter high-speed and June on self-guided cargo systems, including extraction parachute and A-24 cargo container. novel control methods and sensors to increase ac- EHLSCDS can deliver up to eight extracted CDS curacy in environments without GPS. Follow-up payloads at altitudes as low as 160 meters with tests were scheduled for October and December. indicated airspeeds of up to 426 kph and is com- Throughout March and July, CCDC SC conducted patible with both C-17 Globemaster III and C-130J modeling of fl ow behavior around various cargo Super Hercules cargo aircraft. Airdrops with high- aircraft to test the interaction with both cargo pay- speed extraction at low altitude reduces both ex- loads and human jumpers. Work on added safety posure on the drop zone and threat to aircraft. The for troop parachutes included the development of G-15 will be a partial replacement for the legacy an automatic activation device for the T-11 reserve G-12 until future payload certifi cation work will parachute employed during static line mass assault allow for the G-12’s full replacement. ★ operations and a smart snap hook that notifi es air- crew in the rare event of a towed parachutist. Contributors: Ricardo Machin, Kristen Ryan and In May, CCDC SC began developing key com- John Watkins

aerospaceamerica.aiaa.org | DECEMBER 2019 | 31 AIRCRAFT TECHNOLOGY, INTEGRATION AND OPERATIONS

Adapting air traffi c control for drones carbon dioxide emissions equivalent to planting 71,031 urban trees. and urban air mobility Government agencies opened doors to development of new types of aircraft and operations. BY DAVID THIPPHAVONG The FAA took steps toward establishing standards The Air Transportation Systems Technical Committee fosters improvements to for the return of civil supersonic fl ight in the U.S. transport systems and studies the impacts of new aerospace technologies. In June, it proposed streamlining the process for obtaining approval to fl ight test supersonic air- lobal airline industry profi ts are projected to craft. The FAA expects to publish a proposed rule dip from $30 billion in 2018 to $28 billion in for noise certifi cation of supersonic aircraft by 2019 because of a projected 14.3% increase March 2020. Besides noise, supersonic operations Gin fuel costs and a 5.3% increase in labor will also need to demonstrate safe integration into costs, according to the International Air Trans- the National Airspace System with existing and port Association. The return on invested capital of other emergent air traffi c operations. 7.4% is projected to be only 0.1 percentage points Beyond airline operations, NASA and its part- above the cost of capital. In North America, a net ners made progress toward building a framework post-tax profi t of $15 billion is expected in 2018, for safe, routine operation of small unmanned with a net post-tax profi t margin of 5.5%. The rel- aircraft systems in the airspace. In June, NASA, atively strong economic performance in North the FAA, the Nevada Institute of Autonomous Sys- America is attributed to the consolidation of com- tems and 18 industry partners completed Techni- mercial airlines, which has helped maintain high cal Capability Level 4 fl ight tests in Reno, Nevada. passenger and cargo loads, and increased an- It consisted of fi ve sUAS completing 150 missions cillary revenues that have blunted the impact of in downtown Reno and a nearby park. This test- higher fuel costs. ing was the fi rst of its kind with multiple sUAS NASA, the FAA, the National Air Traffi c Con- simultaneously fl ying beyond visual-line-of-sight trollers Association and industry have been de- operations in an urban environment. In August, veloping concepts and technologies to improve Technical Capability Level 4 testing continued in the handling of arrival, departure and airport Corpus Christi, Texas, to gather operational data surface traffi c. In July, NASA expanded opera- in a hot and humid urban environment and over tional testing for its integrated arrival, departure open waters. and surface, or IADS, program to the North Texas The UAS Technical Capability Level 4 fl ight area. NASA’s Airspace Technology Demonstration tests have also become important to development 2 project developed IADS to save fuel and emis- of UAM, short for urban air mobility , which indus- NASA researchers sions, reduce congestion on taxiways, and im- try, academia and government are increasingly work with software in prove compliance with controlled takeoff times pursuing. In October, NASA said recent work had the agency’s air tra c for managing overhead stream insertion. IADS focused on extending the UTM tests for sUAS to management laboratory has been tested at Charlotte Douglas Internation- UAM operations. Also in October, NASA released as part of Airspace Technology al Airport in North Carolina since September 2017 details of how industry could apply to test and Demonstration 2. and, in two years, saved airlines 1.4 million kilo- demonstrate technology in partnership with the NASA grams (3.1 million pounds) of fuel and reduced agency through a series of UAM Grand Challenge activities, with the fi rst event expected to occur in mid- to late 2020. In these activities, NASA provides the proving ground to facilitate the UAM community in testing and demonstrating their technologies and other capabilities that address foundational UAM safety and integration bar- riers. The UAM community will need to work together with the broader aviation community to demonstrate that UAM vehicles can be operated safely with regard to other vehicles in the air and people and property on the ground. ★

32 | DECEMBER 2019 | aerospaceamerica.aiaa.org AIRCRAFT TECHNOLOGY, INTEGRATION AND OPERATIONS

There were also a few notable fi rst fl ights among electric and small autonomy vehicles. In January, Boeing’s Aurora Flight Sciences subsidiary completed fi rst fl ight of its autonomous passenger air vehicle, an eVTOL confi guration, at its Virginia facility. Germany-based Lilium Jet’s fi ve-seat prototype, with tilting ducted fans, fl ew in May. H55’s battery-powered Bristell Energic, a more conventional confi guration manufactured by BRM Aero in the Czech Republic, made its fi rst fl ight in June from Sion, Switzerland. The aircraft has an endurance of 1.5 hours, targeting roughly an hour of pilot training fl ight time. Also in June, a modifi ed Cessna 337, the Ampaire 337, fi rst fl ew — its rear engine replaced with an electric motor, powered by lithi- Busy year for advancing emergent fl ight um-ion batteries. The objective is a confi guration with a piston engine optimized for cruise, using vehicle technology the electric motor to supplement for takeoff and climb. The California-based startup Elroy Air fl ew BY MICHAEL J. LOGAN AND MICHAEL L. DRAKE its Chaparral, an autonomous cargo VTOL drone, The Aircraft Design Technical Committee promotes optimization of aircraft in August. systems, including analysis of their future potential. In commercial transport aviation, Airbus launched its A321XLR, the longest-range variant Stratolaunch is the eveloper Franky Zapata fl ew a jet-powered of its A321neo family, targeting to achieve ranges world’s largest airplane hoverboard across the English Channel up to 4,700 nautical miles. In April, Embraer ob- by wingspan, stretching in August, crossing roughly where Louis tained regulatory approval from Brazilian, Euro- 117 meters across and Bleirot made the fi rst fl ight across the chan- pean and U.S. regulatory agencies for its E-195-E2. extending 73 meters D from nose to tail with a nel 110 years previously. In April, pilots evaluated The latest variant of the E195 demonstrated over maximum gross takeo Stratolaunch, a twin-fuselage, six-engine, satellite 25% lower fuel burn than its predecessor. Also weight of 590,000 launcher with a 117-meter wingspan, during a in April, the Polish-built Flaris LAR 1, a single- kilograms. nearly 2½-hour fl ight from Mojave, California, the engine personal jet, made its fi rst fl ight. Mitsub- Stratolaunch aircraft’s fi rst. ishi announced launch of its U.S. scope clause This year also saw steady development of ma- compatible SpaceJet M100 in June. The 76-pas- jor commercial and military programs and intense senger aircraft will be tailored to work within the activity around electric (or hybrid electric) pro- operational capacity and weight limitations of pulsion, autonomous and electric vertical takeoff many U.S. operators. Two new business jets were and landing, or eVTOL, aircraft (many of which are certifi ed during the year. Gulfstream achieved FAA aimed at the urban air mobility market). Type Certifi cation in June for its G600. In Septem- Governments continued to nurture potential ber, Cessna announced its FAA Type Certifi cation new aircraft technologies. In July, the European of the Cessna Longitude. Aviation Safety Agency released its fi nal Special On the military side, new developments in- Condition for VTOL aircraft. The rules apply guid- cluded fl ight of the Kratos XQ-58A Valkyrie, an ance for distributed propulsion vehicles with lift/ unmanned combat aerial vehicle, in March. The thrust powerplants, applicable to vehicles with demonstrator was developed under the U.S. Air up to nine passengers and a 7,000-pound (3,100 Force Research Laboratory’s Low-Cost Attri- kilograms) gross weight. NASA awarded funds table Aircraft Technology initiative. In March, for subsonic-transport electric propulsion stud- the Sikorsky-Boeing SB-1 Defi ant fi rst fl ew. The ies for potential electrifi ed aircraft propulsion, compound helicopter, with rigid coaxial rotors, is hoping to lay the groundwork for a future fl ight targeting the U.S. Army’s Future Vertical Lift pro- demonstrator. Its electric-powered X-57 Maxwell gram objective of vertical lift with substantially began ground runs of its Mod II in June, testing higher cruise speed and ranges than conven- the electric motors and propellers in an initial tional helicopters. Shortly after the Defi ant’s fi rst spin test. In August, the United Kingdom’s prime fl ight, in April, the An-24 replacement Ilyushin minister announced the Future Flight Challenge, Il-112V light military transport made its fi rst funding development of technologies for electric- fl ight. In September, Boeing’s MQ-25, an auton- powered passenger aircraft, cargo drones and ur- omous aerial refueler for the U.S. Navy, fl ew for ban air taxis. the fi rst time. ★

aerospaceamerica.aiaa.org | DECEMBER 2019 | 33 AIRCRAFT TECHNOLOGY, INTEGRATION AND OPERATIONS

Aviation automation in spotlight; This year also saw significant progress in unmanned aerial systems operations. A number of new-entrant evolution continues operators or companies have received special authorization through the FAA’s public-private BY TOM REYNOLDS partnership UAS Integration Pilot Program to The Aircraft Operations Technical Committee promotes safe and effi cient fly drones over people or beyond visual line of operations in the airspace system by encouraging best practices and sight. In April, Alphabet’s Wing Aviation was the information-sharing among the community and government agencies. first drone operator awarded an air carrier certi- fication. In March, UPS and Matternet made the he role of aircraft automation systems and first U.S. revenue-generating drone delivery of their certifi cation were major issues in avia- medical samples. NASA completed its technical tion operations this year after the high-pro- demonstrations of increasingly complex UAS T fi le crashes of Boeing 737 MAX aircraft in Oc- Traffic Management operations involving small tober 2018 and March 2019. In both cases, behavior UAS with Technical Capability Level 4 tests in of the Maneuvering Characteristics Augmentation Reno, Nevada, in May, and Corpus Christi, Tex- System, or MCAS, was implicated, and the aircraft as, in August. These demonstrations tested op- type was grounded worldwide in March. MCAS is eration of UAS in high-traffic urban applications designed to enhance pitch stability so that the MAX and included beyond visual-line-of-sight and behaves more consistently with other B-737 vari- contingency-management operations. ants. Redesign and recertifi cation of the system Companies also continued development of ur- were underway as of November. Despite the crash- ban air mobility, or UAM, vehicles and traffi c man- es, as of mid-October, the international aircraft agement concepts. In August, Volocopter became fatality rate was 20% below the fi ve-year average the fi rst company to fl y an electric-vertical-take- reported by the Aviation Safety Network. off-and-landing aircraft at an international airport The industry also continued planning for (Helsinki) while integrated into the air traffi c man- trajectory-based operations, which leverage agement system. NASA and Uber are continuing time-based management, information exchange their collaboration, and in October a joint simu- between air/ground systems and the aircraft’s lation activity used their respective automated ability to fl y precise paths in time and space. The traffi c management technologies to land simu- FAA has recognized that operations in challenging lated vehicles at the same virtual vertiport. In Oc- weather conditions will play a key role in achiev- tober, NASA kicked off its UAM Grand Challenge ing maximum benefi ts. In August, NASA started project, a public-private partnership focused on transitioning automation technology known as a series of increasingly complex demonstrations the Dynamic Routes for Arrivals in Weather, or of UAM vehicles and operations. On-demand he- DRAW, to the FAA to assist in this regard. DRAW licopter services were introduced in select loca- integrates advanced models of pilots’ behavior The fi rst commercial tions in the U.S. In July, Uber started Uber Copter around convective weather cells to predict the launch by a SpaceX services between New York City’s John F. Kennedy Falcon Heavy in April future aircraft trajectory and maintain trajecto- International Airport and downtown Manhattan, carried the Arabsat-6A ry-based operations that are currently discontin- satellite. while Airbus’ Voom started services across the San ued in these conditions. SpaceX Francisco Bay Area in September. They join Blade, which has operated in multiple cities across the U.S. since 2014. In terms of commercial space, 2019 saw the first revenue-generating launches of the SpaceX Falcon Heavy. Meanwhile, Blue Origin, Virgin Galactic and other commercial space companies edged closer to regular operations. In August, Virgin Galactic declared its base at Spaceport America in New Mexico ready for commercial operations, which it plans to start in 2020. The FAA is developing decision support systems to help facilitate safe, efficient and eq- uitable access to airspace as space and other new entrants evolve. ★

Contributors: Tamsyn Edwards, Gabriele Enea, Antony Evans and John Koelling

34 | DECEMBER 2019 | aerospaceamerica.aiaa.org AIRCRAFT TECHNOLOGY, INTEGRATION AND OPERATIONS

Raven Aerostar’s Flight 296 balloon ﬂ ew within 160 kilometers of Sioux Falls, South Dakota, for 20 days of its 40-day mission. Raven Aerostar

er spacecraft parachutes for crewed fl ight, part of the effort to return spacecraft directly to U.S. soil. By dropping the Starliner from a high-altitude balloon, the spacecraft is tested with the correct shape, mass, airspeed and altitude, a feat that is diffi cult to achieve by other means. Early in 2019, Near Space Corp. began working with U.S. and international customers on several high-altitude projects and increased the capabilities of its High Demonstrating navigation, persistence; Altitude Shuttle System, which is a lifting-body- shaped drone that can carry projects to a high al- carrying out spacecraft tests titude for testing. BY PAUL VOSS NASA’s Scientifi c Balloon Program continued work toward its goal of reliably launching The Balloon Systems Technical Committee supports development and 3,500-kilogram or heavier payloads to altitudes application of free-fl oating systems and technologies for buoyant fl ight in exceeding 35 km. In June and July, the program the stratosphere and atmospheres of other planets. carried out six training balloon infl ations in Pal- estine, Texas, to investigate prior anomalies. In- aven Aerostar balloons logged 7,500 fl ight fl ations done under varying weather conditions, days in the stratosphere as part of scientif- gross infl ations and with balloons of different ic, military and commercial missions, with sizes stepped through all of the phases of the Ran average fl ight duration of over 140 days. launch operations up to actual launch. Starting In June and August, a Thunderhead 208 balloon in late August, a Fort Sumner, New Mexico, fl ight demonstrated persistence in a designated area by campaign had its fi rst six of 12 planned launch- keeping within 100 miles (160 kilometers) of Sioux es of the Balloon-Borne Cryogenic Telescope Falls, South Dakota, for 28 days. After the balloon Testbed payload, or Bobcat. This is a new class exited the area, Raven Aerostar brought it back of payload looking at the far-infrared emission with wind steering and again put it into persistent lines to probe the chemical content, energetics mode to stay in the area around Sioux Falls. and physical conditions within the interstellar In June, the company demonstrated waypoint medium of the Milky Way. navigation with three balloons it launched from In August, CNES, the French space agency, led Maryland, fl ew across the country and brought four scientifi c zero-pressure-balloon launches down in a predesignated landing area in North- from the Timmins stratospheric base in Ontario, ern California. After traveling 2,100 nautical miles, Canada, including fl ights with a pointing gondo- the balloons landed within 80 km of each other. la carrying the French Pathfi nder for an Interna- In another demonstration of waypoint navigation tional Large Optical Telescope and the Canadian and persistence, Raven Aerostar launched three Super-pressure Balloon-borne Imaging Telescope. balloons from the California coast in July and In May and August, the Swedish Space Corp. per- directed them over the Pacifi c Ocean for specifi c formed drop tests from balloons with dummy re- missions. One was directed to fl y back to the Ra- entry bodies as part of the European Space Agen- ven Flight Operations Center in Sioux Falls; anoth- cy’s ExoMars mission that is scheduled to launch er was sent to Hawaii, where it performed a fl y-by in 2020. A 113,000-meter³ balloon with an 800 kg and was then directed to Sioux Falls; the third sys- payload and a 330,000 m³ balloon with a 2,000 kg tem was sent to Hawaii, where it performed per- payload carried out two drop tests at the Esrange sistence maneuvers. Space Center. ★ In February and June, Near Space Corp. completed the fourth and fi fth fl ights in a series of bal- Contributors: Russ Dewey, Mike Smith and loon-based drop tests to qualify Boeing’s Starlin- André Vargas

aerospaceamerica.aiaa.org | DECEMBER 2019 | 35 AIRCRAFT TECHNOLOGY, INTEGRATION AND OPERATIONS

Integrating various levels of autonomy was a consistent theme in atmospheric fl ight testing. Lockheed Martin’s Sikorsky division test fl ew its full-authority fl y-by-wire UH-60A Black Hawk. This marked the fi rst stage of Sikorsky’s optional- ly piloted vehicle, with future tests leading toward fully autonomous fl ight without a pilot on board. Further, a U.S. Air Force and Johns Hopkins Uni- versity team operated the Testing of Autonomy in Complex Environments system to enable artifi cial intelligence to control various aircraft. Research efforts to incorporate unmanned aircraft systems safely into the National Airspace Sys- tem continued. In August, a University of Alaska team tested UAS beyond visual line-of-sight without supplemental collision avoidance observers. Space vehicle, automation testing Also that month, the University of Kansas conducted fl ight tests to enhance the collision avoidance prevalent capabilities of UAS while minimizing trajectory perturbations. These projects seek to extend the BY KARL GARMAN AND ANDY FREEBORN capabilities of aircraft with varying levels of auton- The Flight Testing Technical Committee focuses on testing of aircraft, omy, including UAS and urban air mobility fl ights, spacecraft, missiles or other vehicles in their natural environments. or UAMs, over densely populated areas. Details of various UAM test programs emerged NASA tested the Orion he Stratolaunch aircraft was fl own for the throughout the year. For example, Aurora Flight Sci- launch abort system fi rst time in April in Mojave, California. It set ences fi rst fl ew its autonomous passenger air vehicle in July. Orion is part of a record for the largest aircraft measured by prototype in January, but it crashed in June on its NA SA’s Artemis program wingspan, surpassing the 1947 Hughes H-4 fi fth fl ight. In May, Germany-based Lilium conduct- and future plans for T missions to Mars. Hercules, or the “Spruce Goose.” Paul Allen, who ed the fi rst untethered fl ight of its electric-powered NASA died in October 2018, founded Stratolaunch Systems fi ve-seat Lilium Jet, which the company intends to to carry rockets for air-launch-to-orbit operations. produce for on-demand air taxi services. UAM proj- Multiple commercial space companies contin- ects such as these tend to demand confi dentiality, ued testing reusable suborbital vehicles. In May, with few details emerging from test programs. Blue Origin’s New Shepard launched for the 11th Boeing conducted fl ight tests on the 737 MAX time from a private site in Texas. This fl ight, the aircraft throughout most of the year, evaluating fi fth for this particular reusable booster, reached software fi xes for the aircraft’s control system. The an altitude of 65 miles. In February, Virgin Galac- testing centered on software and hardware related tic’s SpaceShipTwo completed its second test fl ight to MCAS, short for Maneuvering Characteristics above 50 miles altitude, one of several defi nitions Augmentation System, designed to ensure linear for the boundary of space. This fl ight also includ- control forces at high angles of attack. The testing ed the fi rst nonpilot crew member, continuing the program is part of requirements to return the air- company’s effort to develop commercial space craft to commercial service following fatal crashes tourism capabilities. In July, Virgin Orbit tested its in Indonesia and Ethiopia. Boeing 747-based satellite launcher, with the goal Boeing and Sikorsky, after a fi rst fl ight in March, of making air launch satellite operations routine. continued to expand the envelope of their SB-1 De- These emerging operations, driven by wealthy infi ant compound helicopter. The design is supposed dividuals from mostly nonaerospace backgrounds, to substantially increase cruising speed above that of demonstrate the prominent role of nontraditional current helicopters. In May, Sikorsky conducted the businesspeople in commercial space. fi rst fl ight of its HH-60W Combat Rescue Helicop- In July, NASA demonstrated the Orion space- ter, intended to replace the Air Force’s HH-60G Pave craft abort system during the Ascent Abort-2 test Hawk. These widely varied programs represent the fl ight at Cape Canaveral Air Force Station in Flori- broad nature of the fl ight testing fi eld, including new da. The test evaluated the Orion capsule’s ability to concepts and iterations of established aircraft. ★ escape from its launch vehicle during conditions of maximum dynamic pressure. Orion is part of NASA’s Contributors: Brent Cobleigh, Libin Daniel, architecture for future space exploration, which in- Ken Davidian, Shawn Keshmiri, Bruce Owens, cludes the Artemis program’s return to the moon. Derek Spear and Terry Weber

