DOCSLIB.ORG

Breaking the Real Sound Barrier: Achieving Quiet Supersonic Flight

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Breaking the Real Sound Barrier: Achieving Quiet Supersonic Flight Breaking the Real Sound Barrier: Achieving Quiet Supersonic Flight Aircraft Builders Conference Montreal Canada Peter Coen NASA Low Boom Flight Demonstration Mission Manager www.nasa.gov www.nasa.gov1 Presentation topics • NASA Aeronautics • Commercial supersonic flight background • What is a sonic boom anyway? • From boom to thump: Designing for quiet flight • How will we know if it’s quiet enough • NASA’s Low Boom Flight Demonstration • Concluding remarks 2 www.nasa.gov NASA: The National AERONAUTICS and Space Administration “The Big ”A” in NASA” 3 www.nasa.gov NASA Aeronautics NASA Aeronautics Vision for Aviation in the 21st Century U.S. leadership for a new era of flight 4 www.nasa.gov Innovation in Commercial Supersonic Flight Commercial supersonic flight represents a potentially large new market for aircraft WHY? manufacturers and operators world-wide The government plays a central role in • Global demand for air travel is growing, which places a demand on speed developing the data • Supersonic aircraft manufacturing offer the opportunity to establish a new needed for the market segment with significant export opportunity and high-tech job growth regulation change that is – Large potential market predicted: - business aircraft followed by larger essential to enabling commercial aircraft this new market – Technology leadership established through initial products will lead to development of larger, more capable airliners • Technologies reducing the environmental impact of supersonic aircraft may www.nasa.gov benefit subsonic aircraft as well The Vision for Commercial Supersonic Flight Overland Flight Restrictions based The emerging potential market has generated renewed interest in on unacceptable civil supersonic aircraft sonic boom noise • Evidenced by the appearance of several commercial programs even with are viewed as the existing restrictions on overland flight and other challenges main barrier to this vision The vision of the Supersonics Community is a future where fast air travel is available for a broad spectrum of the traveling public. • Future supersonic aircraft will not only be able to fly overland without creating an “unacceptable situation” but compared to Concorde and SST will be efficient, affordable and environmentally responsible www.nasa.gov Credit :Lockheed Martin Supersonic flight and sonic boom: A brief hhistory 1947 First supersonic flight Bell X-1 Sonic boom a novelty 1950s Rapid development of supersonic military aircraft F-100 Noise and damage concerns Extensive research into sonic boom XB-70 1960s Supersonic Commercial aircraft proposed Community studies determine sonic boom exposure is unacceptable to people 1973 US Federal ban, International limits Concorde 1976 – 2003 Concorde commercial service Supersonic operation only over the ocean 2003 DARPA-NASA Shaped Sonic Boom Demonstration SSBD First flight demonstration of theory for ”shaping” boom signature 2011 Breakthrough! Shaped signature in a practical aircraft design New approaches demonstrated by analysis and model testing Quiet Supersonic Concept www.nasa.gov What is a sonic boom? • Not the sound of an aircraft ”breaking the sound” barrier • Caused by instantaneous pressure changes called shock waves • Occurs continuously during supersonic flight www.nasa.gov 8 Why is a sonic boom so loud? What makes it annoying? Duration Pressure Change Rise Time Rounding www.nasa.gov 9 From ”Boom” to “Thump”: How is it done? www.nasa.gov 10 That doesn’t sound too hard…. Almost 50 years of research to solve the sonic boom noise problem Minimum 1960’s 2-D Geometry Overpressure Original math connecting the shape of the aircraft Minimum to the shape of the signature on the ground Initial Shock 1970’s-80’s 3-D Geometry Front Math improved to allow representation of actual aircraft geometry. Experimental validation Shaping Only 1980’s-90’s Segmented Nose Multiple, Computational models, new approaches to Similar breaking up shock waves, Experimental and flight Shocks validation Detailed Model of All Features Fully Shaped, Rounded Shocks 2000’s Fast, high fidelity computations New approach to selecting design goals. Maximized effects of the atmosphere 11 www.nasa.gov Quiet supersonic designs are within reach Breakthrough knowledge advancement • New methods for the design of aircraft with shaped sonic boom signatures • Shaping incorporated into practical, balanced designs • Design performance validated by wind tunnel tests • Sound level targets