36 | DECEMBER 2019 | aerospaceamerica.aiaa.org AIRCRAFT TECHNOLOGY, INTEGRATION AND OPERATIONS

Hypersonics research accelerates developed ONR-UTA arc-heated wind tunnel “Leste” online. It is equipped with an arc heater producing across 3 continents nominal bulk enthalpies ranging from 1 to 10 MJ/ BY GREG JOHNSTON AND KEVIN KREMEYER kg at pressures up to 8 atmospheres. The facility is designed to operate with M=2, 4 and 6 nozzle inserts. The Hypersonic Technologies and Aerospace Planes Technical Committee The M=6 nozzle has an exit diameter of 23 cm. works to expand the hypersonic knowledge base and promote continued In Europe, HEXAFLY-INT, short for High-Speed hypersonic technology progress through ground and fl ight testing. Experimental Fly Vehicles-International project, continued to foster international cooperation in civil high-speed air transport research. HEXAFLY-INT, coordinated by ESA-ESTEC, is supported by the Eu- ropean Union within the 7th Framework Programme Theme 7 Transport. This year, the German Aerospace Center, DLR, completed experimental studies in its High Enthalpy Shock Tunnel Göttingen on the natural boundary layer transition and the effects of surface imperfections such as steps and gaps on the boundary layer of the HEXAFLY-INT hypersonic glider. The 1:2.6 scaled model of the hypersonic glider was tested at Reynolds numbers and Mach numbers that replicated the fl ight conditions along a section of the HEXAFLY-INT fl ight trajectory. Turning to Asia, the Japan Aerospace Exploration The O ce of Naval he U.S. Defense Department research en- Agency in April fi nished building a subscale hyper- Research/University of terprise continued to mature hypersonic sonic engine and fl ight experimental aircraft called Texas Arc-Heated Wind Tunnel in Arlington pro- technologies and concepts through a series HIMICO, short for High-Mach Integrated Control vides basic and applied of programs executed from within the Offi ce Experiment. Propulsion and wind tunnel testing research for arc-jet fl ow of the Secretary of Defense and in the service is scheduled at Mach 4 in 2020. The combustion characterization and Tbranches, consistent with the National Defense effi ciency and heat shield capability of the subscale thermochemical response Strategy and the hypersonic modernization priority hypersonic engine was evaluated in September by a of thermal protection materials in hypersonic of the Offi ce of the Under Secretary of Defense for direct-connect experiment at the University of Tokyo. fl ight conditions. The Research and Engineering. This year in India, the country’s first flight test tunnel, nicknamed The X-60A, a planned, above-Mach 5 test plat- of a scramjet powered hypersonic technology “Leste” after the hot and form, passed its critical design review in January, demonstrator occurred. dry winds of the Canary clearing the way for fabrication. Generation Orbit In China, a Mach 10 hypersonic glide vehicle Islands, was brought online in June. Launch Services Inc. is building the X-60A under was fl own in June, launched from a Dongfeng-17 University of Texas at Arlington/ contract to the U.S. Air Force Research Laborato- ballistic missile, as reported by the China Aerospace Luca Maddalena ry’s Aerospace Systems Directorate, High Speed Science and Technology Corp. Also, according to Systems Division. the U.S.-based National Defense magazine, the In the civil area, Boeing continued to make State Key Laboratory continued efforts to complete progress maturing the design of the hypersonic its higher-speed detonation-driven hypervelocity passenger airplane and propulsion system it re- tunnel for fl ows as fast as 12 km/s and Mach 25 with vealed in June 2018. Progress was also made toward accurate densities, heating surfaces of models with maturing enabling technologies, such as advanced spans as large as 3 meters up to approximately 7,700 titanium and composite structures, and elements degrees Celsius. In April, Xiamen University and the of an integrated propulsion/thermal management/ Space Transportation Co. launched a dual waverider power system. design with 3D inward-turning inlets to prove the Hermeus Corp., the Atlanta hypersonics startup, Xiamen Turbine Ejector-Ramjet combined cycle in June began testing the prototype turbine-based engine which operates from Mach 0 to 6. combined cycle propulsion system for its proposed Spaceplanes and hypersonic civil transport Mach 5 passenger aircraft. systems are being developed by countries across The University of Arizona completed a 15-inch the globe. ★ (38-centimeter) diameter Mach 5 Ludwieg tube to facilitate basic and applied research at the test and Contributors: Kevin Bowcutt, Jagadeesh Gopalan, evaluation scale in August. Barry Hellman, Jesse Little, Luca Maddelena, In June, the Aerodynamics Research Center of Masataka Maita, A.J. Piplica, Hideyuki Taguchi, the University of Texas at Arlington brought its newly Alexander Wagner and Michael White

aerospaceamerica.aiaa.org | DECEMBER 2019 | 37 AIRCRAFT TECHNOLOGY, INTEGRATION AND OPERATIONS

Freeriders Stefan Ager, Andreas Gumpenberger and Fabian Lentsch lower themselves by rope from an airship to begin their descent of 2,200-meter Austrian peak Kleiner Valkastiel. Mirja Geh and Lensecape Productions

occupancy cabin, the trips, according to OceanSky CEO Carl-Oscar Lawaczeck, will appeal to travelers wanting to contribute to “the development of sustainable travel.” In July, a team led by the International Insti- tute for Applied Systems Analysis published in the journal Energy Conservation and Management a scheme for using airships to usher in a hydrogen economy. A fl eet of automated, unmanned, hy- No “fl ight shaming” here: Airships drogen-fi lled cargo airships would circumnavi- gate the Earth with the jet stream for propulsion. leverage eco-friendliness On landing, they would offl oad their cargo and about 80% of their hydrogen (for terrestrial fuel) BY ALAN FARNHAM and then fl y home to pick up more freight. Lead The Lighter-Than-Air Systems Technical Committee stimulates development author Julian Hunt notes the plan would eliminate of knowledge related to airships and aerostats for use in a host of the expense and energy cost of having to liquefy applications from transportation to surveillance. hydrogen for transport. This year saw the birth of Zeppelin-skiing. In his may go down as the year “fl ight sham- March, three freeriders (one snowboarder and two ing” really got off the ground. In September, skiers) fl ew by Zeppelin from Germany to Austria, Alexandre de Juniac, head of the Interna- where they hovered over the 2,200-meter Kleiner T tional Air Transport Association, called the Valkastiel peak. They shimmied down a 50-meter trend — in which environmentally concerned rope, alighted on the mountain and began their travelers choose trains over planes — the biggest downhill run. Lensecape Productions captured threat to air travel in Europe and said it would it all on a four-minute video, which was viewed spread to the United States and other developed 6 million times. countries. Against this backdrop, advocates for air- Defense and border-protection agencies ships and airship-related ventures sang the envi- showed new commitment to fl ying tethered aero- ronmental merits of lighter-than-air systems. Car- stats for data collection and surveillance. Mary- ried aloft more by lifting gas than motors, airships land-based TCOM in September announced it had leave a dainty carbon footprint. Moreover, their lift won a $979 million contract from the U.S. Depart- and surface area make them promising candidates ment of Defense to support Army aerostats, in- for electric and solar-electric propulsion. cluding 23 deployed in Afghanistan, Iraq and North In April, England’s Hybrid Air Vehicles Ltd. an- Africa. ILC Dover built new envelopes for the U.S. nounced it would explore electric propulsion via a Customs and Border Protection agency’s Tethered partnership with Collins Aerospace and the Univer- Aerostat Radar System, delivering two of 420,000 sity of Nottingham, with funding from the United cubic feet (12,000 cubic meters) each and a third of Kingdom Aerospace Research and Technology Pro- 275,000 cubic feet (7,700 cubic m). gram. The objective of the project, named E-HAV1, Helium prices spiked for the third time since is to deliver a full-sized prototype 500-watt elec- 2006, creating gas shortages. Phil Kornbluth, tric motor for ground testing and eventual use on a president of Kornbluth Helium Consulting, in Au- production model Airlander 10. gust predicted shortages would persist through Swedish travel company OceanSky said in the end of 2019 and then would ease somewhat, June it had selected Airlander 10 as its preferred owing to increased production. platform for environmentally friendly trips to the The year marked the 90th anniversary of the North Pole starting in 2023. Up to 16 passengers Graf Zeppelin’s around-the-world fl ight, which set would make a three-day passage from an archipel- records for distance and duration that still stand, ago in Norway to the North Pole and back, landing and the 100th anniversary of R34’s double-crossing at the pole. Priced at some $79,000 per double- of the Atlantic (complete with stowaway and cat). ★

38 | DECEMBER 2019 | aerospaceamerica.aiaa.org AIRCRAFT TECHNOLOGY, INTEGRATION AND OPERATIONS

Future vertical lift competition on the SB>1, which is aimed at fulfi lling the Army’s need for the future long-range assault aircraft. The intensifi es; eVTOL designs proliferate S-97 Raider also continued to make progress, getting 55 hours of fl ight testing. Bell V-280 Valor BY ERASMO PIÑERO JR. tilt-rotor demonstrator testing continued apace, The V/STOL Aircraft Systems Technical Committee is working to advance surpassing 100 fl ight hours and achieving a speed research on vertical or short takeoff and landing aircraft. of 300 knots true air speed in March, proving the high-speed capabilities inherent in tilt-rotors. n a major vertical or short takeoff and landing This year saw the proliferation of pilotless ver- technology push as part of its modernization tical takeoff and landing vehicles for both private plans, the U.S. Army awarded contracts in April use and commercial transportation. In early Sep- Ito fi ve future attack reconnaissance aircraft tember, the online World eVTOL Aircraft Directory, competitive prototypes. It was the start of a large sponsored by the Vertical Flight Society, added its Department of Defense VSTOL acquisition pro- 200th electric vertical takeoff and landing aircraft gram not seen since the early days of the X-35 Joint concept. The directory was launched in 2017 and Strike Fighter concept demonstrator program. The has since been tracking new electric and hybrid/ companies are: AVX Aircraft, partnered with L-3 electric-powered VTOL aircraft in development by Communications Integrated Systems, both of Tex- aerospace companies, entrepreneurs and inven- as; Bell Textron Inc. of Texas; Boeing; Karem Aircraft tors around the globe. of California, partnered with Northrop Grumman In June, at the third annual Uber Elevate sum- and Raytheon; and Sikorsky. Each candidate was to mit in Washington, D.C., mock-up concepts gen- receive approximately $15 million this year and in erated excitement in the media and the public. It 2020. was an opportunity for the air taxi or urban air Sikorsky continued progress on its SB>1 mobility players to show their future products Defi ant joint multirole technology demonstrator, that they say will eventually meet the demands conducting the fi rst fl ight of the aircraft in March of urban air vehicles at costs far below tradition- at Sikorsky’s Flight Research Center in West Palm al helicopters. Boeing subsidiary Aurora Flight Beach, Florida. Sikorsky is partnered with Boeing Sciences conducted the fi rst fl ight of an eVTOL prototype for urban air mobility in January. The Sikorsky conducted vehicle is confi gured as an all-electric, four-seat- the fi rst fl ight of the SB>1 Defi ant joint multirole er with nine rotors. technology demonstrator The F-35 program began a period of inten- in March. sive production in 2018, but one of its production Sikorsky partners, Turkey, was no longer involved as of July. The 2020 fi scal year budget approved by Congress The Bell V-280 Valor tilt-rotor demonstrator in May authorized the purchase of 94 F-35s, 16 this year achieved a more than requested. The F-35C, the U.S. Navy speed of 300 knots true carrier-based version, reached initial operational air speed. capability at the end of February, accomplishing Bell Textron what the three services set out to do in 2001. Four Bell-Boeing MV-22B Osprey tilt-rotor aircraft from Marine Medium Tiltrotor Squad- ron 268 completed a trans-Pacif- ic fl ight from Okinawa, Japan, to Marine Corps Base Kaneohe Bay, Hawaii, in May, demonstrating the long reach and operational maturity of the V-22. The aircraft fl ew more than 5,300 nautical miles with minimum scheduled stops to refuel. ★

Contributors: Mark Alber, Paul Bevilaqua, Geoffrey Jeram, Mike Hirschberg and Paul Park

aerospaceamerica.aiaa.org | DECEMBER 2019 | 39 INFORMATION SYSTEMS

Industry disruption, transformation ed as of the end of October, suggesting a year-end total of eight orders — an extension of the depressed continue into fi fth year orders trend that began in 2015. Commercial GSO BY TOM BUTASH satellite orders totaled 19, 15, eight and fi ve in 2015, 2016, 2017 and 2018, respectively, after averaging 26 The Communications Systems Technical Committee is working to advance per year during the three years prior. Six additional communications systems research and applications. GSO orders were received for military applications, some from commercial operators, suggesting a con- A frame from the video feed of SpaceX vergence of the commercial and military markets. Falcon 9 upper stage In response, the industry increased its focus on shows a stack of 60 Star- an emerging class of small broadband communica- link smallsats moments tions satellites, or “micro-GSO satellites,” designed before they’re deployed. to fi ll capacity gaps too small to justify the time, SpaceX expense and risk of deploying a traditional 4- to 8-metric-ton GSO communications satellite. De- velopment of these 250 kg to 2,000 kg micro-GSO satellites was ramped up by startups Astranis, GapSat, Saturn Satellite Networks and the SWISS- atellite operators curtailed geosynchronous to12-Tyvak partnership and by established manu- satellite orders in 2019 for a fi fth consecutive facturers including Maxar (which received an Ov- year, a trend driven by overcapacity and fall- zon-3 order) and Boeing. This trend partially offset Sing prices in many markets, ongoing advanc- the decline in conventional GSO orders. es in and additions to planned non-geosynchronous In August, Northern Sky Research reported that orbit megaconstellations, and persistent market at least 16 companies, including Astrocast, Fleet, uncertainties. The specter of 50,000 NGSO broad- Kepler, Lacuna Space, Myriota and Sky and Space band smallsats (satellites with mass less than 1,000 Global, were developing NGSO constellations of kilograms) planned for launch over the next decade between 32 and 200 cubesats (the body dimen- — promising even greater capacity — further moti- sions of which are low multiples of 10-centimeter vated GSO operators to delay or cautiously restrict cubes) to provide “internet of things” communi- additional investments in their fl eets. This, in turn, cations services in remote markets. Although the led to the restructuring of GSO satellite manufac- revenue from these activities represents a small turing stalwarts, including Maxar Technologies (for- fraction of recent GSO market sales declines, the merly SSL) and Thales Alenia Space. The downturn initiatives nonetheless demonstrate the industry’s also prompted the acquisition of AsiaSat, Avanti and willingness to innovate to cost-effectively address Inmarsat by private equity interests; other operators, emerging opportunities. including APT Satellite and Sky Perfect JSAT, exam- Supporting this innovation, the launch vehicle ined alternative business models. industry, led by SpaceX and smallsat launch vehicle In March, Northern Sky Research reported developer Rocket Lab of California, continued to that capacity prices declined 18% over the pre- drive costs lower, reducing the expense of install- ceding year, extending declines of 35% to 60% in- ing additional communications satellite capacity. curred over the prior two years. The price declines As of mid-November, SpaceX had conducted nine were once again attributed, in part, to additional Falcon 9 and two Falcon Heavy launches in which high-throughput satellite launches. Exacerbating booster stages were routinely recovered. Rocket Lab these challenging market conditions, advances in conducted fi ve Electron smallsat launches in this planned NGSO broadband megaconstellations timeframe and, perhaps encouraged by SpaceX’s were seen throughout the year. In February, One- success, announced in August that it was develop- Web launched the fi rst six of its 648 smallsat constel- ing a reusable booster. During this pivotal month, lation, while in May, SpaceX launched the fi rst 60 of SpaceX revamped its smallsat ride-share program, its ultimately 42,000 smallsat Starlink constellation lowering launch costs to $5,000 per kilogram, about and another 60 in November. Further increasing 20% of the rate that had prevailed for decades. Inas- prospective capacity, Amazon’s Kuiper Systems much as estimates indicate as many as 100 smallsat in July fi led an application for FCC approval of its launch vehicles are under development worldwide, 3,236 satellite NGSO constellation comprised of the costs of space access and providing additional 784, 1,296 and 1,156 smallsats at 590-kilometer, 610 communications satellite capacity will undoubtedly km and 630 km orbital altitudes, respectively. continue to decline. ★ Against this backdrop, unsurprisingly, only seven competitive, commercial GSO orders were record- Contributors: Chris Hoeber and Roger Rusch

40 | DECEMBER 2019 | aerospaceamerica.aiaa.org INFORMATION SYSTEMS

This highly parallel reduced precision is employed in several low-end neural processing unit or tensor processing unit products released in the past 12 months. The Nvidia Jetson AGX Xavier 8G was available in August, and the Google Edge tensor processing unit was released in March. Some are targeted at mobile platforms such as drones, rovers and autonomous cars. Tesla Mo- tors began shipping its own “Full Self-Driving” chip in March. The neural processing and tensor processing units are an evolution of graphics processing units, which a decade ago morphed into physics engines and provided a radical boost for modeling and simulation. Neural processing units and tensor processing unit chips will eventually lead to more advanced autonomy in planetary explorers. Summit is designed to facilitate both physics simulation and artifi cial intelligence research. In June, Oak Ridge reported that a Monte Carlo sim- Transformations in computer ulation of a modular nuclear reactor ran 30 to 40 times faster on Summit than on the Oak Ridge’s architecture enable advances in Titan supercomputer introduced in 2012. It also ran the largest cosmological simulations to date, exploration autonomy providing comparison data for the Large Synoptic Survey Telescope, still under construction. BY RICK KWAN Summit also ran large computational fl uid The Computer Systems Technical Committee works on advancing the dynamics simulations. Reported at the AIAA Avi- application of computing to aerospace programs. ation Forum in June, the FUN3D simulator was used to run a CFD job of 6.5 billion elements and NASA’s Mars he architecture of terrestrial computing is 200,000 time steps. It previously took 2.9 months Helicopter fl ight in a metamorphosis that could eventually on a system of 5,000 Xeon Skylake CPU cores. On model — the aircraft prove useful in planetary exploration. At its Summit, using 552 Tesla V100 GPUs (a fraction of going to Mars with the core is the rapid adoption of data science what Summit has available), it took four days — 2020 rover — at the Jet T Propulsion Laboratory. — not only by scientists and engineers but even a 20-times speed-up. To get the same speed-up NASA by retailers sitting on stockpiles of business data. with CPUs would take 112,500 Xeon Skylake cores. And the underlying statistics and linear algebra Meanwhile, spacecraft computers are fi nd- increasingly employ shorter precision arithmetic ing their way onto atmospheric fl yers. In August, and logic for greater speed. NASA’s dual-rotor Mars Helicopter was attached The fastest supercomputer on the Top500 to the belly of the Mars 2020 rover. It is expected list in 2019 was the U.S. Department of Energy’s to make several test fl ights in the sparse Martian Summit at Oak Ridge National Laboratory in Ten- atmosphere and give operators a perspective of nessee. Introduced in June 2018, Summit is built rover surroundings that was not previously pos- on a combination of IBM POWER9 central pro- sible. The avionics stack includes a Snapdragon cessing units and Nvidia Volta graphics processing fl ight processor, TI Hercules high-reliability mi- units and is rated on High Performance Linpack at crocontroller and ProASIC rad-tolerant fi eld pro- 148.6 petafl ops. Beyond physics simulation, the grammable gate array. In June, NASA selected the Volta GPUs are positioned for machine learning Dragonfl y rotorcraft to explore Titan, a Saturnian and artifi cial intelligence research through the use moon with thick atmosphere and low gravity. A of small integers. radiation-hardened RAD750 computer will con- The vectors and matrices of data science and trol the avionics of this fl ying laboratory. As with machine learning aren’t necessarily single- and Earth-based drones, a tight control loop of sen- double-precision fl oating points. Much of it can sors, CPU and actuators must adjust the vehicle’s be done with half-precision 16-bit fl oats and small fl ight in real time and follow a mission profi le. 8-bit and 4-bit integers. For a given area of silicon But these fl ights are after months or years of dor- and power budget, smaller precision allows for mancy in space and targeting different environ- greater parallelism, hence increased speed. mental extremes. ★

aerospaceamerica.aiaa.org | DECEMBER 2019 | 41 INFORMATION SYSTEMS

Testing autonomy for lunar Gateway, based on the activities taking place and the health of the vehicle. The Gateway and vehicle will also Robonaut 2 and aviation respond to failures with additional safety-oriented actions, compared to those seen on the Interna- BY NATASHA NEOGI tional Space Station. Autonomy will enable the The Intelligent Systems Technical Committee works to advance the vehicle to assess the available resources and sys- application of computational problem-solving technologies and methods to tem statuses, return to a more functional state, aerospace systems. and adjust future activities. The combination of these capabilities will free up the crew and ground staff to focus on the most critical tasks. Additionally, two technology development demonstrations at Johnson were aimed at future Robonaut 2 autonomous logistics aboard the ISS. The fi rst demonstration, in June, focused on the challenges inherent in operating a robot aboard the ISS from the ground at Johnson. These include communication latency, bandwidth restrictions and expected losses of signal. Operators from a remote mission control operated Robonaut 2 while performing numerous autonomous tasks such as planning and taking steps across ISS handrails, locating and posing in front of objects, and interacting with those objects. A demonstration at Johnson in September focused on increasing the robot’s autonomous interaction in and around variable environments, including mapping unknown obstacles and traversing around them, building robust object detection, and working with those objects in a cluttered environment. In aviation, the Automatic Ground Collision Avoidance System, which has a set of autonomous decision-making and collision-avoidance algorithms to prevent jets from fl ying into the ground, was recommended for installation on the U.S. Air Force variant of the F-35 Lightning II this year — fi ve years ahead of initial plans. In June, the American Society for Testing and Materials published its fi rst technical report, “Au - tonomy Design and Operations in Aviation: Termi- nology and Requirements Framework (TR1-EB),” to guide the development of standards associated with increasingly autonomous fl ight. Administrative Robonaut 2, shown n preparation for its return to the moon in the Committee 377, comprised of four aviation-related performing a simple task, Artemis program, NASA demonstrated the abil- society technical committees, prepared the report, may be on its way back ity of the lunar Gateway to integrate with space- which provides defi nitions related to automation, to the ISS. craft, such as the Orion capsule and the human autonomy, artifi cial intelligence, machine learning NASA I lunar lander, and tested autonomy technology and many other relevant terms. It also discusses the in managing the Gateway’s vehicle systems in potential for levels of automation for aviation. The September at NASA’s Johnson Space Center in report will help standards committees produce a Houston. Autonomy will play an important role consistent and cohesive body of standards by pro- in operating the Gateway with its reduced data viding common terminology and a holistic frame- downlink capacity, communication delays, and work for discussing and determining requirements the combination of crewed and uncrewed periods for increasingly autonomous systems. ★ of operation. The September demonstration tested a surrogate vehicle’s ability to prioritize what Contributors: Kerianne Hobbs, Andrew Lacher, data is most important for the ground to receive Elizabeth Taylor and Alex Sobey