met for small airliner type aircraft; but methods are applicable to larger and smaller vehicles. www.nasa.gov 12 How will we know if it’s quiet enough? Studying response to sonic boom – Part 1: Laboratory studies • Sophisticated boom simulators - Laboratory reproduction of sonic boom sounds Simulation of - Consistent, repeatable test conditions boom sound • Study elements of boom that create annoyance as heard indoors - Goal: Understand how annoyance is related to spectrum, level, rattle, vibration Simulation of boom sound as heard outdoors www.nasa.gov 13 How will we know if it’s quiet enough? Studying response to sonic boom Part 2: Simulation with conventional aircraft • Current aircraft cannot generate low booms during straight and level flight • Sonic boom is generated during supersonic dive of an F/A 18 aircraft • Long propagation distance, significant attenuation, rounding Subsonic • Boom amplitude observed at house is adjusted by moving dive location relative to the house Boom Amplitude .1-.5 PSF Subsonic Boom Loudness 60-80 PLdB House Ground 10 to 20 miles www.nasa.gov 14 How will we know if it’s quiet enough? Studying response to sonic boom – Part 3: Limited community Studies • Dive maneuver creates new research opportunities • Realistic, varied structures and environments - Living & working conditions • Test conducted under approved supersonic flight corridors and a coastal city Galveston community test 2018 Structural & Acoustic Response Subjective Reaction www.nasa.gov 15 What do you think? Gunshot recorded “Thermometer” of Impulsive Sound Levels Firework Balloon pop Concorde sonic boom Nearby thunder Golf ball struck by driver Car door slam Hand clap Nail struck by hammer Perceived Level (dB) Level Perceived Car door slam outside the car Basketball bounce Range of sound level exposures in recent Distant thunder community tests Sonic “thump” design target Car door slam at neighbor’s house www.nasa.gov 16 16 Overcoming the Barrier to supersonic overland flight The Low-Boom Flight Demonstration Mission is specifically planned to generate key data for success in NASA’s Critical Commitment to support development of en route certification standards based on acceptable sound levels • New Environmental Standards are needed to open the market to supersonic flight • An En route Noise Standard is the biggest challenge – Requires proof of new design approaches – Must replace current prohibitions – No relevant data on exists to define limits • Community data from large, diverse population is a requirement – Standard must be accepted internationally www.nasa.gov NASA’s Low-Boom Flight Demonstration Mission Design Parameters • Length:96 ft • Span: 29.5 ft X-plane approach • Speed: Mach 1.42 (940 mph) focuses efforts on • Altitude: 55,000 ft defining minimum set of key requirements Timeline that can be met in the •2018 - Contract award most cost effective •2021 - First Flight design •2022 - Mission and Acoustic Validation •2023-25 - Community tests X-59 QueSST (Quiet SuperSonic Technology) Key Requirements Derived Requirements • The acoustic signal of the X-plane must effectively •New airframe design to achieve desired acoustic signal, with smallest size that meets replicate that of future larger supersonic commercial key acoustic requirements aircraft. •Use of components from existing aircraft to reduce cost (F-18 engine, T-38 canopy • The X-plane must conduct community overflight tests in and cockpit, F-16 landing gear, etc.) a manner representative of typical flight operations of •Payload capacity: single pilot/flight test instrumentation www.nasa.govfuture aircraft. 18 Concluding Remarks • NASA’s Strategic Plan for Aeronautics calls for leadership in Innovation in Commercial Supersonic Flight • Technical barriers to quiet supersonic flight have been overcome • Regulatory barriers in terms of prohibitions to overland flight need to be replaced with certification standards that enable innovation, but protect the public • NASA Aeronautics has made a commitment to deliver data on community response to quiet overflight sounds that will support the development of standards • The development of a new supersonic X-plane is the core of the NASA’s Low Boom Flight Demonstration Mission • Planning for community overflight tests is underway - NASA seeks to engage the international community to insure broadest applicability of data • Success in standards development will help industry realize a supersonic commercial market • NASA’s strategy also recognizes the importance of continued development to insure that future supersonic aircraft are compatible with developing aviation environmental initiatives www.nasa.gov 19.