42 | DECEMBER 2019 | aerospaceamerica.aiaa.org INFORMATION SYSTEMS

Artifi cial intelligence and hypersonic sensor signals compared to other methods like physics-based models. We are already seeing this weapons drive sensing, fusion research innovation potential with the development of applications ranging from medical diagnosis to pre- BY RAYMOND S. SWANSON AND KENT R. ENGEBRETSON dictive maintenance.” The Sensor Systems and Information Fusion Technical Committee advances The greatest concentration of growth in new technology for sensing phenomena, fusion of data across sensors or sensors is in consumer applications with the most networks, and autonomous collaboration between information systems. activity in optical sensing across all applications. The other primary sensing emphasis has been on n February, the Pentagon released its artifi cial development of and defense against hyperson- intelligence strategy with the Joint Artifi cial ic weapons. The high speed and unpredictable Intelligence Center at the head of the effort. maneuverability of these weapons creates a dif- IThe Pentagon indicated that the Defense De- fi cult challenge for existing sensing architectures. partment will implement AI into existing process- Concerned with the rising threat of hypersonic es, digitization and smart automation. The doc- weapons from China and Russia, the U.S. Missile ument urges action “to protect our security and Defense Agency in 2018 awarded contracts for advance our competitiveness” in developing safe, concepts regarding the Space Sensor Layer, which ethical and secure AI solutions. The strategy says detects and tracks hypersonic threats from birth that JAIC will work with government, private sec- to death. In April, MDA asked Congress for an ad- tor, academia and international partners. ditional $108 million for hypersonic and ballis- AI has reshaped the sensing landscape. In tic space sensor development in fi scal 2020. The June, a new Lux Research report titled “Intelligent newly established Space Development Agency, Sensing: The Impact of AI on Sensor Capabilities” working collaboratively with MDA on the Space identifi ed the impact of AI on a range of sensor Sensor Layer, revealed in June its fi scal 2020 plans types, including optical, mechanical and acous- for a proliferated low Earth orbit satellite constel- tic sensors through analysis of more than 130,000 lation that would consist of about 1,200 satellites patents since 2012. across fi ve layers: a 200-satellite custody layer, a “With the advent and proliferation of artifi cial 658-satellite space transport layer, a 200-satellite intelligence technologies — concentrated in ma- tracking layer, a 200-satellite deterrence layer and chine learning — the capabilities of software-de- three advanced maneuvering vehicles. The space fi ned sensors are increasing at a breakneck pace,” layer will require not only increased sensor capa- Cole McCollum, research associate in sensors at bilities but also AI and improved communications Lux and lead author of the report, said in an ar- to process data and provide battle management ticle. “AI for analyzing sensor data enables far recommendations to commanders. more robust predictions and classifi cations using In addition to defense against hypersonic weapons, development of hypersonic weapons also poses signifi cant sensing challenges. In June, DARPA issued a solicitation for the Extreme Environment Sen- sors project. The goal is to develop and validate robust distributed instrumentation systems capable of with- standing the extreme heat, shock and vibration of hypersonic fl ight. ★

The Air-Launched Rapid Response Weapon is a hypersonic weapon prototype in development by Lockheed Martin under contract to the U.S. Air Force. Lockheed Martin

aerospaceamerica.aiaa.org | DECEMBER 2019 | 43 INFORMATION SYSTEMS

New focus on safety in software computers caused widespread delays. Though the problem was resolved, and computers were BY HANNAH LEHMAN up within the hour, the incident further empha- The Software Systems Technical Committee focuses on software engineering sized the importance of safety and redundancy in issues for complex and critical systems, including requirements, design, airline software. code, test, evaluation, operation and maintenance. Since 2010, the Air Force has been spearhead- ing the military’s only jam-proof satellite network, f there were a theme for software this year, it the Advanced Extremely High Frequency system. would be an increased focus on safe autonomy Through its work with the AEHF, the Air Force has and cybersecurity. amassed experience to begin production of a new- I Following the trends of previous years, er, cheaper, jam-resistant satellite communication military and commercial industries continued framework. In August, the Air Force launched the to increase investment in autonomy, especially fi fth AEHF satellite. learned autonomy. In March, Kratos’ autonomous A discussion of aerospace software would be infi ghter jet, the Valkyrie, completed its fi rst fl ight. complete without mentioning the Boeing 737 MAX This was the fi rst stage in an initiative to allow 8. In the span of six months, two 737 crashes result- pilots to focus on more critical items by making ed in 346 deaths. The crashes implicated MCAS, fully autonomous fi ghter jets that can process large short for Maneuvering Characteristics Augmenta- amounts of data rapidly without the human get- tion System, a program designed to prevent stall. ting inundated with information. In May, Boeing’s Though both aircraft that crashed had other initial Tapestry Solutions won a U.S. Air Force contract failures in sensing and deriving the angle of attack, worth as much as $259 million for software that the crashes brought to light issues with implement- will help troops plan missions, including points ing MCAS on the 737 MAX aircraft. After the planes for weapon launches. And in July, the Air Force in- were globally grounded in March, Boeing worked creased focus on autonomy as its tanker planning to create a software patch to prevent the problem software, designed to increase reliability in refuel- from reoccurring. As of November, the planes were ing, moved into testing. tentatively scheduled for a “phased ungrounding” The past year also saw more focus on cyberse- and reintroduction into commercial air transit. The curity in light of developments in airline vulnera- crashes and eventual pinpointing of the problem U.S. airline pilots are bility. The importance of hacking prevention was led to awareness about the FAA’s regulatory prac- expected to be training demonstrated in July when the U.K. Information tices, putting increasing pressure on primary, inter- on full motion simulators Commissioner’s Offi ce said it would fi ne British dependent safety reviews of all critical components such as CAE’s 7000XR Airways 183.39 million British pounds ($225 mil- in commercial aviation. Series once new software is approved for Boeing’s lion) for a 2018 data breach that affected half a mil- On a lighter note, 2019 marked the 50th anni- 737 MAX aircraft. lion of the airline’s customers. In March, technical versary of the Apollo 11 moon landing. As July 20 CAE issues in American Airports Corp.’s air-booking rolled around, NASA refl ected on the software that assisted Neil Armstrong and Buzz Aldrin in bringing the Eagle lunar lander down safely. A lot has changed since the 1960s in the software world. Com- puters no longer take up an entire room, embedded systems no longer have to be coded entirely in assembly, and in the 1980s, micro- processors were invented. However, the underlying purpose behind software remains the same. Just like the engineers of Apollo 11, engineers today strive to create effi cient programs that assist humanity and make activities enjoyable, reliable and safe. ★

44 | DECEMBER 2019 | aerospaceamerica.aiaa.org PROPULSION AND ENERGY

of the service module. The combined assembly was to undergo critical thermal-vacuum testing in late 2019 at NASA’s Plum Brook Station in Ohio and return to Ken- nedy Space Center in Florida in early 2020 to begin launch prepa- rations, including installation of the four solar array wings. The electrical power source on the Eu- ropean Service Module consists of four solar array wings comprised of three solar panels per wing. The solar array wings provide approximately 11.2 kilowatts of total power at 120 volts. The solar cells are the latest triple-junction technology, provided by New Mexico-based So- lAero Technologies. The solar array orientation is controlled by the two-axis solar ar- Radioisotope and solar-powered ray drive mechanism, which can swivel between minus 35 degrees and plus 25 degrees on the inner missions to Mars, moon, GEO axis and rotate fully from 0 to plus 360 degrees on BY GIANG LAM the outer axis to sun-track for maximum power. The four wings are folded against the crew module The Aerospace Power Systems Technical Committee focuses on the analysis, design, test or application of electric power systems or elements of electric adapter of the service module during launch and power systems for aerospace use. extend out 7 meters after launch into low Earth orbit. A Space Launch System rocket will launch The Multi-Mission ASA gave the U.S. Department of Energy the the Orion spacecraft on the uncrewed Artemis-1 Modular Solar Array, go-ahead in July to fuel the Mars 2020 rov- mission around the moon, targeted for before the unfurled at Lockheed er’s Multi-Mission Radioisotope Thermo- end of 2020. Martin’s Sunnyvale, Calif., electric Generator with plutonium dioxide Lockheed Martin’s A2100TR satellite bus with factory, powers the LM N 2100 satellite bus. in preparation for the launch to the red planet in fourth-generation 25-kW Multi-mission Modular Lockheed Martin July 2020. The MMRTG’s total mass is about 45 ki- solar Array, or MMA, launched and deployed on lograms, of which 4.8 kg is plutonium dioxide — orbit in February on the SaudiGeoSat-1/Hellas- the source of the steady supply of heat to convert Sat-4 communications satellite, designed for 15 into electricity for storage in two lithium-ion re- years of on-orbit operation. SaudiGeoSat-1/Hellas-

chargeable batteries. The electrical power system Sat-4 has electric propulsion Hall Current thrusters on the Mars 2020 rover produces about 110 watts powered by the MMA to transfer the satellite to its at launch and will decline a few percent per year geostationary fi nal orbit. The orbit transfer after for a 14-year operational life. Unlike with solar launch was completed on schedule, and the satel- panels, with the MMRTG engineers get the fl exi- lite was to enter service in late 2019 at its assigned bility to operate the rover’s instruments at night, orbit at 39 degrees east longitude. In addition to during dust storms and through the winter. this mission, a second commercial A2100TR sat- Aboard the Mars 2020 rover as one of the sci- ellite also powered by the MMA, Arabsat-6A, was ence payloads is the solar-powered Mars Helicop- launched in April on the fi rst Falcon Heavy booster ter, which was attached to the belly of the rover with a commercial payload. This satellite also used in August. The drone has a mass of 1.8 kg and will a 25 kW version of the MMA, modularly designed demonstrate fl ight stability on the surface of Mars to support both lower- and higher-power satellite and scout the best driving route for the rover. So- confi gurations. As of the beginning of October, lar cells will recharge its batteries, which are six this satellite was also operating nominally in its as- lithium-ion cells with a nameplate capacity of 2 signed orbit and was to enter service in late 2019. ampere-hours. A third lower-powered 13 kW MMA variant was The fi rst European Service Module, built by scheduled to launch in December at the earliest on Airbus Defense and Space, was mated to NASA’s an A2100TR satellite, JCSat-17. ★ Orion crew module in July. Built by Lockheed Martin Space, the Orion is attached to the front Contributors: John Gibb and Scott Billets

aerospaceamerica.aiaa.org | DECEMBER 2019 | 45 PROPULSION AND ENERGY

In May, NASA awarded the Power and Propul- sion Element contract to Maxar Technologies. In August, the 13-kW thruster was tested at full power. Launch was scheduled for 2022. Accion Systems Inc. of Massachusetts set a record for its electrospray thruster chip technology by fi ring a test unit for about 2,500 hours without intervention, achieving approximately 100 newtons of total impulse. The test concluded in May. Midyear, two of Busek’s small capillary-driven BET-300-P electrospray thrusters each exceeded 70Ns of total impulse, with the second test fi nish- ing in September. In July, an electric propulsion system integrated test was completed for the Psyche mission. The Maxar-Jet Propulsion Laboratory spacecraft, Explosive growth in electric propulsion which is scheduled for launch in 2022, will use a BY JAMES SZABO modifi ed SPT-140 HET system to rendezvous with the asteroid 16 Psyche in 2026. The Electric Propulsion Technical Committee works to advance research, In September, Aerojet Rocketdyne and sub- development and application of electric propulsion for satellites and spacecraft. contractor ZIN Technologies of Ohio fi nished assembling the fi rst fl ight string of the 7-kW NEXT-C A 100-kilowatt plasma s the year began, the European Space Agen- gridded ion engine system. In 2021, NEXT-C will plume from Ad Astra’s cy’s BepiColombo spacecraft continued to- fl y on NASA’s Double Asteroid Redirect Test, man- Variable Specifi c Impulse ward Mercury, propelled by QinetiQ gridded aged by the Johns Hopkins University Applied Magnetoplasma Rocket ion thrusters. The power processing units Physics Laboratory. engine is measured with A a series of probes. were developed by Airbus-Crisa. BepiColombo Also in September, Ad Astra Rocket Co. start- Ad Astra Rocket Co./AASEA was launched in 2018 and is scheduled to arrive ed a Variable Specifi c Impulse Magnetoplasma at Mercury in 2025. Also early in 2019, a BHT-200 Rocket, VX-200SS, testing campaign, completing Hall effect thruster, or HET, built by Busek Co. of a thermal steady-state 100-kW milestone. Ad Astra Massachusetts entered operational status on the also bench-tested to full power a 120-kW Tech- FalconSat-6 satellite, launched in December 2018. nology Readiness Level-5 power processing unit In February, four Aerojet Rocketdyne XR-5 from Aethera Technologies of Canada, measuring HET strings were launched on Hellas-Sat. In Au- 98% direct-current-to-radio-frequency effi ciency. gust, another four XR-5s were launched on Ad- Researchers at the University of Tokyo previ- vanced Extremely High Frequency-5. Arabsat ously reported developing and testing a three-unit 6A, launched in April, and another geostationary cubesat called AQT-D equipped with a 1U water spacecraft launched during the year will both em- Resistojet system called AQUARIUS. In Septem- ploy Aerojet Rocketdyne hydrazine Arcjets for ber, AQT-D was launched to the International North-South station keeping. Space Station. Also in February, OneWeb Satellites launched its NASA’s Jet Propulsion Laboratory in California fi rst six spacecraft out of hundreds planned. One- is developing the Ascendant Sub-kW Transce- Web’s low-power electric propulsion system, con- lestial Electric Propulsion System, or ASTRAE- ceived by Airbus, features xenon HETs and innova- US, small satellite HET system for interplanetary tive electronics and propellant regulation systems. missions, targeting a throttle range of 150 to 1,000 The electric propulsion subsystem is also part of the watts and 100-kilogram xenon throughput, peak Arrow platform used for other Airbus applications. system effi ciency greater than or equal to 50%, In May, the SpaceX Starlink constellation began to and dry mass less than or equal to 10 kg for the take shape with the launch of 60 operational satel- thruster, PPU, fl ow controller and gimbal. Mean- lites propelled by krypton-fueled HETs. SpaceX has while, a Busek BHT-600 HET duration test accu- received FCC approval to launch thousands more. mulated 6,300 hours at 600 W through November, High-power electric propulsion will soon be- demonstrating 860 kilonewtons of total impulse come part of NASA’s human exploration program. and 60 kg of xenon throughput. NASA’s Power and Propulsion Element, the fi rst In November, Busek delivered the fi rst planned element for the lunar Gateway, will carry low-power, iodine-fueled, gridded ion thruster two Aerojet 13-kilowatt Advanced Electric Pro- fl ight system. Two more were scheduled for deliv- pulsion System HETs and four Busek 6-kW HETs. ery before the end of the year.★

46 | DECEMBER 2019 | aerospaceamerica.aiaa.org PROPULSION AND ENERGY

Innovations made on NASA initiator, systems were 3D-printed at high rates with fi ne layer resolution (approximately 100 microns) 3D printing of propellants, cool gas and tailorable combustion characteristics. The adopted approach eliminates many of the hurdles generators commonplace in the industry and can be a trans- BY JOHN F. ZEVENBERGEN formative fabrication tool, while also supporting new research in materials development. The Energetic Components and Systems Technical Committee provides a The holy grail for metal particle combustion forum for the dissemination of information about propellant and explosive- would be to harness the enormous chemical based systems for applications ranging from aircraft to space vehicles. potential energy stored within metal fuel particles at time scales relevant to a detonation event. Diffusion controlled reactivity limits aluminum’s energy release potential but with the development of nanoparticles, time scales for diffusion-controlled kinetics could approach detonation. Nanoparticles cannot achieve reactivity at detonation time scales by themselves. This year, researchers at Texas Tech University and the U.S. Army’s Aberdeen Proving Ground in hanges to the production process for NASA This strand of solid Maryland continued improving the detonation standard initiators or NSIs, are never made propellant was manufac- time scales. They did this by capitalizing on a 2018 lightly. NSIs provide the initial pulse to begin tured with Purdue Uni- process breakthrough in which they transformed versity’s vibration-assist- critical thermal and mechanical processes ed printing technique. It’s the inert alumina passivation shell surrounding in both human-rated and uncrewed mis- shown burning at 10.34 the aluminum core into a highly oxidizer-rich Csions. For example, the “seven minutes of terror” megapascals with 300 salt called aluminum iodate hexahydrate, or required for landing a rover on Mars depends on milliseconds between the AIH, through surface chemistry. In May, the the NSIs functioning perfectly. frames. Texas Tech and Aberdeen team prepared the Purdue University The fi rst NSI production lot utilizing a new auto- aluminum particle surface with plasma surface mated manufacturing process was acceptance-tested treatments prior to AIH surface chemistry. The and delivered to NASA’s Johnson Space Center in plasma etches the surface layer so that AIH for- Houston in September by Chemring Energetic mation and concentration are more controlled Devices of Illinois. CED completed the qualifi cation and repeatable. Plasma surface treatment im- program in late 2018 to become the only certifi ed proves the particles’ safe handling and stability NSI producer in the world. under ambient conditions by producing a more The company’s qualifi cation included imple- consistent and repeatable coating. AIH-coated mentation and verifi cation of new manufacturing Al particles improve the detonation velocity of technology. Robotics were employed for bridgewire TNT by 30%. welding and energetic printing, which eliminated In July, ExxFire of the Netherlands fi nalized the traditionally operator-dependent processes and installation of 105 of its fi re-suppression systems improved manufacturing safety. Test results showed at Zee Media in New Delhi — the largest ship- the new process signifi cantly increased the manu- ment ever and a clear vote of confi dence from facturing uniformity and reduced the performance the market. Zee Media is the largest streaming standard deviation, especially in the actuation timing media company in India and part of the Essel at minus 251 degrees Celsius. Turning to additive Group. The ExxFire systems use cool-gas gener- manufacturing for solid propellant fabrication, ator technology from the Netherlands Organi- these techniques enable structural and compositional sation for Applied Scientifi c Research, or TNO, gradients that can improve combustion performance. for suppressing fi res in closed volumes such as However, until this year, additive technologies were server racks and switching cabinets in production only compatible with materials whose oxidizer mass facilities. The extinguishers produce nitrogen gas fractions were less than 60 volume %. Research by that lowers the oxygen level and suffocates the Purdue University this year led to the development fi re. While today’s high-pressure cylinders require of a new additive technique called vibration assisted maintenance, ExxFire’s cool-gas generators store printing or V A P. This direct-write technique has re- nitrogen gas in solid form in unpressurized cyl- moved prior material limitations. The Purdue group inders requiring no maintenance. ★ demonstrated in January the additive manufacturing of solid propellants with oxidizer volume fractions Contributors: Steve Son, Emre Gunduz, Michelle in excess of 76 vol.%. Furthermore, these material Pantoya, Hobin Lee and Harm Botter

aerospaceamerica.aiaa.org | DECEMBER 2019 | 47 PROPULSION AND ENERGY

Record-setting engine technologies damage observed in three to four years of fl ight time on the Airbus A320neo with just three months of pave way for third era of aviation testing. An average loading of dirt, determined by examining thousands of fl ights, replicated realistic BY MICHAEL G. LIST severe operating conditions. Dirt supplied at these The Gas Turbine Engines Technical Committee works to advance the science and concentrations mimics fl ight exposure, especially in technology of aircraft gas turbine engines and engine components. the eastern equatorial region of the world, specifi cally in Africa, Middle Eastern countries, India, China and as turbine engine manufacturers continued the Pacifi c Islands. developing technologies to improve engine Rolls-Royce of England tested an M250 turbine performance and durability and to reduce engine in a hybrid electric propulsion system at a Gmaintenance and environmental impact this test facility in Indianapolis in March. The test matured year, setting many records along the way. the hybrid electric system for future aircraft and In June, Pratt & Whitney of Connecticut completed served as a prototype for larger aircraft. The M250, an accelerated endurance test to assess PW1100G which typically powers helicopters, demonstrated geared turbofan engine hot-section durability. Half operation in series hybrid, parallel hybrid and tur- of the new airline passengers over the next 20 years bo-electric modes. are expected to come from the equatorial and Asian In June, Rolls-Royce and Aerofl ot of Russia cel- region, an area of signifi cant atmospheric dust and The Passport engine ebrated a record for a widebody engine in service. pollutants that affect engine life. Pratt & Whitney’s from GE Aviation was One of Aerofl ot’s Trent 700 engines completed 50,000 installed on a Bombardier newly developed severe environment testing in West engine fl ying hours without requiring an overhaul. Global 7500 that set Palm Beach, Florida, coupled with modeling technol- several speed records. The engine fi rst entered service in 2008 and powers ogy, expedited design enhancements by duplicating GE Aviation an Airbus A330 aircraft. GE Aviation of Ohio accrued 300 hours of fl ight time on the GE9X engine during a second wave of fl ight testing that concluded in May on GE’s 747 Flying Test Bed in Victorville, California. In total, GE fl ight-tested the GE9X for about 500 hours. GE also announced in July that the GE9X set a new Guinness World Records title after reaching 134,300 pounds of thrust (597 kilonewtons) in a November 2017 test at its Peebles, Ohio, test stand. GE Aviation announced in June at the Paris Air Show several records set by the 18,000-pound thrust (80 kN) Passport engine. Since beginning operation in December 2018, the Passport- powered Bombardier Global 7500 set multiple records for a business jet, including a speed record from New York to Los Angeles with fl ight time of 3 hours, 54 minutes and a top speed of Mach 0.925 in March. Bombardier, headquartered in Montreal also set a nonstop distance record with the Global 7500 of nearly 15,100 kilometers, flown between Singapore and Tucson, Arizona, in March. At the Paris Air Show, GE Aviation, Rolls-Royce and United Technologies Corp. (parent company of Pratt & Whitney) announced with several airframe suppliers a commitment to continue developing technologies to aggressively reduce emissions by 2050. Reductions, as stated in “The Sustainability of Aviation” are “enabled by advances in new architectures, advanced engine thermodynamic effi ciencies, electric and hybrid-electric propulsion, digitization, artifi cial intelligence, materials and manufacturing.” The announcement demonstrated the strong commitment of the aviation industry to rapid technology growth for decades to come. ★

48 | DECEMBER 2019 | aerospaceamerica.aiaa.org PROPULSION AND ENERGY

studies for a Mach-8 quiet wind tunnel to be constructed at the university. In July, Space Engine Systems Inc. of Edmonton, Alberta, which aims to build a single-stage-to-orbit scramjet vehicle, tested a complete engine at a 4-kilonewtons thrust scale, simulating conditions from takeoff to Mach 5 at an altitude of 98,000 feet. Performance of the connectionless titanium heat exchanger was demonstrated this year by removing 3.9 megawatts for just under 11 milliseconds. Heat transfer rates were increased by 40% by injecting nanoparticles in upstream hydrogen, confi rming the selection of Boron Carbide nanoparticles for rapid pre-cooling, shockwave control and augmented combustion performance. In Europe, the Institute of Space Propulsion at DLR, the German Aerospace Center, conducted experiments to investigate acoustic fl ow instabilities and the applicability of transpiration cooling Lighting fi res that can’t be extinguished systems in scramjets and the interaction between a wedge/fl ame holder and coolant secondary fl ow. BY GREG JOHNSTON, KHALED SALLAM AND ALEX CINTRON The DLR’s test facility in Lampoldshausen, can The High-Speed Air-Breathing Propulsion Technical Committee works to advance achieve combustion chamber inlet conditions the science and technology of systems that enable supersonic and simulating fl ight speeds ranging from Mach 5.5 hypersonic air vehicle propulsion. to 8. In January, the facility was upgraded with optical measurement capabilities; high-speed and The Aerodynamic and n August, the U.S. Air Force announced that a pseudo-color background-oriented schlieren. The Propulsion Tes t Unit Northrop Grumman-built air-breathing hyper- facility’s shock generator positions were explored at Arnold Engineering sonic engine set an Air Force record for thrust. for shock-boundary layer interactions using gaseous Development Complex in Tennessee, where a The supersonic combustion ramjet or scramjet hydrogen as a secondary coolant through different scramjet set a record. engine achieved over 13,000 pounds (58,000 porous wall segments made of sintered stainless U.S. Air Force Inewtons) of thrust during nine months of ground steel and carbon fiber reinforced ceramics. The testing by the Aerodynamic and Propulsion Test Unit cooling effi ciency of the hydrogen was increased at the Air Force’s Arnold Engineering Development by these interactions, while the refl ected/impinging Complex in Tennessee. shocks and interactions led to coolant ignition. The 5.5-meter-long engine demonstrated an DLR, in May, also focused on acoustically gener- unprecedented and remarkably large increase in ated instabilities in the combustion chamber fl ow, mass fl ow capacity, compared to the service’s last nozzle fl ow and inlet fl ow, where it was proved that major scramjet initiative, the fl ights of the X-51. “A screeching frequencies can cause issues to nozzle new engine with 10 times the fl ow of the X-51 would and inlet fl ows, but were mostly swallowed by the allow for a new class of scramjet vehicles,” said combustion chamber. Todd Barhorst, an Air Force Research Laboratory Turning to Asia, JAXA, the Japan Aerospace aerospace engineer, in an Air Force news article. Exploration Agency, in April finished building a Barhorst is the lead for the Medium Scale Critical subscale hypersonic engine and experimental fl ight Components Scramjet program. vehicle known as HIMICO, short for High-Mach Engineers were pleased that the engine endured Integrated Control Experiment. an accumulated half hour of combustion over the India’s Defense Research and Development course of the test program. Organization in June conducted a fl ight test of its The tests were made possible by a two-year Hypersonic Technology Demonstrator Vehicle, an upgrade to the Aerodynamic and Propulsion Test unmanned scramjet demonstration aircraft with Unit’s facility. a short operating capability of about 20 seconds. NASA, in September, completed fabrication The trial was carried out from Abdul Kalam Island of the Isolator Dynamics Research Laboratory in the Bay of Bengal. ★ at Langley Research Center in Virginia, which is capable of Mach 2.5 cold fl ow. Contributors: Todd Barhorst, Brandon Chynoweth, In June, Purdue University received a $5.9 million Robin Hunt, Jesse Kadosh, Masataka Maita, contract from AFRL for risk-reduction and design Sean Smith, Friedolin Strauss and Hideyuki Taguchi

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tinued to lead technology development for a Mars Ascent Vehicle intended to deliver samples from the surface of Mars into orbit. To this end, Whitting- hill Aerospace of California carried out full-scale motor testing of a wax-based fuel with MON-25, a mixed oxide of nitrogen, in April and July at the Mojave Spaceport. Test motors and oxidizer were conditioned to an assumed Mars operational temperature of minus 20 degrees Celsius. In this study, researchers achieved high-performance, stable burns with durations of 60 seconds. The Space Propulsion Group of California and Montana performed similar but smaller, sep- Advanced manufacturing extends arate tests in Butte, Montana, in January and April and had the same results. In addition, researchers operational boundaries of hybrids at Purdue University in August presented fi ndings BY TIMOTHY MARQUARDT AND JOSEPH MAJDALANI that they demonstrated the hypergolic ignition and multiple relights of a paraffi n-based hybrid The Hybrid Rockets Technical Committee studies techniques applied to motor with various hypergolic solids added to the design and testing of rocket motors using hybrid rocket systems. the headend of the fuel grain containing MON- 25. Tests showed good agreement with previously Virgin Space Ship irgin Galactic in February launched Virgin completed MON-3 testing, with some tests experi- Unity in space with three Space Ship Unity into space with a crew encing ignition delays. crew members aboard. of three aboard, 10 weeks after its fi rst trip The additive manufacture of advanced hy- Virgin Galactic Vbeyond the 80-kilometer space boundary. brid rocket motors to enhance burn rates and Powered by a hybrid motor that provided 320 effi ciencies continued to grow. This year, the Aero- kilonewtons of thrust for nearly 60 seconds, this space Corp. of California produced hollow liquid spaceship reached Mach 3.04 and an apogee fuel grains that used 3D-printed features to me- of nearly 90 km before returning to the Mojave ter the delivery of liquid fuels such as kerosene. Spaceport in California. This arrangement combined the capabilities of Researchers at Stanford University demon- liquid-engine performance with the safety and strated laser ignition of a hybrid fuel grain in a simplicity of hybrids. In the fi rst half of the year, lab-scale slab burner. They presented high-speed Aerospace Corp. fl ight-tested an advanced hybrid imaging results in July that identifi ed the under- rocket with these new liquid grains and a 54-milli- lying ignition mechanism as the entrainment and meter rocket motor. laser heating of small soot particles formed during In a separate program, Aerospace Corp. and fuel pyrolysis or chemical decomposition. A small Penn State continued development of a hybrid and lightweight laser diode, combined with a few propulsion unit for cubesats. Collaborators at simple optical elements, provided energy to a Penn State demonstrated start, stop and restart specifi c point on the fuel surface and heated soot capabilities of the unit early in the year before particles well beyond the temperature required returning it to the Aerospace Corp. for further for fuel pyrolysis. These particles then transferred development. The propulsion unit consists of a energy to the vaporized propellant mixture, ignit- 3D-printed solid fuel grain in a combustion cham- ing the motor. Experiments have confi rmed that ber integrated into and surrounded by a toroidal only those fuels that produced soot were com- oxidizer tank. The chamber/tank component was patible with this technique, but the method holds created with direct metal laser sintering, a form of promise for broader applicability. Tests in a sin- 3D printing that melts metal powder together with gle-port motor that aimed the laser at a small tar- lasers. This technique eases the production of in- get area of a compatible fuel embedded in a larger, tricate parts that possess the necessary thermal non-soot-producing fuel grain demonstrated ig- and mechanical properties for use in propulsion nition of the motor at both atmospheric and vacu- systems.★ um exit conditions. NASA’s Jet Propulsion Laboratory in California Contributors: David Dyrda, Andrew Cortopassi and and Marshall Space Flight Center in Alabama con- George Story

50 | DECEMBER 2019 | aerospaceamerica.aiaa.org PROPULSION AND ENERGY

2 supersonic aircraft programs reach The functional design and analysis of the inlet was completed in nine months, with the model fabri- testing milestones cation taking an additional three months. A short- ened development phase was made possible by BY JONATHAN S. LITT, TIM CONNERS AND JEFFREY D. FLAMM baselining the design from a known successful ex- The Inlets, Nozzles and Propulsion Systems Integration Technical Committee ample, Concorde’s wide-throat slot inlet; by judi- focuses on the application of mechanical design, fl uid mechanics and cious use of well-understood computational tools thermodynamics to the science and technology of air vehicle propulsion and methods along with the ability to upsurge and power systems integration. CPU demand as needed using cloud computing; and by restrained parametric surveys that allowed oom Supersonic made substantial prog- rapid convergence toward a high-performance, ress in the design, assembly and testing of though not necessarily optimized, design. its XB-1 supersonic demonstrator aircraft. Another noteworthy XB-1 development at BThis work culminated in engine ground Boom this year is the design of the vehicle’s testing, which concluded in February at the U.S. aerodynamically complex secondary fl ow path Air Force Academy in Colorado. The test demon- through the extensive use of computational tools. strated that measured inlet distortion levels were This involved modeling the throat bleed manage- acceptable for XB-1’s three GE J85-CAN-15 en- ment, engine bay cooling fl ow, pressure relief sys- gines. This achievement followed wind tunnel tems, integrated ejector nozzle and J85 variable testing of the inlet at the Boeing Polysonic Wind nozzle geometry. Ejector nozzle performance Tunnel in St. Louis in late 2018. was characterized using high-fi delity computa- The XB-1’s 2D hybrid compression inlet mod- tional fl uid dynamic models of the fully coupled el was designed for sustained Mach 2.2 operation secondary fl ow path. This effort improved ae- and uses modular fore and aft ramps, spill door ro-model fi delity and reduced uncertainty of the geometry and a wide-throat bleed slot that was overall vehicle mission performance. Along with based on Concorde’s. An aft-mounted auxiliary axisymmetric inlet concepts, the test-verifi ed 2D The X-59 Quiet Super- intake effectively reduces low-speed distortion, sonic Technology 9.5% inlet geometry and architecture are supporting although it is not required to meet fl ow demand. scale model was tested conceptual design studies for Overture, Boom’s Analysis of test data proved that high throat bleed at Mach numbers from commercial supersonic airliner. gives the inlet a modest amount of effi cient inter- 0.3 to 1.55 in the 8-by- In preparation for the X-59 Quiet Supersonic 6-foot Supersonic Wind nal compression and produced test-based pres- Technology critical design review, which occurred Tunnel at NASA’s Glenn sure recoveries across the operating range that met Research Center. in September, engineers from Lockheed Martin, or exceeded Concorde’s published performance. NASA General Electric and NASA completed NASA’s low-boom fl ight demonstrator inlet dynamic distortion test entry at the 8-by-6-foot Super- sonic Wind Tunnel at NASA’s Glenn Research Center in Cleveland in May. The test verifi ed the acceptability of the unsteady inlet distortion characteristics. The 9.5% scale model was tested at Mach numbers from 0.3 to 1.55. A mass fl ow plug was used to vary inlet mass fl ow. In- strumentation included an 80-probe rake at the aerodynamic interface plane: 40 pitot pressure probes and 40 high-response Kulite probes in side-by-side arrangement. ★

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Commercial Crew, engine tests gines to be used on the European Service Module supporting the Orion spacecraft for the Artemis-2 mark an active year mission. In Europe, Ariane Group qualifi ed its cryogen- BY DAVID J. COOTE AND VINEET AHUJA ic propulsion systems for the Ariane 6; the upper The Liquid Propulsion Technical Committee works to advance reaction stage Vinci engine passed its fi nal qualifi cation propulsion engines employing liquid or gaseous propellants. review in June, and the lower stage Vulcain 2.1 engine completed qualifi cation testing in July, ac- cumulating a total operation burn time of 13,800 seconds. Prometheus, a European Space Agency future launcher preparatory development effort to create a reusable LOX/methane engine, completed its subsystem’s manufacturing readiness reviews in 2019, and two demonstrator engines are planned for hot-fi re testing in 2020. JAXA, the Ja- pan Aerospace Exploration Agency, continued the development of the fi rst-stage LE-9 engine and the second-stage LE-5B3 engine for its fi rst H3 fl ight in 2020. The LE-9 engine completed engineering model hot-fi re testing in October and was to start qualifi cation testing in December at Tanegashi- The Space Launch ignifi cant progress was made this year in NA- ma Space Center. Testing of the Battleship H3 fi rst System’s core stage SA’s Commercial Crew program. In March, stage (two LE-9s), initiated in December 2018, was pathfi nder is positioned SpaceX launched to the International Space to fi nish in December at the Tashiro Test Complex. in the B-2 Tes t Stand at Station an uncrewed Dragon capsule on a The LE-5B3 fi nished qualifi cation testing in Febru- NA SA’s Stennis Space S Center in Mississippi. Falcon 9 rocket and then recovered the rocket. The ary at the Kakuda Space Center and Tashiro. Crews practice handling Falcon 9 fi rst stage that will launch the fi rst crewed In small thruster news, in January, Aerojet Rock- skills with a pathfi nder mission completed static hot-fi re acceptance test- etdyne’s monopropellant hydrazine propulsion before working with the ing in April. In other Commercial Crew activities, system powered the New Horizons spacecraft on real core stage. Boeing’s CST-100 Starliner completed key pro- the most distant solar system fl yby as it passed NASA pulsion system mission static testing in May, sim- within 3,500 kilometers of Kuiper Belt object Ulti- ulating on-orbit maneuvering and high-and-low ma Thule, 3½ years after its Pluto fl yby. In June, as altitude abort. Blue Origin fl ew the New Shepard part of a joint effort among Aerojet Rocketdyne, Ball suborbital vehicle in May in preparation for its fi rst Aerospace, NASA and the U.S. Air Force Research human fl ight. In May, Blue Origin unveiled its BE- Laboratory, the Green Propellant Infusion Mission 7, a highly effi cient, deep-throttling engine with was launched. It’s a 13-month demonstration of the restart capability that can power in-space systems. AFRL’s revolutionary “green” propellant, AF-M315E. In other commercial activities, United Launch In additive manufacturing activities, a full- Alliance’s next-generation launcher, Vulcan Cen- scale, 3D-printed high-pressure liquid oxygen/ taur, powered by BE-4 engines in the fi rst stage kerosene rocket engine combustion chamber and RL-10 engines in the upper stage, completed incorporating additive copper alloy GRCop-84 its fi nal design review in May. In January, Blue Ori- completed testing in February at NASA’s Mar- gin initiated the process to build the BE-4 engines shall Space Flight Center in Alabama for Virgin that will also be used to power its New Glenn rock- Orbit, delivering 8,900 newtons (2,000 pounds) of et. In August, Sierra Nevada Corp. announced it thrust in 24 60-second test fi rings. In April, Aero- would use the Vulcan for its Dream Chaser spacejet Rocketdyne also completed initial testing of craft, which completed its fi nal design review in its next-generation RL10C-X engine that uses a December 2018. 3D-printed injector and thrust chamber. In August, NASA’s Space Launch System core In April, the University of Southern California’s stage pathfi nder was fi t-checked in the B2 test Rocket Propulsion Laboratory designed, built and stand at NASA’s Stennis Space Center in Mississippi launched a rocket that passed the Karman line, in preparation for installation and hot-fi re testing believed to be a fi rst for a student team. ★ of the SLS Exploration Mission-1 core stage in May 2020. In February, NASA and Aerojet Rocketdyne Contributors: Colin Cowles, Steven Baggette, resumed hot-fi re testing of the RS-25 engines at Christoph Kirchberger, Scott Miller, Koichi Okita, Stennis. Aerojet Rocketdyne also delivered eight 490 Timothee Pourpoint, Dieter Preclik and newtons (110 pounds) of thrust R-4D auxiliary en- Chandrashekhar Sonwane