Load more

Recommended publications
  • HISTORICAL PERSPECTIVE a Need for Speed
    n HISTORICAL PERSPECTIVE A need for speed Mach 0.8 to 1.2 and above the speed of powerful turbine engine available. To mit- Skystreak taught lots sound, respectively). The U.S. Army Air igate as much risk as possible, the team Forces took responsibility for supersonic kept the design simple, using a conven- about flight near research—which resulted in Chuck Yea- tional straight wing rather than the new ger breaking the sound barrier in the Bell and mostly unproven swept wing. The the sound barrier X-1 on Oct. 14, 1947. That historic event 5,000-lb.-thrust (22-kilonewton) Allison overshadowed the highly successful re- J35-A-11 engine filled the fuselage, leav- BY MICHAEL LOmbARDI search conducted by the pilots who flew ing just enough room to house instrumen- s World War II was coming to a the Douglas D-558-1 Skystreak to the edge tation and a pilot in a cramped cockpit. close, advances in high-speed aero- of the sound barrier while capturing new Because of the lack of knowledge about Adynamics were rapidly progressing world speed records. the survivability of a high-altitude, high- beyond the ability of the wind tunnels of The D-558-1 was developed by the speed bailout, Douglas engineers designed the day, prompting a dramatic expansion Douglas Aircraft Company, today a part a jettisonable nose section that could pro- of flight-test research and experimental of Boeing, at its El Segundo (Calif.) tect the pilot until a safe bailout speed was aircraft. Division. It was designed by a team led reached.
    [Show full text]
  • CHAPTER 11 Subsonic and Supersonic Aircraft Emissions
    CHAPTER 11 Subsonic and Supersonic Aircraft Emissions Lead Authors: A. Wahner M.A. Geller Co-authors: F. Arnold W.H. Brune D.A. Cariolle A.R. Douglass C. Johnson D.H. Lister J.A. Pyle R. Ramaroson D. Rind F. Rohrer U. Schumann A.M. Thompson CHAPTER 11 SUBSONIC AND SUPERSONIC AIRCRAFT EMISSIONS Contents SCIENTIFIC SUMMARY ......................................................................................................................................... 11.1 11.1 INTRODUCTION ............................................................................................................................................ 11.3 11.2 AIRCRAFT EMISSIONS ................................................................................................................................. 11.4 11.2.1 Subsonic Aircraft .................................................................................................................................. 11.5 11.2.2 Supersonic Aircraft ............................................................................................................................... 11.6 11.2.3 Military Aircraft .................................................................................................................................... 11.6 11.2.4 Emissions at Altitude ............................................................................................................................ 11.6 11.2.5 Scenarios and Emissions Data Bases ...................................................................................................
    [Show full text]
  • Airspace: Seeing Sound Grades
    National Aeronautics and Space Administration GRADES K-8 Seeing Sound airspace Aeronautics Research Mission Directorate Museum in a BO SerieXs www.nasa.gov MUSEUM IN A BOX Materials: Seeing Sound In the Box Lesson Overview PVC pipe coupling Large balloon In this lesson, students will use a beam of laser light Duct tape to display a waveform against a flat surface. In doing Super Glue so, they will effectively“see” sound and gain a better understanding of how different frequencies create Mirror squares different sounds. Laser pointer Tripod Tuning fork Objectives Tuning fork activator Students will: 1. Observe the vibrations necessary to create sound. Provided by User Scissors GRADES K-8 Time Requirements: 30 minutes airspace 2 Background The Science of Sound Sound is something most of us take for granted and rarely do we consider the physics involved. It can come from many sources – a voice, machinery, musical instruments, computers – but all are transmitted the same way; through vibration. In the most basic sense, when a sound is created it causes the molecule nearest the source to vibrate. As this molecule is touching another molecule it causes that molecule to vibrate too. This continues, from molecule to molecule, passing the energy on as it goes. This is also why at a rock concert, or even being near a car with a large subwoofer, you can feel the bass notes vibrating inside you. The molecules of your body are vibrating, allowing you to physically feel the music. MUSEUM IN A BOX As with any energy transfer, each time a molecule vibrates or causes another molecule to vibrate, a little energy is lost along the way, which is why sound gets quieter with distance (Fig 1.) and why louder sounds, which cause the molecules to vibrate more, travel farther.