52 | DECEMBER 2019 | aerospaceamerica.aiaa.org PROPULSION AND ENERGY

propulsion that does not expel mass and only uses electrical power. CSU-Fullerton has been developing and testing Mach effect devices for 25 years as well as refi ning the theory of operation. Experiments in Germany, Canada and Italy and by multiple independent researchers in the U.S. are heavily focused on thrust balance calibration, experimental procedure, signal amplifi cation and corrections to the theory. The forces generated from these devices are generally less than 10 micronew- tons, but the true nature and source of the signals remains inconclusive. If the theory is found to be legitimate, Mach effect research could pave the way Nuclear propulsion planning focuses on for new propulsion physics and have applications well beyond space systems. modular, sustainable designs Researchers from Quantum Fields LLC in Illi- nois; the Institute for Advanced Studies in Texas; BY BRYAN PALASZEWSKI and the Center for Astrophysics, Space Physics and The Nuclear and Future Flight Propulsion Technical Committee works to Engineering Research at Baylor University in Texas advance the implementation and design of nonchemical, high-energy published new results in August on producing and propulsion systems other than electric thruster systems. accessing the negative quantum vacuum energy densities theoretically required by general relativity An artist’s rendering ince 2016, NASA has been exploring low- to produce novel propulsion schemes such as warp shows a modular and enriched uranium, LEU, reactors for nuclear drives and worm holes. This work noted the star- sustainable nuclear thermal propulsion or NTP. The LEU NTP tling fact that the theoretical quantum inequality thermal propulsion space vehicle for crewed project, led by NASA, is aimed at developing restrictions needed to generate such energies have missions to Mars. Hydro- a demonstrator to fl y before 2030 as a test for not been experimentally tested. The researchers gen fuel would be heated Screwed missions to Mars. Signifi cant conceptional analyzed the various technical schemes known by three nuclear fi ssion design evaluations and work were completed toward to produce “squeezed vacuum states” with the reactors and exhausted LEU NTP in 2019. technique called a “squeezed light” and discovered through converging- diverging nozzles to In February, the LEU NTP project received ad- that the restrictions were violated in the evaluated produce thrust. ditional funding and initiated several studies with published quantum optics squeezed light experi- Aerojet Rocketdyne industry and U.S. Energy Department labs. ments (represented by 25 years of published data). In May, Aerojet Rocketdyne refi ned its predicted The Casimir effect (with negative vacuum energy performance modeling of an LEU NTP engine. density in the space between the two Casimir cavity In July, researchers at NASA’s Marshall Space walls) is also expected to demonstrate experimental Flight Center in Alabama revisited demonstrator violation of quantum inequality, but this experiment vehicle concepts through various design cycles. has yet to be demonstrated in the lab because of In August, retired nuclear engineer David Black numerous technical challenges. The consequence of published a study concluding that low-enriched ura- the experimental violations of quantum inequality nium reactors, though higher in mass than a highly was that nature does not impose any truly signifi - enriched uranium reactor, can be designed to meet cant constraint on technologically producing and the mission, lifetime and operability requirements accessing negative vacuum energy density; this of NTP missions while simultaneously offering less result implied that there should be no roadblock to stringent safety, security and proliferation concerns. artifi cially producing a warp drive or a traversable Also in August, the Energy Department’s Sandia wormhole to achieve faster-than-light propulsion National Laboratories, Oak Ridge National Lab- for interstellar fl ight. oratory and Idaho National Laboratory worked In August, Stan Borowski presented a summary with Marshall and BWX Technologies of Virginia to of recent design studies in both nuclear thermal develop a path forward for LEU NTP fuel selection propulsion and in-situ resource utilization that and reactor design. could lead to viable experiments blending the two In other advanced propulsion areas, NASA’s Inno- technologies. This work will be critical for planning vative Advanced Concepts offi ce in April conducted and modeling missions using NTP. Borowski retired a Phase II midterm review for a proposal awarded in December 2018 from NASA’s Glenn Research in 2018 to California State University-Fullerton to Center after a 30-year career. ★ continue its experimental efforts examining the Mach effect, a theoretical form of gravitational Contributors: Eric Davis and Greg Meholic

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Advances in science and technology of to condition the exit fl ow for a downstream turbine. NASA researchers continued in-house numerical pressure gain combustion investigation and optimization efforts in resonant pulse combustion and RDE systems for applica- BY AJAY AGRAWAL AND DON FERGUSON tion to gas turbine engines. Additionally, under The Pressure Gain Combustion Technical Committee advances the an internal Center Innovation Fund, a rotating investigation, development and application of pressure-gain technologies detonation rocket engine nozzle optimization for improving propulsion and power-generation systems and achieving study and high-level rocket system benefi ts model new mission capabilities. development were initiated. In May, NASA solicited development proposals under Phase I Rocket Engine and Research, Development, Demonstration, and Infusion Early-Stage Innovations grants programs. In August, researchers at Purdue University reported development of an axial and outfl ow radial turbines suitable for small core RDEs. In an effort to assess the performance of the turbine-combustor interactions, an optically accessible test rig was developed in cooperation with Spectral Energies. In February, University of Michigan researchers identifi ed and quantifi ed regions of parasitic and commensal secondary combustion that affect the detonation wave in an RDE and identifi ed the presence of secondary waves. Secondary combustion and secondary waves couple together, ultimately A rotating or propulsion and power-generation systems, changing the stability and structure of the primary detonation engine detonation-based pressure-gain combus- detonation wave. was tested at Nagoya tion has the potential to deliver higher fuel In March, a team of researchers at the Univer- University in Japan in preparation for a effi ciency at reduced weight and footprint. sity of Alabama used time-resolved particle image sounding rocket This makes PGC attractive for terrestrial velocimetry to measure the exhaust fl ow of an RDE experiment planned for Fsystems, as well as aerospace applications such as operated on methane and oxygen-enriched air 2020. rockets and hypersonics. Recent investments have mixtures and demonstrated that the circumferential Nagoya University enabled quantitative fl ow and combustion diagnos- fl ow oscillations decreased by operating the RDE at tics and improved the technology readiness level by high pressures, and a downstream diffuser further transitioning laboratory concepts toward practice. homogenized the flow for turbine applications. Government, industry and academic institutions Activities at the Naval Postgraduate School from around the globe this year continued to advance April through June focused on RDE parametric PGC to a new and higher technical level. studies of combustor inlet area ratios, channel width The U.S. Air Force, Navy, Department of Energy and back-pressurization conditions to determine and NASA continued to support several PGC research pressure-gain performance. This was done through efforts. In June, the Air Force Research Laboratory and the application of equivalent available pressure Innovative Scientifi c Solutions Inc. conducted a ground which is an important parameter in evaluating the demonstration of a rotating detonation engine, or RDE, performance of a PGC device. capable of propelling a Long-EZ aircraft. This effort In Japan, Nagoya University, Keio University, demonstrated adequate thrust for takeoff and cruise Institute of Space and Astronautical Science of Japan operation, and acoustic measurements confi rmed a Aerospace Exploration Agency, and Muroran Institute safe noise level for ground operations. of Technology fabricated the prefl ight model of a The Department of Energy’s National Energy detonation engine system toward a sounding-rocket Technology Laboratory funded RDE development spacefl ight test scheduled for August 2020. efforts by Aerojet Rocketdyne with teammates from At Tsinghua University in Beijing, the effects Purdue University, University of Michigan, Univer- of a perforated wall on the hydrogen/air rotating sity of Alabama, University of Central Florida and detonation were studied emphasizing analysis of Southwest Research Institute. In May, the campaign acoustics and propagation stabilities. Experiments conducted hot-fi re testing of a 30-centimeter di- were also performed on kerosene/oxygen-enriched ameter natural gas and air RDE at Purdue’s Zucrow air rotating detonation. Using an Eulerian-Lagrang- Labs. Using multiple hardware confi gurations, the ian two-way coupling model, a 2D simulation of team demonstrated detonation combustion with a two-phase kerosene-air rotating detonation was low loss injector and an exhaust diffuser designed conducted using high-order numerical methods. ★

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Expanding ignition and combustion limits soot and fuel spray. Preliminary results with numerical simulations are encouraging, and the design and alternative fuels for the future must be numerically optimized and experimentally tested. The LFP injection system offers a route toward BY TIMOTHY OMBRELLO AND CLARESTA DENNIS the application of a premixed combustion mode The Propellants and Combustion Technical Committee works to advance for signifi cant advancement of aircraft propulsion. the knowledge and effective use of propellants and combustion systems Results were published at the ASME Turbo Expo 2019 for military, civil and commercial aerospace systems. and the AIAA Propulsion and Energy Forum 2019. Following the theme of lean combustor operation, ultiple milestones were achieved this an on-going project funded by AFRL studied lean year that demonstrated the unique ad- blowout, or LBO, and intrinsically fl ame stabilization. vantages of repetitive pulsed discharges Transient sequences of a laboratory-scale premixed for ignition in reacting fl ows relevant to fl ame were undertaken and identifi ed the role of a variety of engines. the swirling fl ow inner recirculation zone during MThe milestones were achieved through collabo- the LBO. Premixed simulations were performed ration among the U.S. Air Force Research Laboratory to resolve the fl ame-front thickness at nearly the in Ohio, the Technion-Israel Institute of Technology, Kolmogorov scales throughout the domain. The Oregon State University, Texas A&M University, Uni- overall dynamics and simulation results favorably versity of Central Florida and University of Dayton. compared with experiments. In January, infrared imaging thermometry Shifting to sustainable aviation fuels, or SAF, work showed that the synergy between pulses at frequencies this year under the multiagency National Jet Fuels greater than or equal to 10 kilohertz produced elevated Combustion Program, a European collaborative temperature ignition kernels, which explained the program, and a Navy program developed a two-tiered higher ignition probabilities and more rapid kernel prescreening methodology to predict and measure growth rates observed in previous years’ efforts. properties and, in turn, predict the effect of these Complementing the temperature measurements, properties on critical high volume and cost approval 50-kHz planar laser-induced fl uorescence measure- tests. ASTM D4054, the process for SAF approval is ments, in April, confi rmed that sustained elevated complex. The proposed prescreening methodologies concentrations of hydroxyl radicals are present in do not replace the established ASTM process, but developing ignition kernels for greater than or equal can provide a producer with increased confi dence to10 kHz pulsation rates. of approval and perhaps accelerate the process. The In July, optical emission spectroscopy measure- United Nations International Civil Aviation Organization ments revealed that pulsation frequencies of 250 kHz identifi es the market adoption of SAFs as the major nearly doubled the translational temperature over opportunity to mitigate the environmental impact of single pulse temperatures. The results thus far have aviation transportation; hence, there is market interest shown that high-frequency repetitive pulsing allows and importance to these new developments. enhanced and optimized ignition in reacting fl ows. In support of the SAF prescreening proposal, re- In a quest to decrease emissions for commercial searchers at the University of Dayton, Purdue University aircraft engines, a six-month computational effort and the German Aerospace Center, DLR, in September Hydroxyl radical funded by NASA’s Glenn Research Center in Ohio developed software to read gas chromatograph results planar laser-induced fl uorescence images of ended in February after developing the initial de- to predict critical fuel properties while requiring only ignition at 100 microsec- sign of a novel injection system, called Lean Fully microliters of volume, and researchers at Stanford Uni- onds after the last spark Premixed . This injection method achieves fully versity were planning to apply midinfrared absorption discharge in 10-pulse premixed combustion with the key advantages of capabilities to predict properties; manuscripts have bursts at 8, 10 and 20 minimizing NOx (nitrogen oxides) and eliminating been submitted for publication describing the new kilohertz pulse repetition frequencies applied in a process. A Commercial Aviation Alternative Fuels premixed methane-air Initiative technical guidance document (www.caafi . fl ow. Elevated hydroxyl org) posted in September summarized some of these radical concentrations results. Collectively, these prescreening results and for pulse repetition methodologies signifi cantly lower the barrier for early frequency greater than or equal to 10 kHz lead to SAF evaluations and offer the opportunity to expedite higher ignition proba- the approval process of novel SAFs. ★ bilities and more rapid kernel development to Contributors: Campbell Carter, Med Colket, Stephen enhance ignition across Hammack, Ron Hanson, Joshua Heyne, Gozdem Kilaz, a broad range of engine combustors. Joseph Lefkowitz, Patrick LeClercq, Paul Palies and U.S. Air Force Bastian Rauch

aerospaceamerica.aiaa.org | DECEMBER 2019 | 55 PROPULSION AND ENERGY

Northrop Grumman provided a modiﬁ ed Peacekeeper solid rocket booster and the abort and attitude control motors for the launch of the Orion capsule, seen here just after lifto for an in-ﬂ ight test of the launch abort system. Aerojet Rocketdyne built the jettison motor. Northrop Grumman

and testing of the Orion launch abort system, Solid rocket motor waves from around Northrop Grumman conducted several tests of other solid rockets. In April, the company con- the world ducted the second ground test of the newly devel- BY ORIE CECIL AND JOSEPH MAJDALANI oped 63-inch-diameter (160 centimeter) Graphite The Solid Rockets Technical Committee studies techniques applied to the design, Epoxy Motor. Known as GEM 63, it is a strap-on testing and modeling of rocket motors based on solid propellant grains. solid booster motor that will provide extra power to United Launch Alliance’s Atlas V. Additionally, in erojet Rocketdyne expanded this year with May, Northrop Grumman tested the fi rst stage of two new solid rocket motor facilities. In its new OmegA rocket in Promontory, Utah. The April, the company began construction on motor fi red for 122 seconds, producing more than A a 17,000-square-foot (5,100 square meter) 2 million pounds (8.9 million newtons) of thrust. engineering, manufacturing and development The European Space Agency, French National complex for large solid rocket motors in Camden, Center for Space Studies and Europropulsion col- Arkansas. The company opened a 136,000-square- laborated on a test for the fi rst qualifi cation model foot (41,000 square meter) advanced manufactur- of the P120C solid rocket motor in January. This ing facility in June in Huntsville, Alabama. stands as the second test of the P120C; the fi rst Beyond new buildings, Aerojet Rocketdyne was in July 2018. ArianeGroup and Avio co-devel- also achieved a hardware milestone in June when oped the P120C in support of the Ariane 6 and Ve- it delivered the jettison motor for Lockheed Mar- ga-C rockets. It is housed in a monolithic carbon tin’s Orion spacecraft. The jettison motor is refi ber case, making it the largest such rocket in the sponsible for separating Orion’s launch abort world. system from the crew module after a launch or China’s Smart Dragon-1 rocket was launched after the crew module has been detached from for the fi rst time in August. China Rocket Co. devel- the main vehicle and reoriented in the case of a oped Smart Dragon-1, which is designed to deploy launch failure. small commercial satellites (about 200 kilograms) Northrop Grumman also played its part in the into orbit using four solid-propellant stages. Also ongoing development of the Orion capsule. In July, faring from China, iSpace in July became the fi rst when Orion underwent a test of both the capsule private Chinese company to launch a payload into and launch abort system, Northrop Grumman pro- orbit. The payload consisted of several small sat- vided a modifi ed Peacekeeper booster to lift the ellites and was propelled into space on board the capsule and launch abort system, which exposed Hyperbola-1, which was comprised of four stages, both systems to atmospheric fl ight conditions. In the fi rst three using solid propellants. ★ addition to the booster, Northrop Grumman provided the abort and attitude control motors. Contributors: Clyde Carr, Michel Berdoyes and Apart from its role in the development Scott McHenry

56 | DECEMBER 2019 | aerospaceamerica.aiaa.org PROPULSION AND ENERGY

Progress made toward hydrogen- of hydrogen with incoming air. These combustors have been proposed to offer lower NOx emissions powered aircraft and biofuels and good fl ame stability limits. If successful, these combustors could pave the way for future hydro- BY BHUPENDRA KHANDELWAL AND KATHARINE COGGESHALL gen-powered aircraft. The Terrestrial Energy Systems Technical Committee works to advance the application On another front, researchers at Los Alamos of engineering sciences and systems engineering to the production, storage, National Laboratory identifi ed ideal algal strains distribution and conservation of energy for terrestrial uses. for producing cost-effective, refi nery-compatible diesel and jet fuel precursors. lobally, the decrease in fossil fuel reserves Biologist Christina Steadman of LANL designed and the advent of a climate emergency are a new suite of fl ow cytometry techniques and de- pushing society toward different energy scribed them in a November paper in the journal sources for propulsion. Renewable power Algal Research. These methods fast-track the process sources may always lack suffi cient ener- of identifying ideal strain candidates for genetic Ggy density for some aerospace applications, and enhancement. Steadman can track algal physiology therefore additional options need to be explored. and function within a given strain. Compressed or liquified hydrogen has high Beyond the identifi cation of strains well-suited specifi c energy and energy density, making it a good for bioengineering, Steadman’s techniques also candidate for powering gas turbines in aircraft. aid in evaluating how algae strains react after bio- However, due to emissions and onboard storage engineering takes place. Complicated metabolic challenges no more study has explored the use of interactions cannot always be predicted. hydrogen as an aviation fuel since the multinational Also, Amanda Barry, a LANL biologist and pro- CRYOPLANE Project of the 1990s and early 2000s. gram manager, furthered her groundbreaking 2018 This year saw a renewal of interest in hydro- research by identifying additional algaes that have the gen as a potential source of propulsive power for ability to break down raw plant biomass , revealing aircraft. In a variety of conference presentations this characteristic to be more common across algae and journal papers between June and September, genera than previously thought. The Los Alamos Na- researchers from the University of Sheffi eld and Barry’s 2018 research on Auxenochlorella proto- tional Laboratory’s pond Cranfi eld University in the United Kingdom and FH thecoides, described in the September 2018 issue of simulator photobioreactor Aachen University of Applied Sciences in Germany Algal Research, established the fi rst report on direct mimics outdoor condi- proposed new micromix-based combustor concepts degradation and utilization of raw plant hemicellulose tions in algae cultivation, in which thousands of small fl ames would maintain enabling rapid-paced by a freshwater alga. She showed that the algae can energy security research. combustion. Such designs would produce limited grow, both phototrophically and heterotrophically, by Los Alamos National Laboratory NOx (nitrogen oxide) emissions from the burning feeding on dried and chopped switchgrass (common lawn residue). Feeding algae with lawn clippings could help make algal biomass production economical, given that lawn clippings are inexpensive or free. The costs of producing biomass from algae compared to the current cost of fossil fuels has been the limiting factor for viable biofuel competition. Both Stead- man’s bioengineering approach and Barry’s all-natural approach promise increased algae biomass and lipid production, which are needed to produce diesel and jet-fuel precursors, at a reduced cost. ★

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sonalized treatment, such as gene therapy, to prevent or reverse adverse effects. Immunity has long been a concern for astronauts, not least because microbes reproduce differ- ently in microgravity. Researchers are also learning more about the human immune response in space; for example, the twins study found that a fl u vac- cine can be administered and effectively provide immunity in space. This encouraging result is offset by fi ndings that Scott Kelly’s immune response and infl ammation were negatively affected by the stresses of landing and reintroduction of Earth’s environment after long-term adaptation to spacefl ight. Telomeres are the critical end sections of our chromosomes, thought to be related to aging and other biological processes. Scott Kelly’s white blood cell telomeres unexpectedly lengthened in space, but were then shorter than their original length upon his landing and eventually returned to baseline length after a few months on the ground. These results suggest that long-term spacefl ight may affect aging and other aspects of genetic stability. NASA is planning follow-up studies to further confi rm and characterize these pre- Kelly twins’ year-in-space study viously unknown effects. Researchers also found that signifi cant cog- yields data nitive degradation develops over a year in orbit and then remains after months of adaptation BY JONATHAN G. METTS back to conditions on Earth. Metrics that don’t The Life Sciences and Systems Technical Committee advances technologies seem to recover quickly, if at all, are particularly required to keep people healthy and safe as they explore space. concerning to NASA mission planners, who need to keep a fl ight crew healthy and savvy for Mars Astronaut Scott Kelly n April, the journal Science published multidis- surface operations after enduring several months self-administers a fl u vac- ciplinary results of “The NASA Twins Study: A in deep-space transit. cine on the International multidimensional analysis of a year-long human In October, NASA sought industry feedback Space Station as part of spacefl ight.” This broad suite of bioastronautics on plans to eventually outsource its new space- NA SA’s Twins Study. I NASA research focused on a pair of identical twins, both suit for lunar and planetary exploration, named now retired astronauts, Scott and Mark Kelly. For xEMU. The agency is committing to build and the 27 months of study, numerous samples and test the fi rst suits of this new design, already metrics were voluntarily collected from the broth- many years into development. These initial, NA- ers before, during and after Scott’s 340-day mission SA-produced suits will be fl own on ISS in 2023 aboard the International Space Station. The par- and are scheduled to be worn when humans once ticipation of both twins allowed Mark to become again walk on the moon as early as 2024, as part a genetically identical baseline against which to of the Artemis 3 mission. Looking beyond, NASA compare the spacefl ight-induced changes that plans to hand over subsequent suit production to Scott experienced throughout his year in space. industry partners, and its solicitation addresses The study examined epigenetic changes, commercialization of suit upgrades, tools, vehi- which are the body’s reaction to an environment cle interfaces and spacewalk opportunities for through selective expression of genes. Post-land- non-NASA customers. ing samples helped researchers learn that while NASA astronauts Jessica Meir and Christina living in space does affect gene expression in myr- Koch performed the fi rst all-female spacewalk iad ways, most of those changes reverse within in October. They installed a new power charging a few months of returning to Earth. Conversely, unit outside the ISS. NASA had planned an all-fe- some epigenetic consequences of long-duration male spacewalk for March, but those plans were spacefl ight appear to be permanent. Identifying deferred for lack of a second medium-size torso which genes are most affected, and when those piece of the American spacesuit, known as the ISS expressions onset and stabilize, may lead to per- Extravehicular Mobility Unit . ★

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burned fuel with inert gas to study the quantity of soot produced under different fl ame conditions. The soot clusters produced by a fl ame glow yellow when hot and they grow larger in microgravity because the soot remains within the flame longer. The research is aimed at reducing pollutant emission in practical terrestrial combustion and spacecraft fi re prevention research. Microgravity effects on humans are of concern for long-term resi- dence on the ISS and potential deep space missions. Scientists at the University of Washington School of Pharmacy and UW Medicine, with collaborators, designed an experiment to study microgravity effects on human kidney health, specifi cally on segments of renal tubules (the renal tubule receives plasma fi ltrate and processes it into the urine). The researchers launched the Kidney- on-a-Chip Space Project to the ISS in May. The 24 credit-card-size chips have fl uid microchambers that are Microgravity research advances lined with human-derived kidney cells for examining two segments of the renal tubule with different physical, biological and material aspects of fi ltrate absorption. Experimenters will sciences analyze the chips upon their return to Earth. March marked the third anniversary of additive BY SUNIL CHINTALAPATI manufacturing on the ISS, where machinery has The Microgravity and Space Processes Technical Committee encourages produced 115 tools. Additionally, this year saw the the advancement and public awareness of low-gravity studies in physics, launch of an innovative 3D printer by Techshot Inc., materials, biological sciences and related fi elds. an ISS commercial facility partner, and nScrypt, a manufacturer of industrial 3D bioprinters and elec- A fl ame ignited in the stronauts on the International Space Sta- tronics printers, to manufacture human tissue in Combustion Integrated tion carried out about 300 microgravity microgravity. In August, astronauts began operating Rack on the International experiments this year. The commercial the 3D BioFabrication Facility, which “uses adult hu- Space Station to investi- and research experiments included those gate the amount of soot man cells (such as stem or pluripotent cells) and adult that is produced. The in physical and life sciences and advanced tissue-derived proteins as its bioink to create viable soot clusters glow yellow Amanufacturing. tissue,” according to a Techshot news release. Manu- when hot. These clusters Scientists from NASA’s Glenn Research Center in facturing of soft human tissue on Earth is hampered grow larger in micrograv- Ohio oversaw the fl ame design experiment, which due to soft tissue collapse in gravity. Experimenters ity than on Earth because aims to optimize oxygen-enriched combustion by the soot remains within aim to use the 3D BioFabrication Facility to print soft the fl ame longer. examining the production of soot. Flame design is tissue and strengthen cell-culturing systems before NASA part of the Advanced Combustion via Microgravity sending them back to Earth to potentially create Experiments. The fl ame design experiment was patient-specifi c replacement tissues. conducted in the Combustion Integrated Rack, This year also marked the 15th fl ight oppor- or CIR, which provides an isolated environment to tunity for the Students Spacefl ight Experiment conduct combustion-related experiments. A fl ame Program. Each year, this program gives hundreds in reduced gravity tends to be spherical. While on of students a chance to design experiments to fl y Earth, hot gases from the fl ame rise, while the cooler aboard the ISS. This year, 3,683 students submitted dense gas is pulled down by gravity. proposals and 41 experiments fl ew to the ISS. A Astronauts conducted the flame design ex- total of 23,117 students from fi fth grade through periment from March to October. Experimenters college were involved. ★

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A camera aboard the MarCO-B cubesat snapped this image of Mars as it ﬂ ew by the red planet in November 2018 after completing its telemetry relay contribution to NASA’s Mars InSight mission. In Feb- ruary, NASA announced that both MarCO satellites had gone silent. NASA/JPL-Caltech

Small satellites deliver science, of its prototype small satellites on a Soyuz-ST-B Fregat mission. The company has a planned con- communications, commercial missions stellation of 648 microsatellites of 125 kg each. BY MARTIN LINDSEY The fi rst six satellites were dedicated to connect- ing remote schools throughout the world. OneWeb The Small Satellite Technical Committee works to advance the science and also announced in September that it would be engineering of satellites, launch vehicles and ground systems to enable the the fi rst company to provide 300 gigabytes-per- development of small and highly capable spacecraft. second communications capacity to Arctic re- mall satellites arrived big time on the stag- gions above 60-degrees north latitude by late 2020. es of global commerce and interplanetary Although the communications satellites would not research in 2019, and many anticipated technically be small satellites at 227 kg each, One- Sregulatory changes promise to further has- Web announced its Arctic plans after SpaceX began ten the revolution. launching its global internet constellation, Star- Several companies expanded their commer- link, in May with 60 satellites of a planned constel- cial offerings focused on information derived from lation in the thousands. frequent Earth observations in many phenome- Small satellites continued expanding their in- nology. Although the fi rst synthetic aperture radar terplanetary research contributions as well. The small satellite demonstration missions occurred Mars Cube One, or MarCO-A and -B satellites, NA- in previous years, this year saw the fi rst realization SA’s fi rst interplanetary cubesats, completed their of their commercial potential. The 70-kilogram mission in January providing near real-time te- ICEYE X3 launched in May, and X4 and X5 launched lemetry relay of Mars InSight’s entry, descent and in July, providing 1-to-10-meter resolution X-band landing. MarCO-B, carrying a commercial camera SAR imagery for government and commercial cus- with a fi sh-eye lens, returned a stunning “farewell” tomers. San Francisco-based Capella Space is also image of Mars after completing its primary mis- poised to provide ubiquitous SAR imagery to the sion. The fi rst commercial lunar lander mission, commercial market. With its fi rst demonstration Beresheet at 150 kg, made it to lunar orbit in April launch in December 2018 and fi rst commercial but suffered an engine failure on descent to the lu- launch scheduled before the end of 2019, Capella nar surface and crashed upon its attempted land- had raised $50 million as of June toward realizing ing in Mare Serenitatis. its mission of fl ying 36 satellites with a resolution This past year also saw quicker launch cadence of 50 centimeters and one-hour revisit rates. San and a promising increase of launch opportunities Francisco-based companies Planet and Spire and for small satellites. As of October, Rocket Lab had Virginia-based companies Black Sky and Hawk- launched fi ve small-satellite-dedicated missions in Eye360 and several other commercial ventures ex- 2019, deploying 15 small satellites. Virgin Galactic’s panded their on-orbit constellations and fi rmly es- Launcher One was slated for its initial test fl ight be- tablished the commercial market for imagery and fore the end of 2019. ★ business intelligence products. Global broadband internet took two large steps Contributors: Scott Palo, Bryan Rogler and forward in 2019. In February, OneWeb launched six Michael Swartout

60 | DECEMBER 2019 | aerospaceamerica.aiaa.org SPACE AND MISSILES

Portals to lunar exploration take shape 20 years.” It comprised two modules: a dedicated habitat and an airlock that could provide addi- BY BARBARA IMHOF AND THEODORE W. HALL tional living and working volume. The modules The Space Architecture Technical Committee focuses on the architectural would ride to lunar orbit aboard NASA’s new Space design of the environments where humans will live and work in space, Launch System under the Artemis program. including facilities, habitats and vehicles. Sierra Nevada Corp. opened its model in July, also at Johnson. It adopted infl atable technology originally pioneered by NASA and Lockheed Mar- tin, subsequently licensed by Bigelow Aerospace, and for which the patent has now expired. Sierra Nevada dubbed its module the Large Infl atable Fabric Environment. Fully infl ated, it measures 8 meters (27 feet) in diameter and length, providing about 300 m³ of pressurized volume, divided into three decks parallel to the cylinder axis. Despite its large deployed volume, it could pack into a 5 m payload fairing on a commercial rocket. Considering the merits of all of the concepts demonstrated, in July NASA awarded a sole- source contract for a minimal habitation module to Northrop Grumman, stating that it was “the only NextSTEP-2 contractor with a module design and the production and tooling resources capable of meeting the 2024 deadline,” in view of the progress already made in Northrop’s Cygnus spacecraft development. A design for the unar Gateway development was a nexus of Nevertheless, Bigelow Aerospace demonstrated “Moon Village,” a concept space-architecture activity this year. In the its B330 module in August and September at its fa- for the fi rst full-time United States, fi ve contractors constructed cility in Nevada. The largest of all of the NextSTEP human habitat on the full-scale habitat ground-test models for entrants, the module provides 330 m³ of pressur- moon. L Skidmore, Owings & Merrill LLP evaluation at several locations as part of the Next ized volume yet packs for launch within a 5 m pay- Space Technologies for Exploration Partnerships load fairing. A volumetric demonstration unit open program, or NextSTEP. In Europe, consortiums of to the press was built in steel rather than infl ated space systems companies advanced designs for liv- fabric in order to sustain the Earth gravity loads. ing in deep space. Meanwhile, the European Space Agency and its Lockheed Martin was the fi rst to open its hab- contractors continued plans to provide interna- itat model for evaluation, in February and March, tional elements to the Gateway. In October, Air- at NASA’s Kennedy Space Center in Florida. Lock- bus completed study contracts for two elements: heed based its concept on a repurposed “multi- I-Hab, the international living and research mod- purpose logistics module” from the space shuttle ule; and Esprit, the infrastructure module that in- era. Modularity to support a diversity of missions cludes a propellant storage and refueling system, was a top priority. interface to payloads and a scientifi c airlock. Thales Northrop Grumman Innovation Systems was Alenia also in October separately completed study next, in April and May, at NASA’s Johnson Space contracts for the same two elements. The space ar- Center in Texas. Northrop derived its concept chitecture fi rm Liquifer Systems Group, based in from its Cygnus cargo spacecraft, which is already Vienna, worked on a subcontract from Airbus to in production. The company has made progress to support the habitat engineering confi guration. evolve Cygnus into a habitable spacecraft, includ- Besides the orbital Gateway, the lunar surface ing the design and placement of docking ports was the focus of other architectural attention, and and radiators. It remains compact enough to fi t a terrestrial architectural fi rm has taken a leading within the existing payload fairings of commercial role. In April, Skidmore, Owings & Merrill released its launch vehicles. concept for the “Moon Village,” which it is planning, Boeing followed in June at NASA’s Marshall designing and engineering in partnership with ESA Space Flight Center in Alabama. Its press release and the Massachusetts Institute of Technology. ★ noted that the concept “builds on the company’s experience from designing, building and operat- Contributors: Maria João Durão, Matthew A. ing the [International Space Station] for more than Simon, Daniel Inocente and Zachary Taylor

aerospaceamerica.aiaa.org | DECEMBER 2019 | 61 SPACE AND MISSILES

the receptacle will house two robotic external leak locator units, developed by the division in partnership with NASA’s Johnson Space Center in Texas. In August, Russia launched a fi nal experimental demonstration object research robot named Skybot F-850 to the ISS for testing, where it demonstrated interaction and tool exchange in collaboration with cosmonauts Aleksander Skvortsov and Alexey Ovchinin. In July, the India Space Research Organization launched the Chandrayaan-2 lunar exploration mission, which included the Vikram lander and the Pragyan lunar rover. The Pragyan rover was intended to travel up to 500 meters over one lunar Robots assisting astronauts, servicing day and would have collected data determining elemental abundance. However, in September, ISS and assembling the agency lost contact with Vikram as it attempt- BY ERIK KOMENDERA, JIAN-FENG SHI AND GARDELL GEFKE ed landing. NASA’s Mars Helicopter fl ight hardware com- The Space Automation and Robotics Technical Committee works to advance pleted fl ight testing in the 25-foot-wide (7.6 me- the development of automation and robotics technologies and their applications to space programs. ter) thermal vacuum chamber at NASA’s Jet Pro- pulsion Laboratory in California in January. It was Astronaut David Saint- n June, “Bumble Bee” became the fi rst of three attached to the Mars 2020 Rover in August for Jacques of the Canadian Astrobee robots to fl y under its own power in launch in July 2020. Space Agency watches space. The Astrobees are designed to operate In May, a power switching unit failure on the an Astrobee robot fl y inside the International Space Station using ISS caused several subsystem power outages and for the fi rst time inside I the International Space electric fans for propulsion and computer vision grounded a SpaceX resupply launch. A high-prior- Station. for navigation. The robots can be equipped with ity removal and replacement operation was con- NASA a small arm that allows them to grasp handrails or ducted in three days with the Canadian Dextre carry small items to perform tasks, such as inven- robot replacing the failed unit and restoring the tory, sensor surveys and mobile camera work. ISS to full power. In February, Canada announced Early this year, the Satellite Servicing Projects it would join NASA’s Artemis lunar Gateway pro- Division’s Restore-L, which will robotically in- gram with Canadarm 3, which will use artifi cial in- spect, refuel and relocate a satellite not designed telligence to operate autonomously. In August, the to be serviced, completed its spacecraft bus criti- Canadian Space Agency awarded Canada-based cal design review. In September, NASA awarded a MDA, the maker of the fi rst two Canadarms, Phase contract to Colorado-based Maxar Technologies A work for the Gateway external robotic interfaces to add an additional payload to Restore-L that will of the Deep Space Exploration Robotics program. demonstrate boom manufacturing and in-space In June, MDA delivered the European Space Agen- assembly of a fully functional communications cy’s Exo-Mars chassis and locomotion subsystem antenna with a robotic arm. In August, the divi- for the rover’s launching in 2020. By the end of July, sion’s Robotic Refueling Mission 3 completed an the MDA-built OSIRIS-REx Laser Altimeter instru- initial set of tool operations, bringing in-space ment had made 2 billion measurements on NASA’s refueling closer to reality. ISS’s Dextre robot op- mission to sample the near-Earth asteroid Bennu. erated and demonstrated the fi rst of three tools NASA’s Active Response Gravity Offl oad Sys- needed to transfer liquid methane from one tank tem was used for development and training for to another. The ability to transfer and store cryo- the ISS antimatter measurement payload, Alpha genic fl uid such as liquid methane in space could Magnetic Spectrometer or AMS-02, repair mis- help enable human travel to the moon, Mars and sion. The ARGOS robot simulated a microgravity beyond. Robotic Refueling Mission 3 launched to environment, allowing engineers and crew mem- the ISS in December 2018 and, after four months, bers wearing fully pressurized space suits to devel- demonstrated the longest zero boil-off storage of op and train for the complex repair procedure on liquid methane. In August, the Satellite Servicing a high-fi delity mockup of the AMS-02 payload. ★ Projects Division completed the development, build and delivery of the robotic tool stowage Contributors: Terry Fong, Robert Savely, Paul Valle, payload. When affi xed to the outside of the ISS, Stayne Hoff, Joseph Parrish and Brook Sullivan

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Supplying the space station, preparing Technologies a contract to build Gateway’s Power and Propulsion Element module. The PPE will to put humans back on the moon provide a high-power solar electric propulsion capability. In August, NASA formally announced BY HANG WOON LEE AND KOKI HO a request for proposals for logistics services to The Space Logistics Technical Committee fosters development of integrated Gateway, encouraging commercial partnerships space logistics capabilities that enable safe, affordable and routine space- in the cislunar regime with the total offering up to faring operations. $7 billion. In February and July, NASA announced the list orthrop Grumman and SpaceX completed of scientifi c payloads and experiments that will Commercial Resupply Services missions to fl y to the moon as part of the Commercial Lunar carry cargo to the International Space Station Payload Services program. CLPS is a major logis- Nthis year. Space X’s CRS 17 and 18 launched tics-based NASA initiative to deliver small-to-me- in May and July; Northrop Grumman’s Cygnus NG- dium payloads to the lunar surface as a service 11 launched in April. Phase 2 of NASA’s Commercial that NASA and perhaps others would buy as need- Resupply Services contract began with the launch of ed. NASA is using the same commercial approach Cygnus NG-12 to the ISS in November. SpaceX’s CRS to procure a human lunar lander system using a 19 was scheduled for December. public-private partnership — that is, buying a lo- In its efforts to establish a planned space sta- gistics service rather than owning and operating tion, China deorbited Tiangong-2 in July, marking the system. the offi cial end of its experimental space station On the academic side, in September, the Space mission. China is set for the launch of Tianhe for Systems Optimization Laboratory at the Univer- its modular space station. sity of Illinois at Urbana-Champaign (now moved NASA made a signifi cant movement in the to the Georgia Institute of Technology) completed ongoing development of the crewed lunar space- a one-year study for NASA to analyze the strategy The Power and fl ight program. In May, NASA Administrator Jim of deploying in-situ resource utilization systems Propulsion Element of NA SA’s lunar Gateway, in Bridenstine announced that the return-to-the- while considering the overall effi ciency of the an illustration, is planned moon program would be called Artemis, after space logistics architecture. The study introduced to be a high-power, the twin sister of Apollo. Artemis envisions the a new multifi delity space infrastructure optimi- 50-kilowatt solar electric use of the lunar Gateway to provide sustainable zation framework that can perform effi cient and propulsion spacecraft transportation to the lunar surface. Gateway, in a reliable system-level architecture trade studies. — three times more powerful than current near-rectilinear halo orbit, will be a transportation Also this year, researchers at the Massachusetts capabilities. and logistics hub for supporting future crewed Institute of Technology developed a new analysis NASA and cargo missions. In May, NASA awarded Maxar method called Mass, Crew time, and Risk-based Optimization of Sup- portability Strategies, or MCROSS, which enables forecasting and optimization of spares mass and maintenance crew time for a given level of risk, including options for in- space manufacturing. The development effort started in 2017 as part of a NASA Space Technolo- gy Research Fellowship in collaboration with NASA’s Langley Research Center in Virginia. MCROSS in- forms NASA technology investment and mission planning activities. ★

Contributors: Olivier de Weck, Andrew Owens and Robert Shishko

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International momentum for space of the Polar Resources Ice Mining Experiments, or PRIME-1. This was done in a simulated lunarlike resources ramps up cryogenic temperature and hard vacuum to integrate operations of TRIDENT, The Regolith and Ice Drill for BY LAURENT SIBILLE AND FORREST MEYEN Exploring New Terrain, with the Mass Spectrometer The Space Resources Technical Committee advocates affordable, Observing Lunar Operations for the lunar volatiles sustainable human space exploration using nonterrestrial natural prospector payload in the CLPS program. resources to supply propulsion, power, life-support consumables and Our knowledge of water on Mars increased in 2019 manufacturing materials. with new results published in March by two teams of NASA’s Mars Water Mapping Projects. The Subsurface Water Ice Mapping project at the Planetary Science Institute in Arizona produced a northern hemisphere map showing shallow ice deposits (within 0 to 5 meters of the subsurface) extending equatorward as far as 30 degrees north latitude in some places. Researchers at The MiniRASSOR JAXA, the Japan Aerospace Exploration Agency, and and the larger RASSOR 2.0, the University of Paris published the fi rst global map low-gravity excavators characterizing and mapping the surface geometry and designed for abundance of several hundred thousand hydrated educational outreach. mineral sites, dwarfi ng previous maps displaying on NASA the order of 1,000 sites. he international focus on space resources is The Mars Oxygen In-situ Resource Utilization shaping the return to surface exploration of the Experiment, or MOXIE, was installed in the Mars 2020 moon and future exploration of Mars. High-level rover in March for a launch window opening in July agreements of cooperation in space, including 2020. NASA’s Planetary Science and Technology from the utilization of space resources signed by Lux- Analog Research-funded robotic deep wireline drill, the Tembourg with Belgium in January and with the United Wireline Analysis Tool for Subsurface Observation of States in May followed by European Space Agency’s Northern Ice Sheets from Honeybee Robotics, reached Space Resources Strategy paved the way to agency-level the depth of 111 meters in Greenland equipped with agreements by Luxembourg Space Agency with NASA the Deep UV/Raman spectrometer developed by and ESA in October. The same month, Luxembourg NASA’s Jet Propulsion Laboratory. In August, the NASA Space Agency announced the establishment of a space ISRU Technology Project team completed many resource research center. critical hardware tests on scroll pumps, scroll dust This year also saw landing attempts on the lunar fi lter, electrolyzers with salts-contaminated water, surface, including the fi rst far-side landing, by China’s digging forces in compacted granular material and Chang’e-4 in January. Communications failures in fi nal including an integrated design study of a full-scale approach plagued the attempts by Israel’s Beresheet oxygen production mission using carbothermic in April and India’s Vikram in September that aimed reduction of lunar polar regolith. In May, NASA’s at being the fi rst to detect water ice in the subsurface. Kennedy Space Center’s Swamp Works completed In February, NASA’s Science Mission Directorate endurance performance tests of its low-gravity selected three small agency-provided payloads specifi c excavator RASSOR 2.0 and created MiniRASSOR, a to the detection of water ice in the lunar polar geologic miniature offspring in collaboration with a University context to be carried by the Commercial Lunar Payload of Central Florida student navigation team. Services program, or CLPS, under the Artemis program. Innovations in materials processing advanced The Near-Infrared Volatile Spectrometer System will in-situ construction technologies of landing pads, image surface and subsurface hydration and surface habitats and other long-term off-Earth structures. In composition of carbon dioxide and methane, and the May, NASA concluded the third phase of its 3D-printed Neutron Spectrometer System and the Advanced Neu- space habitat challenge. New York-based team AI tron Measurements at the Lunar Surface will measure SpaceFactory took home the $500,000 grand prize hydrogen abundance and bulk regolith composition. for its Martian habitat dubbed “Marsha.” Early in the Open University in August demonstrated water year, researchers at the University of Canterbury, New production by reacting Apollo soil samples with hy- Zealand, published the development of a magne- drogen in the ProSPA miniature laboratory for an ESA sia-silica binder system that can be produced from lunar resource prospecting payload to be carried by the Martian basaltic materials with similar properties to Roscosmos Luna-27 mission planned for 2025. Portland cement. Pacifi c International Space Center NASA’s Glenn Research Center in Cleveland and Hon- for Exploration Systems produced high-strength eybee Robotics of New York concluded tests in September defect-free basalt tiles with Hawaiian materials. ★