    [Show full text]
  • Subsonic Aircraft Wing Conceptual Design Synthesis and Analysis
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by GSSRR.ORG: International Journals: Publishing Research Papers in all Fields International Journal of Sciences: Basic and Applied Research (IJSBAR) ISSN 2307-4531 (Print & Online) http://gssrr.org/index.php?journal=JournalOfBasicAndApplied --------------------------------------------------------------------------------------------------------------------------- Subsonic Aircraft Wing Conceptual Design Synthesis and Analysis Abderrahmane BADIS Electrical and Electronic Communication Engineer from UMBB (Ex.INELEC) Independent Electronics, Aeronautics, Propulsion, Well Logging and Software Design Research Engineer Takerboust, Aghbalou, Bouira 10007, Algeria [email protected] Abstract This paper exposes a simplified preliminary conceptual integrated method to design an aircraft wing in subsonic speeds up to Mach 0.85. The proposed approach is integrated, as it allows an early estimation of main aircraft aerodynamic features, namely the maximum lift-to-drag ratio and the total parasitic drag. First, the influence of the Lift and Load scatterings on the overall performance characteristics of the wing are discussed. It is established that the optimization is achieved by designing a wing geometry that yields elliptical lift and load distributions. Second, the reference trapezoidal wing is considered the base line geometry used to outline the wing shape layout. As such, the main geometrical parameters and governing relations for a trapezoidal wing are
    [Show full text]
  • The Mathematical Approach to the Sonic Barrier1
    BULLETIN (New Series) OF THE AMERICAN MATHEMATICAL SOCIETY Volume 6, Number 2, March 1982 THE MATHEMATICAL APPROACH TO THE SONIC BARRIER1 BY CATHLEEN SYNGE MORAWETZ 1. Introduction. For my topic today I have chosen a subject connecting mathematics and aeronautical engineering. The histories of these two subjects are close. It might however appear to the layman that, back in the time of the first powered flight in 1903, aeronautical engineering had little to do with mathematics. The Wright brothers, despite the fact that they had no university education were well read and learned their art using wind tunnels but it is unlikely that they knew that airfoil theory was connected to the Riemann conformai mapping theorem. But it was also the time of Joukowski and later Prandtl who developed and understood that connection and put mathematics solidly behind the new engineering. Since that time each new generation has discovered new problems that are at the forefront of both fields. One such problem is flight near the speed of sound. This one in fact has puzzled more than one generation. Everyone knows that in popular parlance an aircraft has "crashed the sonic *or sound barrier" if it flies faster than sound travels; that is, if the speed of the craft q exceeds the speed of sound c or the Mach number, M = q/c > 1. In simple, if perhaps too graphic, terms this means that if you are in the line of flight the plane hits you before you hear it. But it is not my purpose to talk about flight at the speed of sound.
    [Show full text]
  • Aircraft of Today. Aerospace Education I
    DOCUMENT RESUME ED 068 287 SE 014 551 AUTHOR Sayler, D. S. TITLE Aircraft of Today. Aerospace EducationI. INSTITUTION Air Univ.,, Maxwell AFB, Ala. JuniorReserve Office Training Corps. SPONS AGENCY Department of Defense, Washington, D.C. PUB DATE 71 NOTE 179p. EDRS PRICE MF-$0.65 HC-$6.58 DESCRIPTORS *Aerospace Education; *Aerospace Technology; Instruction; National Defense; *PhysicalSciences; *Resource Materials; Supplementary Textbooks; *Textbooks ABSTRACT This textbook gives a brief idea aboutthe modern aircraft used in defense and forcommercial purposes. Aerospace technology in its present form has developedalong certain basic principles of aerodynamic forces. Differentparts in an airplane have different functions to balance theaircraft in air, provide a thrust, and control the general mechanisms.Profusely illustrated descriptions provide a picture of whatkinds of aircraft are used for cargo, passenger travel, bombing, and supersonicflights. Propulsion principles and descriptions of differentkinds of engines are quite helpful. At the end of each chapter,new terminology is listed. The book is not available on the market andis to be used only in the Air Force ROTC program. (PS) SC AEROSPACE EDUCATION I U S DEPARTMENT OF HEALTH. EDUCATION & WELFARE OFFICE OF EDUCATION THIS DOCUMENT HAS BEEN REPRO OUCH) EXACTLY AS RECEIVED FROM THE PERSON OR ORGANIZATION ORIG INATING IT POINTS OF VIEW OR OPIN 'IONS STATED 00 NOT NECESSARILY REPRESENT OFFICIAL OFFICE OF EOU CATION POSITION OR POLICY AIR FORCE JUNIOR ROTC MR,UNIVERS17/14AXWELL MR FORCEBASE, ALABAMA Aerospace Education I Aircraft of Today D. S. Sayler Academic Publications Division 3825th Support Group (Academic) AIR FORCE JUNIOR ROTC AIR UNIVERSITY MAXWELL AIR FORCE BASE, ALABAMA 2 1971 Thispublication has been reviewed and approvedby competent personnel of the preparing command in accordance with current directiveson doctrine, policy, essentiality, propriety, and quality.