64 | DECEMBER 2019 | aerospaceamerica.aiaa.org SPACE AND MISSILES

Astronomers in April telescopes. The breakthrough was announced in a released the fi rst-ever image of a black hole. series of six papers published in a special issue of This one is 6.5 billion the Astrophysical Journal Letters. “We have taken times more massive than the fi rst picture of a black hole,” said Event Hori- the sun and is located at zon Telescope project director Sheperd S. Doele- the center of the galaxy man of the Center for Astrophysics Harvard & Messier 87. The image was made by an array of eight Smithsonian. “This is an extraordinary scientifi c ground-based instruments feat accomplished by a team of more than 200 re- called the Event Horizon searchers.” Telescope. In human spacefl ight, SpaceX in March Event Horizon Telescope Collaboration launched its Crew Dragon spacecraft on an uncrewed demonstration fl ight to prepare for its fi rst fl ight with a crew. The capsule’s docking at the International Space Station and splashdown in the Atlantic Ocean brought NASA a step closer to restoring the country’s ability to launch astronauts to and from the space station. “These are all capabilities that are leading to a day when we Space systems deliver progress toward are launching American astronauts on American rockets from American soil,” NASA Administra- space economy tor Jim Bridenstine said after the mission. The BY JOHN CARSTEN mission was a milestone in NASA’s Commercial Crew program in which contracts were awarded The Space Systems Technical Committee fosters the development, for Crew Dragon and Boeing’s CST-100 Starliner. application and operation of space systems, and addresses emerging issues in the area. NASA had hoped to certify the spacecraft for crew fl ights in 2017. he trend of reprogrammable communi- In the budding space tourism sector, Virgin cations satellites continued in 2019, with Galactic in August opened its Gateway to Space Boeing announcing in September that its building at the Spaceport America site in New T “software-defi ned” 702X geosynchronous Mexico. Earlier in the year, the company an- satellites will dynamically allocate bandwidth. nounced that it was ready to move its Eve carrier Turning to space science, China’s Chang’e-4 aircraft, the Virgin Space Ship Unity passenger lander and Yutu-2 rover spent the year explor- spacecraft, and supporting staff and equipment ing the area around their landing site on the far to the site in preparation for Virgin Galactic’s fi rst side of the moon. The rover and lander alternat- launch of space tourists. Virgin expects to begin ed between a dormant mode during the long lu- commercial operations in 2020. Also, Blue Origin nar nights and active mode during the days. The in January and May launched its New Shepard China National Space Administration, which vehicle from Texas without passengers in prepara- provided regular mission updates on its website, tion for its fi rst fl ight with people. reported in August that Yutu-2 had driven 271 me- In June, NASA announced that “private astro- ters. The January touchdown marked the fi rst soft nauts” would be permitted to fl y to the Interna- landing of a spacecraft on the lunar far side. Next, tional Space Station twice a year for short stays China plans to launch Chang’e-5, a lunar sample starting in 2020. The change in policy is part of return mission. NASA’s strategy to “stimulate a low Earth orbit In February, NASA announced the end of the economy.” Participants in these privately funded Mars rover Opportunity mission after receiving missions would have to ride on NASA-certifi ed no response from the rover since June 2018 when spacecraft, meaning the Crew Dragon or Starliner a dust storm temporarily enveloped the planet. once those are certifi ed by NASA. The dust probably crippled Opportunity by cov- The space station is not the only potential ering its solar cells and sensors. Opportunity trav- venue for those who want to visit space. Bigelow eled a total of 45.16 kilometers since its arrival in Aerospace of Las Vegas this year continued devel- 2004, NASA said. opment of its Genesis modules, infl atable space Researchers from the Event Horizon Telescope habitats to be launched aboard Vulcan rockets. project in April released the fi rst image of a black The startup Orion Span of California plans to hole, specifi cally one located 54 million light years build a luxury space hotel, Aurora Station, of- away in the center of the galaxy M87. The image fering guests 12 days of lodging in a pill-shaped was produced by an array of eight ground-based structure. ★

aerospaceamerica.aiaa.org | DECEMBER 2019 | 65 SPACE AND MISSILES

Space tethers to demonstrate propellantless propulsion, deorbiting satellites BY SVEN G. BILÉN

The Space Tethers Technical Committee focuses on the development and use of tether-based technology for space systems.

n June, a SpaceX Falcon 9 Heavy rocket launched into orbit the Tether Electrodynam- ic Propulsion CubeSat Experiment, a U.S. INaval Research Laboratory mission to investigate electrodynamic-tether propulsion. In orbit, TEPCE was to divide into two 1.5-unit cubesats connected by a 1-kilometer-long conducting tether. When current fl ows through the tether, it pushes against the Earth’s magnetic fi eld to generate drag thrust. TEPCE is instrumented to help understand tether deployment and dynamics and the surrounding plasma environment of its orbit. The E.T.PACK project, short for Electrodynamic Tether Technology for the Passive Consumable-less Deorbit Kit, kicked off in March with three years of funding from the European Commission. Led by The University of Deorbiting Spacecraft using Electrodynamic Teth- Universidad Carlos III de Madrid, E.T.PACK’s team Michigan’s Miniature ers payload for delivery to Texas-based NanoRacks includes six European institutions that will develop Tether Electrody- for launch from the International Space Station in over the next three years the fi rst proof-of-concept namics Experiment-1 2020. The payload comprises two 1U cubesats con- cubesat prepared low work-function tether, a novel type of electro- nected via a 100-meter-long conducting bare-tape for thermal vacuum dynamic tether with a specialized coating that en- tether. Once in orbit, the two cubesats will separate, testing. ables natural thermionic and photoelectric emis- University of Michigan/Twitter deploying the tether to determine its effectiveness as sion of electrons. The low work-function tether a deorbiting device. After observing the deployment promises fully passive electrodynamic deorbiting dynamics, a Spindt-array cathode will be enabled, technology. E.T.PACK’s overall goal is to develop a which will nominally result in system reentry within prototype deorbit kit and related software based on a few days. The entire mission duration is expected to the tether technology. be less than six months. In August, Virginia-based TriSept Corp., Cal- In July, the University of Michigan completed ifornia-based Rocket Lab and California-based fabrication of the Miniature Tether Electrodynam- Millennium Space Systems announced Dragracer, ics Experiment-1, or MiTEE-1, 3U cubesat and com- a mission to demonstrate electrodynamic-tether pleted vibration testing after environmental screen- technology to deorbit satellites. Once in orbit, Dra- ing. MiTEE-1 is expected to fl y on Virgin Orbit’s gracer will split into two satellites, with one unfurl- Launcher One’s second fl ight in early 2020 as part of ing Tethers Unlimited’s Terminator Tape, a con- NASA’s Educational Launch of Nanosatellites pro- ductive tether designed to produce drag to lower gram. For this fi rst mission, MiTEE-1 was to use no the satellite’s orbit. The other will reenter normally. tether but instead a deployable, rigid, 1-meter boom Hence, Dragracer will be able to compare how the to measure the electrodynamics of electron current electrodynamic tether increases drag and shortens collection to a pico-/femto-scale satellite endbody on-orbit lifetime. It is predicted the satellite with the (satellite mass up to 200 grams) in the Earth’s iono- tether will reenter Earth’s atmosphere in two to four sphere using a 200-volt variable bias power supply. weeks, whereas the other satellite without a tether The cubesat also uses an electron beam fi lament will remain in orbit for eight months to a year. source to emit electrons in to the ionosphere that At the beginning of October, a team led by York is characterized by a miniature Langmuir probe in- University in Toronto was on track to fi nalize its strument.★

66 | DECEMBER 2019 | aerospaceamerica.aiaa.org SPACE AND MISSILES

Blue Origin’s New Shepard booster lands after its 11th ﬂ ight in May. Blue Origin

Origin revealed its Blue Moon lander and BE-7 engine in May; it foresees its initial fl ight in 2023. Blue Origin broke ground in Huntsville, Alabama, in January, on its factory to build BE-4 engines, which will be used for its New Glenn and UL A’s Vulcan Centaur launchers. NASA’s Orion crew capsule, essential for the Private space companies strive for Artemis program, performed a fl ight test of its ascent abort motor in July. The engine section of crewed fl ights, lunar exploration NASA’s Space Launch System was completed in August in preparation for its “green run” test, in BY DALE ARNEY which the integrated core stage will test fi re its en- The Space Transportation Technical Committee works to foster continuous gines at NASA’s Stennis Space Center in Mississip- improvements to civil, commercial and military launch vehicles. pi, planned for 2020. SpaceX and Northrop Grumman Innovation paceX continued to advance reusability of Systems continued to deliver cargo to the Inter- the Falcon 9 launcher this year. In November, national Space Station as part of the Commercial the company achieved the fourth launch Resupply Services contract. Sierra Nevada Corp. Sand recovery of the same Falcon 9 fi rst stage. completed the fi nal design review for its Dream The stage powered the Falcon 9 that delivered 60 Chaser spacecraft, on track to launch cargo to the Starlink satellites to orbit. The rocket’s payload ISS in 2021 on UL A’s Vulcan Centaur. In March, fairing was fl own previously on a Falcon Heavy SpaceX completed its fi rst demonstration mis- launch. Also, the company’s Dragon spacecraft sion to send crew to the ISS by launching an un- returned from a third mission to the International crewed Crew Dragon to autonomously dock with Space Station in August. SpaceX also captured two the ISS and then return to Earth. Boeing’s Starliner fairing halves from launches in June and August. crew vehicle performed parachute tests in July in After its inaugural demonstration fl ight in Febru- preparation for its planned demonstration mis- ary 2018, Falcon Heavy commenced commercial sion in late 2019. launches in April with the delivery of a communi- In August, an Ariane 5 fl ew the design’s 105th cations satellite to geosynchronous orbit. Through- mission after eclipsing 100 launches in late 2018. out the year, SpaceX continued development on its China landed the Chang’e-4 lander and rover next-generation launcher, Starship, in Texas and on the far side of the moon in January. In the fi rst Florida in preparation for demonstration fl ights in privately funded mission of its kind, SpaceIL of late 2019 or 2020. Starhopper, the test platform for Israel delivered the Beresheet robotic lunar land- Starship, completed a 150-meter test fl ight in Au- er to lunar orbit in April before its failed landing gust at the SpaceX South Texas Launch Site. attempt. The Indian Space Research Organization United Launch Alliance this year launched delivered the Chandrayaan 2 orbiter to lunar or- Atlas V, Delta IV Heavy and the fi nal Delta IV Me- bit in August before losing contact with the Vikram dium rockets. The Atlas V launch in August was lander during its September landing attempt. UL A’s 135th consecutive. UL A’s next-generation Also in August, the U.S. Air Force’s X-37B reus- launcher, Vulcan Centaur, completed its fi nal de- able spaceplane broke its previous fl ight record of sign review in May, and the company converted its 719 days in orbit. Alabama factory to produce the vehicle in prepa- After starting commercial operations in late ration for its planned debut in 2021. 2018, Rocket Lab launched Electron rockets four Blue Origin fl ew the New Shepard suborbital times this year with hopes for more launches be- vehicle for the 11th time in May in preparation fore the end of the year. In February, Virgin Ga- for its fi rst crewed fl ight in late 2019 or 2020. Blue lactic launched the fi rst passenger in the Virgin Origin expanded its manufacturing facilities near Space Ship Unity, its suborbital launcher for tour- Kennedy Space Center in Florida to prepare for ism, after the Unity launched above 80 kilometers New Glenn, the company’s orbital launcher. Blue in December 2018. ★

aerospaceamerica.aiaa.org | DECEMBER 2019 | 67 SPACE AND MISSILES

U.S. military awards contracts is part of Long Range Precision Fires, one of the Army’s priorities handled under cross-functional for wide-ranging hypersonics projects teams. The six cross-functional teams fall under the new U.S. Futures Command, which was stood BY JAMES D. WALKER AND NICHOLAS J. MUESCHKE up in Austin, Texas, last year. The Weapon System Effectiveness Technical Committee advances Also in August, Lockheed was selected for a the science and technology of predicting, measuring, evaluating and $347 million contract to integrate at least eight of improving the lethality of weapon systems. these glide bodies into a battery of Long Range Hypersonic Weapon launchers. Subcontractors to ultiple U.S. government-led boost-glide Lockheed Martin are Dynetics, Integration Innova- and air-breathing prototype-develop- tion Inc. (i3), Verity Integrated Systems, Martinez ment efforts continue to progress in & Turek, and Penta Research. The Air Force also the realm of hypersonics, defined as has two ongoing hypersonics boost-glide weapons fl ight above Mach 5. The Conventional programs: Advanced Rapid Response Weapon and MPrompt Strike program is moving the prototype Hypersonic Conventional Strike Weapon. DARPA Common-Hypersonic Glide Body, or C-HGB, from and the Air Force are also funding the Tactical Boost Sandia National Laboratories to commercial pro- Glide and Hypersonic Air Breathing Weapon Concept duction. Specifi cally, in August, Dynetics Technical programs. In support of these major programmatic Sequence of high- Solutions, based in Alabama, with subcontractors efforts, progress continued on multiple other research, speed video frames from General Atomics Electromagnetic Systems, Lock- a Mach 14.8 conical fl ight engineering and policy initiatives. These include heed Martin and Raytheon, was awarded a $351.6 body launched from a programs looking to expand the national testing million program to produce 20 C-HGB prototypes two-stage light gas gun infrastructure, grow the hypersonics engineering for the U.S. Army, Navy and Missile Defense Agency. into a controlled, rarefi ed talent pipeline, and increase the development and atmosphere, looking at These glide bodies are intended mainly for the signature of the vehi- manufacturing capacity of advanced materials that testing, but the Army’s goal is to deliver a residual cle and wake. can handle extreme conditions. combat capability to soldiers by 2023. This effort Southwest Research Institute On the defensive side, there are ongoing programs related to defeating these maneuverable bodies. Last year MDA put out a solicitation and funded 21 $1 million studies for defense. In August and Sep- tember, fi ve of these were selected for more work, all with roughly $4.5 million in additional funding, namely to Boeing for Hypervelocity Interceptor Concept for Hypersonic Weapons, Lockheed Mar- tin for Valkyrie Interceptor Terminal Hypersonic Defense, Lockheed Martin for Hypersonic Weap- ons System Defense Concept-Dart, Raytheon for Non-Kinetic Concept for Hypersonic Defense and Raytheon for SM-3 Hawk. Along with these awards, there is much discussion about a space-based sensor layer for missile defense. The ability to observe and track a hypersonic vehicle in fl ight is essential due to the missiles’ maneuverability within the atmosphere. Missile defense is progressing in other areas. March saw the fi rst salvo test of the Ground-based Midcourse Defense segment: two ground-based interceptors, or GBI, were launched from Vandenberg Air Force Base in California in response to the launch of the complex intercontinental ballistic missile target from the test site on Kwajalein Atoll. The lead GBI of the two-missile salvo intercepted and destroyed the target reentry vehicle. The second, trailing GBI examined the resulting debris and remaining objects. Not fi nding any other reentry vehicles, the trailing GBI selected the next most lethal object and struck it. There were also continued fl ight intercept tests by both the THAAD and Arrow systems. ★

68 | DECEMBER 2019 | aerospaceamerica.aiaa.org INTEGRATION

not be able to fl y in much of the U.S. airspace at the beginning of 2020. Meanwhile, FAA evaluated two aircraft surveillance technologies that would allow aircraft to safely fl y in closer proximity over oceans. Based on its evaluation, FAA committed to using one in the near term and to continue to study another for future use. Specifi cally, in April, FAA committed to implement by 2022 new international standards that allow reduced distances between aircraft, called minimum separation standards. These reduced distances would be enabled by a surveillance technology known as enhanced ADS-Contract. In contrast, FAA determined that the costs of using space-based ADS-B in U.S. oceanic airspace substantially outweigh the effi ciency benefi ts. The popularity of small unmanned aerial sys- 737 MAX grounding and ADS-B lead tems, or drones, for commercial and local govern- eventful year ment use again challenged air navigation service providers to develop rules and procedures that BY FRANK L. FRISBIE balance safety against the utility of these myriad The Aerospace Traffi c Management Integration Committee monitors, applications. With the support of NASA, the FAA evaluates, and seeks to infl uence the direction of ATM technologies with a is moving forward incrementally to allow drones focus on effi ciency, public safety and national security. greater access to U.S. airspace, including fl ights over people and fl ights beyond line of sight. Giv- In July, Amazon ortions of the FAA were closed in January ing credence to the future drone role in package Prime Air fi led a detailed as a continuation of the government shut- delivery, Amazon Prime Air fi led a detailed peti- petition to FAA for down that began in December 2018. While tion to FAA in July for permission to operate under permission to operate the loss of those affected FAA services other an air carrier operating certifi cate while in Octo- its delivery drone under P an air carrier operating than air traffi c control was temporary, the uncer- ber, UPS Flight Forward received FAA certifi ca- certifi cate. tainty surrounding the events had such a destabi- tion to operate a drone airline. In Europe, Swiss Amazon lizing effect on staff and aviation stakeholders that ANSP Skyguide announced in August deployment Congress enacted a two-year funding appropria- of the Swiss U-space fl ight information system tion to stabilize operations. for drones. The crash of a Boeing 737 MAX commercial In September, American Airlines retired its MD- airliner in March, following an earlier 737 MAX 80 aircraft, and Airbus announced that it would crash in October 2018, resulted in the grounding stop production of the A380 after meeting current of approximately 400 of the aircraft being fl own by orders to Emirates Airlines through 2021, even airlines around the world. FAA issued an “Emer- while All Nippon Airways was introducing nonstop gency Order of Prohibition” applying to Model A380 service from Nikita and Honolulu. Boeing 737-8 and 737-9 (the 737 MAX) in March. These test-fl ew its autonomous electric passenger air events precipitated intense scrutiny of the aircraft vehicle prototype but it crashed in June in subse- systems, instructional materials, pilot training quent testing, setting the program back. and communications among the parties involved, Motivated by a presidential mandate to free including FAA, Boeing and 737 MAX operators. portions of spectrum for nongovernment use, a Perhaps most signifi cantly, critics (e.g., the U.S. cross-agency team of the FAA, the Defense and Offi ce of Special Counsel) focused attention on Homeland Security departments, and NOAA are the certifi cation methodology and the interac- engaged in the Spectrum Effi cient National Sur- tion between the FAA oversight and the manufac- veillance Radar program, which would allow 30 turer. The scrutiny continued into the last months megahertz of frequency spectrum below 3 GHz of the year with the fl eet still grounded. (1,300 to 1350 MHz) to be released. In August, the The mandate of equipping of aircraft with Au- FAA updated industry on the program, including tomatic Dependent Surveillance-Broadcast Out consolidation of required service volumes that surveillance by Jan. 1, 2020, resulted in substantial removed many terminal air traffi c control surveil- compliance, but about 25,000 of 106,000 General lance services from the original program goals. ★ Aviation aircraft were still unequipped at the end of November . Without ADS-B Out, an aircraft would Contributor: Charles Keegan

aerospaceamerica.aiaa.org | DECEMBER 2019 | 69 INTEGRATION

Progress toward the 2030 vision of CFD or LAVA, team at Ames refactored its LAVA Cartesian framework to better exploit these new architectures. BY REYNALDO J. GOMEZ III, ANDREW W. CARY AND MUJEEB R. MALIK In collaboration with the Orion Multi-Purpose Crew Vehicle loads and dynamics team at NASA’s Johnson The CFD Vision 2030 Integration Committee advocates for, inspires and Space Center in Houston, the LAVA team demonstrated enables community activities recommended by the vision study for in June the power of this approach by producing the revolutionary advances in the state-of-the-art of computational technologies most detailed turbulence-resolving simulations yet needed for analysis, design and certifi cation of future aerospace systems. of various abort scenarios. Leveraging the same Cartesian adaptive mesh refi nement infrastructure used in the Orion simulations, the LAVA team implemented the Lattice-Boltzmann method, or LBM, which promises to be an order of magnitude faster than traditional approaches on the same mesh, to simulate vehicles in unsteady subsonic fl ows. The team demonstrated in August that LBM can accurately predict the acoustics of a small but complex quadcopter drone in forward fl ight with a one-week A NASA team’s scale-resolving simula- turnaround time and no manual mesh generation tion of the Orion Multi- effort. Coupling LBM with far-fi eld noise propagation Purpose Crew Vehicle software enables capturing tonal noise and showed during an ascent abort good agreement in broadband noise trends when scenario at transonic compared to wind tunnel microphone data. speed and high angle of attack in support of NA- CFD computations by researchers at Ames and SA’s Ascent Abort Test-2 NASA’s Langley Research Center in Virginia showed in July. The image shows that nonlinear turbulence modeling (such as with a snapshot of pressure quadratic constitutive relations or a full Reynolds (black is low, white is stress model) is necessary to predict the size of the high) on a slice through two of the abort motor separation bubble in the juncture fl ow experiment nozzles. conducted in Langley’s 14-by-22-foot Subsonic NASA Tunnel. Areas of disagreement, particularly in the ignifi cant developments continued this year prediction of Reynolds stresses remain, necessitating toward achieving the goals defi ned in NASA’s additional research in turbulence modeling. CFD Vision 2030 study released in 2014. At AIAA’s Aviation Forum in June, NASA’s Aero- Academia made progress on algorithms and nautics Research Mission Directorate announced solvers for both second-order and higher- the selection of a new technical challenge for its Sorder methods. While second-order codes continue Revolutionary Computational Aerosciences effort to to dominate industrial applications, higher-order “develop and demonstrate computationally effi cient solvers are beginning to show their promise. Testing, eddy-resolving modeling tools that predict maxi- conducted at United Technologies Research Center in mum lift for transport aircraft with same accuracy February, of the high-order discontinuous-Galerkin as certifi cation fl ight tests.” A signifi cant fraction of solver eddy, developed at NASA’s Ames Research the certifi cation fl ight testing is done in the high-lift Center in California, has demonstrated that it is area of the fl ight envelope and use of accurate CFD an order of magnitude faster for the same level of tools could save hundreds of millions of dollars in accuracy on canonical benchmarks than existing new aircraft development programs by reducing production solvers. This demonstrates the potential flight-test requirements as well as reduce testing for emerging high-order scale-resolving methods to risk by improving the prefl ight characterization of impact the design and analysis of turbomachinery the aircraft behavior. A collaborative Boeing-NASA components. Development continues in the area of high-lift test on Common Research Model began in automated high-order mesh generation to enable October in the QinetiQ tunnel in the United Kingdom effi cient use of h-p refi nement, varying the local mesh to provide experimental data to allow validation of CFD size (h) and polynomial degree (p). tools for this important area of the fl ight envelope. At The CFD 2030 vision study emphasized the im- a NASA review in September, a Stanford University portance of developing algorithms better-suited to team showed wall-modeled large-eddy simulation the many core computing architectures of tomorrow results for the Japan Aerospace Exploration Agency, toward achieving the time-and-space resolution or JAXA, standard model in good agreement with goals for scale-resolving simulation. Earlier this experiment for maximum lift, showing the promise year the Launch Ascent and Vehicle Aerodynamics, for such cost-effi cient scale resolving methods. ★

70 | DECEMBER 2019 | aerospaceamerica.aiaa.org INTEGRATION

Hybrid electric concepts move toward On the light aircraft front, Canada-based Har- bour Air announced in March a partnership with demonstration magniX, a research and development company based in Seattle that is developing high power BY MICHAEL IKEDA, GOKCIN CINAR AND JOHN NAIRUS density electric motors, to convert a de Havil- The Energy Optimized Aircraft Systems Integration Committee works to land DHC-2 Beaver to a battery electric drive- promote a better understanding of energy optimized aircraft and equipment train. Prototype testing was planned for Novem- systems, from concept development to vehicle production, including ber with commercial fl ight certifi cation targeted relevant international academic and industrial experience. for 2021. In June, Los Angeles-based Ampaire demonstrated its parallel hybrid electric power- he push toward hybrid electric solutions train on a converted Cessna 337 Skymaster. The for aircraft propulsion, power and thermal Cessna’s rear engine was replaced with Ampaire’s management continued with a focus on the battery-powered 180-kilowatt electric motor to T need for hardware demonstrators. In April, provide two independent sources of power, one Collins Aerospace unveiled a $50 million invest- fully electric and one traditional. Ampaire ex- ment to add 2,300 square meters of lab space to pects the aircraft to be certifi ed by 2021. NASA test advanced electric power systems. “The Grid” also continued to progress its X-57 program with is intended to be fully operational in 2021 and will the August start of load testing of its high aspect support the design and testing of a 1-megawatt ratio wing. Meanwhile, Zunum struggled to raise motor, motor controller and battery system. Series B funding and shut down its Bothell, Wash- Looking toward the regional jet market, ington, headquarters in July and laid off the ma- Rolls-Royce announced in August that it began jority of its employees. ground tests of the 2.5-MW E-Fan X generator. While demonstrations of existing technolo- At the Paris Air Show in June, United Technol- gies have been a focus, NASA announced $6 mil- ogies Advanced Projects announced Project lion in funding over three years for the Center 804, focused on flying a modified Bombardier for Cryogenic High-Efficiency Electrical Tech- Dash 8-100 hybrid-electric turboprop within nologies for Aircraft at the University of Illinois three years targeted at 30% fuel savings. UTAP at Urbana-Champaign. The center will pursue a A concept of an advanced commercial is replacing one of the turboprops with a par- fully electric aircraft centered on cryogenic liq- transport aircraft from allel hybrid powertrain consisting of a 1-MW uid hydrogen and fuel cells. the Center for Cryogenic engine optimized for cruise efficiency and a The NASA-funded University Led Initiative High-E ciency Electrical battery-powered 1-MW electric motor designed Electric Propulsion — Challenges and Oppor- Technologies for Aircraft, for takeoff and climb assist. Also at the Paris Air tunities project being carried out by Ohio State which received funding from NASA to research Show, Rolls-Royce announced its intent to ac- University, Georgia Tech, University of Wiscon- all-electric aircraft. quire Siemens’ eAircraft business, and on Oct. 1 sin-Madison, University of Maryland and North University of Illinois it announced the acquisition was complete . Carolina A&T State University completed its second year of research and hardware development. This fi ve- year project includes extensive testing and data characterization of commercially available battery cells, testing of a 200-kW integrated electric machine, power electronics and thermal management system, and system level aircraft assessment that integrates test data from actual hardware development, including integrated battery, thermal management system and propulsion models. ★

aerospaceamerica.aiaa.org | DECEMBER 2019 | 71 INTEGRATION

Space exploration focuses on asteroids core samples for analysis; Brian May of the rock BY LEENA SINGH, SURENDRA P. SHARMA AND CHRISTOPHER MOORE band Queen processed the images to produce ste- reoscopic views of asteroid Ryugu. The Space Exploration Integration Committee brings together experts on Seven years after landing on Mars, NASA’s Jet topics relevant to future human and robotic exploration missions. Propulsion Lab’s Curiosity rover continued to collect and telemeter new discoveries. In August, NASA reported that the rover had drilled its 22nd soil sample from the Martian surface inside the Gale crater. Curiosity has been heading to locations where overhead imagery from Mars Recon- naissance Orbiter detects areas of interest, and its in-situ fi ndings have sometimes differed from the orbiter’s aerial indications, including that water-formed clay proliferates in certain areas of the Gale crater. Throughout 2019, NASA rolled out its Arte- mis lunar exploration program, geared toward a crewed lunar landing by 2024 to explore more of Earth’s moon and establish sustainable exploration assets, thus preparing for longer-range crewed Mars missions. Toward Artemis, NASA has been focusing efforts on its heavy-lift Space Launch System, the Orion spacecraft and the lunar Gateway to orbit the moon as its backbone for deep-space exploration. To that end, in August, NASA and Boeing completed functional tests on the SLS rocket engine section and in September completed its integration with the core rocket body. Final assembly of the core stage was expected in December. The team also commenced con- This picture of the n June, OSIRIS-REx, NASA’s asteroid sample re- necting the RS-25 engines to the main propulsion boulder-covered surface turn spacecraft, descended to a 1.1-kilometer systems within the engine. of the asteroid Bennu orbit (about 680 meters altitude) around the as- The European Space Agency and NASA arrived was taken by a camera teroid Bennu. The low orbit made OSIRIS-REx, at a consensus on Gateway’s orbit, determining on NA SA’s OSIRIS-REx I spacecraft in April. short for the Origins, Spectral Interpretation, that it will follow a near-rectilinear halo orbit, a NASA Resource Identifi cation, Security-Regolith Ex- highly elliptic lunar orbit ranging from 3,000 km plorer, the closest orbiter of a celestial object ever from the lunar center to about 70,000 km. NRHO and Bennu the smallest object ever orbited by a is attractive because its relatively stable equi- spacecraft. Bennu’s extremely low microgravity librium allows nearly continuous line of sight to means that at even just 680 meters, OSIRIS-REX both Earth and the far side of the moon, allowing is in a 62-hour orbit. The spacecraft entered low- spacecraft parked in NRHO to serve as a com- altitude orbit around Bennu in December 2018 munications hub between landers and ground after a fi ve-month series of survey and remote im- control. Gateway will serve as a permanent stag- aging operations after fi rst visual contact. A staged ing post for transit between Earth and the moon approach sequence transferred it from its safe, 50- and, once commissioned, will save signifi cant fuel km distant hold point to its proximal survey orbit. to ferry people or resources between Earth, the Toward its exploration endeavors, NASA spent moon and beyond. much of 2019 focused on site selection for surface In July, the Indian Space Research Organiza- touchdown on Bennu later in the program as part tion launched its second lunar mission, which of its sample-retrieval objective. It has identifi ed entered lunar orbit in August, initiating its land- four candidate sites from which a primary and a er’s descent in September. Survey orbiter Chan- backup landing site were to be selected based on drayaan-2 is equipped with a suite of instruments safety, accessibility and scientifi c merit. including high-resolution cameras to precisely JAXA, the Japan Aerospace Exploration Agen- map the lunar surface that will survey Earth’s cy, conducted two landing descents of its asteroid moon from polar orbit passes for a year. Its lander, sample-return spacecraft, Hayabusa2, in Febru- Vikram, made a hard descent to the lunar south ary and July, collecting imagery and surface and pole, losing ground contact thereafter. ★

72 | DECEMBER 2019 | aerospaceamerica.aiaa.org INTEGRATION

Beta Technologies ﬂ ew its prototype experimental tilt-rotor electric vertical takeo and landing aircraft at Plattsburgh International Airport in New York. Eric Adams

Also in May, Alaka’I Technol- ogies of Massachusetts revealed a full-scale replica of a fi ve-passenger, hydrogen fuel-cell-powered multicopter with a projected endurance of up to four hours. As of the end of September, Alaka’I was working with the FAA to establish a certifi cation basis for the aircraft; it report- Flight testing begins for new urban air edly began testing a fl ying prototype in May. The past year also saw developments important mobility, electric propulsion aircraft to the technical realization and societal integration BY KENNETH H. GOODRICH of on-demand air mobility. In January, Georgia Tech’s Center for Urban and Regional Air Mobility The Transformational Flight Integration Committee serves as a focal point for hosted its launch event, bringing 100 academics, a community of practice engaged in technical, business and societal issues entrepreneurs and policymakers to Atlanta for a associated with transformational approaches to on-demand air mobility enabled by the convergence of advanced technologies. daylong conference to envision the specifi c local and state opportunities and challenges related to he pace of on-demand air mobility contin- on-demand air mobility. ued to accelerate during 2019 with multiple In March, the Go Fly Prize awarded fi ve teams companies revealing new aircraft develop- $50,000 each in Phase II prizes. The Go Fly Prize T ment programs and conducting initial fl ights is an international, two-year, $2 million competi- of full-scale vehicles. tion to foster the realization of safe personal ver- In January, Beta Technologies of Vermont tical fl ight. The Phase II awards were made based fl ight-tested a piloted, experimental tilt-rotor on quality of design and progress toward fl ight electric vertical takeoff and landing aircraft at demonstration scheduled for February 2020. Plattsburgh International Airport in New York. Vid- In July, the European Union Aviation Safe- eos showed the aircraft fl ying in challenging winter ty Agency published “Special Condition for weather. Also in January, Bell exhibited a full-scale Small-Category Vertical Take-Off and Landing replica of its Nexus aircraft, a tilt-duct eVTOL con- (VTOL) Aircraft.” While reducing regulatory uncer- fi guration, at the Consumer Electronics Show in tainty, the special conditions established relatively Las Vegas. The Nexus has four dedicated passenger challenging requirements for these novel vehicles. seats and a fi fth seat for a pilot until self-piloting For example, for VTOL aircraft intended to oper- vehicle technology has been matured and certifi ed. ate over densely populated areas or intended for Boeing’s Aurora Flight Sciences conducted the fi rst commercial passenger service, system design as- fl ight of its full-scale, two-passenger Passenger Air surance levels are more similar to transport aircraft Vehicle in January at its Virginia facility. After four than small airplanes or helicopters. test fl ights, the prototype was damaged in a crash In October, NASA released a solicitation for following an in-fl ight failure of one of its six lift fans. its fi rst Urban Air Mobility Grand Challenge and In May, Lilium Aircraft of Germany complet- GC-Developmental Testing. The goal of these ed the fi rst fl ight of its fi ve-seat, all-electric duct- events is to improve urban air mobility safety and ed-fan eVTOL aircraft. Flown as an unmanned air- accelerate scalability through integrated demon- craft, the prototype demonstrated takeoff, hovering strations of candidate operational concepts and and landing. Airbus Helicopters conducted a fi rst, scenarios. The solicitation seeks the participation unmanned, tethered test fl ight of its four-seat City of aircraft developers and airspace service suppli- Airbus multicopter aircraft in May in Germany. ers to participate in the challenge. ★

aerospaceamerica.aiaa.org | DECEMBER 2019 | 73 AEROSPACE OUTREACH

50 years after Apollo 11, the world Aviation and aerospace museums in the Unit- ed States embarked on a series of new educa- took note tional programs and immersive learning exhibits and held recognition events for living legends. BY BEN SARAO Throughout May and June, the National Museum The History Committee works to preserve the record of aerospace advances of the U.S. Air Force in Dayton, Ohio, commemo- and recognize their impacts on modern society. rated the 75th anniversary of D-Day. Visitors could experience the reality of the D-Day airborne in- he major history event of 2019 was the 50th vasion using HistoPad, an immersive, interactive anniversary of the Apollo 11 lunar landing augmented-reality tablet. mission. On July 20, 1969, the fi rst crewed France awarded the Legion of Honor medal to T lunar landing was televised, and nearly 600 three World War II veterans from Washington state million people watched worldwide. The legacy of at the Museum of Flight in Seattle in May. Dan- Apollo 11 was revisited this year in several new iel F. McAllister, a former P-38 aircraft mechanic; documentary fi lms. PBS aired a three-part series, Stanley L. Zemo, a former demolition squad lead- “Chasing the Moon,” a six-hour program higher; and Richard A. Nelms, a former B-17 pilot, re- lighting the steps taken by the United States to ac- ceived the medals. complish the fi rst crewed lunar mission and sub- Notable international historical aerospace sequent ones to explore the surface of the moon. events included the China National Space Ad- This fi lm included never-before-broadcast mate- ministration’s Chang’e-4 lunar lander with rover rial found in archives or donated from personal landing on the far side of the moon in January for collections of several astronauts. a three-month mission. The scientifi c payload of CNN aired “Apollo 11,” which included fi lm the Chang’e-4 lander was powered by a radioiso- segments that had been stowed away in govern- tope thermoelectric generator. The lunar rover ment archives for nearly half a century. The fi lm was equipped with a solar panel to power the ve- is mostly made of newly discovered 70-mm foot- hicle during the lunar day. The rover was able to age that includes intimate personal moments of transmit data back to Earth, despite the lack of

Neil Armstrong suits the Apollo 11 astronauts being suited up prior to radio frequencies on the far side, via a dedicated up on the morning he the launch on July 16, 1969; a segment of astro- satellite sent earlier to orbit the moon. The lunar and fellow astronauts naut Neil Armstrong stepping down on the lunar landing and subsequent rover relay via satellite Buzz Aldrin and Michael surface made by astronaut Buzz Aldrin from the data transmission are considered a landmark Collins were launched on doorway of the Lunar Excursion Module; and se- achievement for space exploration. a Saturn V rocket toward the moon. lect sound bites from 11,000 hours of NASA audio In April, JAXA, the Japan Aerospace Explo- NASA ﬁ les from the mission. ration Agency, separated the small carry-on impactor that had been on the asteroid explorer Hayabusa2 for deployment to Ryugu and put the impactor into operation creating a crater on the surface. In July, India launched Chan- drayaan-2, which has a 3,500-kilogram mass, carries 13 payloads and has three elements — lunar orbiter, lander and rover — all developed by ISRO, short for the Indian Space Research Organization. India is the fourth country to attempt a soft lunar landing on the moon. On Sept. 7, ISRO reported that it had lost contact with the lander. NASA’s Lunar Reconnaissance Or- biter made recon passes of possible lander sites on Sept. 17 and Oct. 14 but couldn’t ﬁ nd the lander. ISRO reported that the other payloads still aboard the Chandrayaan-2 lunar orbiter, including the Imaging Infrared Spectrome- ter, are performing well. ★

74 | DECEMBER 2019 | aerospaceamerica.aiaa.org AEROSPACE OUTREACH

Apollo anniversary inspires more and international partners to establish sustainable exploration by 2028. Success in missions such as exploration and milestones Artemis would allow for future crewed missions to Mars. BY AMIR S. GOHARDANI Meanwhile, progress was made this year on the The Society and Aerospace Technology Outreach Committee promotes Mars 2020 rover, an important deep-space mission the transfer and use of aerospace technology for the benefit of society. whose launch window is scheduled to open in July 2020. The rover is part of a long-term effort of robotic exploration of the red planet, and NASA’s Jet his year saw important milestones and Propulsion Laboratory in California announced in aerospace endeavors, and among the most October that for the fi rst time the vehicle had carried inspiring events were those celebrating the its full weight on its legs and wheels. 50th anniversary of Apollo 11’s historic This year also recorded one of the busiest days moon landing. The mission that put humans in aviation history. According to Flightradar24, a Ton the lunar surface for the fi rst time undoubtedly real-time, air-traffi c tracking service, 230,408 fl ights inspired thousands of engineers and scientists over took to the skies on July 24. Excluding certain sen- the years and may have helped revive our quest to sitive air traffi c, such as military fl ights, this fi gure explore our solar system. represented nearly every trackable aircraft in the Commander Neil Armstrong and lunar module world, including private jets, gliders, sightseeing pilot Buzz Aldrin formed the American crew that fl ights, helicopters, personal aircraft, commercial landed the Apollo Lunar Module Eagle on July 20, passenger flights and cargo planes. To put the 1969, and on July 20, 2019, NASA and Vice President number in perspective, the greatest number of Mike Pence marked the anniversary by restating fl ights recorded in 2017 was 190,003 on Aug. 24. the White House’s plan to return humans to the NASA astronauts Each year’s low typically occurs on Dec. 25; 101,511 moon by 2024. Christina Koch, left, and fl ights were recorded on Christmas Day in 2017. While the primary goal of NASA’s new program, Jessica Meir check the In the quest for further space exploration, artifi cial fi t of a spacesuit as they dubbed Artemis, is to land the fi rst woman and intelligence identifi ed two new “Super-Earths” in May. prepare for the fi rst-ever next man on the lunar surface by 2024, a secondary all-female spacewalk. The machine-learning algorithm called AstroNet-K2, objective for NASA is to collaborate with commercial NASA a neural network modifi ed to hunt through data from NASA’s Kepler space telescope, spotted the two planets, named K2-293b and K2-294b. Implementing the deep-learning algorithm capable of separating real exoplanet signals from false positives, K2-293b is about 2.5 times as big around as Earth, while K2-294b is 1.7 times as big around. These planets orbit a star about 1,300 and 1,200 light-years away, respectively. In October, two astronauts carried out the first all-female spacewalk. After postponing an earlier all- female walk in March due to unavailability of spacesuits that fit both female astronauts, NASA made history by sending Christina Koch and Jessica Meir outside the International Space Station to replace a power controller. The walk lasted seven hours and 17 minutes. ★

aerospaceamerica.aiaa.org | DECEMBER 2019 | 75 23rd AIAA International Space Planes and Hypersonic Systems and Technologies Conference 10-12 MARCH 2020 | MONTRÉAL, QUÉBEC, CANADA

NEW EARLIER DATE!

Hosted by the Canadian Aeronautics and Space Institute (CASI), the 23rd AIAA International Space Planes and Hypersonic Systems and Technologies Conference provides a forum for discussion and exchange of information for attendees from across the globe about leading-edge research and development activities associated with space planes and hypersonic atmospheric flight vehicles and the technologies underpinning these capabilities. Presentations will be provided on national programs from North America, South America, Australia, Europe, and Asia and multiple opportunities for international collaboration will be discussed.

Technical sessions will include the following topic areas:

› Missions and Vehicles › Guidance and Control Systems

› Operational Systems Aspects › Materials and Structures for Vehicles

› Thermal Management Systems for and All Subsystems Vehicles and All Subsystems › Test and Evaluation

› Propulsion Systems › Computational Methods

› Propulsion Components › Hypersonic Fundamentals and History

ORGANIZED AND SUPPORTED BY: aiaa.org/Hypersonics2020 DECEMBER 2019 | AIAA NEWS AND EVENTS AIAA Bulletin