    [Show full text]
  • Introduction to Aerospace Engineering
    Introduction to Aerospace Engineering Lecture slides Challenge the future 1 Introduction to Aerospace Engineering Aerodynamics 11&12 Prof. H. Bijl ir. N. Timmer 11 & 12. Airfoils and finite wings Anderson 5.9 – end of chapter 5 excl. 5.19 Topics lecture 11 & 12 • Pressure distributions and lift • Finite wings • Swept wings 3 Pressure coefficient Typical example Definition of pressure coefficient : p − p -Cp = ∞ Cp q∞ upper side lower side -1.0 Stagnation point: p=p t … p t-p∞=q ∞ => C p=1 4 Example 5.6 • The pressure on a point on the wing of an airplane is 7.58x10 4 N/m2. The airplane is flying with a velocity of 70 m/s at conditions associated with standard altitude of 2000m. Calculate the pressure coefficient at this point on the wing 4 2 3 2000 m: p ∞=7.95.10 N/m ρ∞=1.0066 kg/m − = p p ∞ = − C p Cp 1.50 q∞ 5 Obtaining lift from pressure distribution leading edge θ V∞ trailing edge s p ds dy θ dx = ds cos θ 6 Obtaining lift from pressure distribution TE TE Normal force per meter span: = θ − θ N ∫ pl cos ds ∫ pu cos ds LE LE c c θ = = − with ds cos dx N ∫ pl dx ∫ pu dx 0 0 NN Write dimensionless force coefficient : C = = n 1 ρ 2 2 Vc∞ qc ∞ 1 1 p − p x 1 p − p x x = l ∞ − u ∞ C = ()C −C d Cn d d n ∫ pl pu ∫ q c ∫ q c 0 ∞ 0 ∞ 0 c 7 T=Lsin α - Dcosα N=Lcos α + Dsinα L R N α T D V α = angle of attack 8 Obtaining lift from normal force coefficient =α − α =α − α L Ncos T sin cl c ncos c t sin L N T =cosα − sin α qc∞ qc ∞ qc ∞ For small angle of attack α≤5o : cos α ≈ 1, sin α ≈ 0 1 1 C≈() CCdx − () l∫ pl p u c 0 9 Example 5.11 Consider an airfoil with chord length c and the running distance x measured along the chord.
    [Show full text]
  • Ping Pong Balls Break the Sound Barrier STEM Lesson Plan / Adaptable for Grades 7–12 Lesson Plan Developed by T
    INSIDE SCIENCE TV: Ping Pong Balls Break The Sound Barrier STEM Lesson Plan / Adaptable for Grades 7–12 Lesson plan developed by T. Jensen for Inside Science and the American Institute of Physics About the Video (click here to see video) Purdue University students, led by their mechanical engineering technology professor, designed an hourglass-shaped nozzle like those found in the engine of F-16 fighter planes for their air-cannon. The cannon accelerates a ping-pong ball to supersonic speeds, propelling it with incredible momentum through wood, soda cans, and even denting steel. Related Concepts acceleration energy momentum aerodynamics force sound barrier air pressure linear motion speed continuity equation mass vacuum Bell Ringers Use video to explore students’ prior knowledge, preconceptions, and misconceptions. Have students write or use the prompts to promote critical thinking. Time Video content Students might… 0:00–0:05 Series opening 0:06–0:13 What can travel at Have students make written predictions about supersonic speed and what might travel at supersonic speed and can shatter plywood? blast through plywood. Predictions should be supported with physics concepts. (You can play the video at full screen without the label Ping Pong Balls Break The Sound Barrier showing by keeping your cursor out of the screen.) 0:14–0:25 Purdue mechanical Students might put on their engineering hats and engineering and make annotated drawings that depict how they technology students build would propel a ping-pong ball to supersonic an air-powered cannon. speeds. 0:26–0:32 Students determine how Have students outline the procedure they would fast the ping-pong ball is follow to determine how fast the ping-pong ball traveling and makes was going when it hit the metal grid.
    [Show full text]
  • After Concorde, Who Will Manage to Revive Civilian Supersonic Aviation?
    After Concorde, who will manage to revive civilian supersonic aviation? By François Sfarti and Sebastien Plessis December 2019 Commercial aircraft are flying at the same speed as 60 years ago. Since Concorde, which made possible to fly from Paris to New York in only 3h30, no civilian airplane has broken the sound barrier. The loudness of the sonic boom was a major technological lock to Concorde success, but 50 years after its first flight, an on-going project led by NASA is about to make supersonic flights over land possible. If successful, it will significantly increase the number of supersonic routes and increase the supersonic aircraft market size substantially. This technological improvement combined with R&D efforts on operational costs and a much larger addressable market than when Concorde flew may revive civilian supersonic aviation in the coming years. Who are the new players at the forefront and the early movers? What are the current investments in this field? What are the key success drivers and remaining technological and regulatory locks to revive supersonic aviation? EXECUTIVE SUMMARY Commercial aircraft are typically flying between 800 km/h and 900 km/h, which is between 75% and 85% of the speed of sound. It is the same speed as 60 years ago and since Concorde, which flew at twice the speed of sound, was retired in 2003, there has been no civilian supersonic aircraft in service. Due to a prohibition to fly supersonic over land and large operational costs, Concorde did not reach commercial success. Even if operational costs would remain larger than subsonic flights, current market environment seems much more favourable: since Concorde was retired in 2003, the air traffic has more than doubled and the willingness to pay can be supported by an increase in the number of high net worth individuals and the fact that business travellers value higher speed levels.
    [Show full text]
  • Chapter Iv What Is the Thrust Ssc?
    THRUST SSC ENGLISH 2 – CHAPTER IV WHAT IS THE THRUST SSC? British jet-propelled car Developed by Richard Noble and his 3 asisstants Holds the World Land Speed Record 15. October 1997 First vehicle to break sound barrier DETAILS 16,5 metres long, 3,7 metres high, weights nearly 10 tons Two Rolls Royce engines salvaged from a jet fighter Two engines have a combined power of 55,000 pounds of thrust (110,000 horsepower) Two front and two back wheels with no tyres (disks of forged aluminium) Uses parachutes for breaking SAFETY OF THE CAR There is no ejection system in the car or any other kind of safety mechanisms The emphasis was placed on keeping the car on the ground HOW? Hundreds of sensors to ensure the vehicle to maintain safe path Aerodynamic system is there to keep the vehicle on the ground WORLD LAND SPEED RECORD The record set on 15th October 1997 The record holder is ANDY GREEN (British Royal Air Force pilot) WORLD MOTOR SPORT COUNCIL’S STATEMENT ABOUT THE RECORD The World Motor Sport Council homologated the new world land speed records set by the team ThrustSSC of Richard Noble, driver Andy Green, on 15 October 1997 at Black Rock Desert, Nevada (USA). This is the first time in history that a land vehicle has exceeded the speed of sound. The new records are as follows: Flying mile 1227.985 km/h (763.035 mph) Flying kilometre 1223.657 km/h (760.343 mph) In setting the record, the sound barrier was broken in both the north and south runs.
    [Show full text]
  • Sound Barrier Indexedmaster.Indd
    9 CONTENTS Page Chapter 15 1 FIRST FLIGHT 29 2 de HAVILLAND 47 3 NO TAIL 63 4 UNDERSTANDING THE SOUND BARRIER 69 5 SWEPT WINGS 85 6 BIRTH OF THE 108 101 7 YOUNG GEOFFREY 117 8 TESTING 133 9 FALLING LEAVES 147 10 NO WARNING 161 11 THE SHOW GOES ON 183 12 RECORD BREAKER 205 13 TRANSDUNAL TROUGH 216 14 SOUND BARRIER 227 15 FAREWELL HATFIELD 245 16 FARNBOROUGH 253 17 TRAGEDY 269 18 AFTERWARDS 291 APPENDICES Appendix I Discussion of aeroelastic properties of the DH108 II Discussion on the DH108 III Stressing assumptions IV Specification E18/45 V Pilot’s reports VI Meeting to discuss third prototype VII Report by John Wimpenny on flight tests VIII Summary by John Derry of flying DH108 VW120 IX Report by Chris Capper on approach and landing in DH108 TG/283 X Flight test chronology 10 11 INTRODUCTION It was an exciting day for schoolboy Robin Brettle, and the highlight of a project he was doing on test flying: he had been granted an interview with John Cunningham. Accompanied by his father, Ray, Robin knocked on the door of Canley, Cunningham’s home at Harpenden in Hertfordshire and, after the usual pleasantries were exchanged, Ray set up the tape recorder and Robin began his interview. He asked the kind of questions a schoolboy might be expected to ask, and his father helped out with a few more specific queries. As the interview drew to a close, Robin plucked up courage to ask a more personal question: ‘Were you ever scared when flying?’ Thinking that Cunningham would recall some life-or-death moments when under fire from enemy aircraft during nightfighting operations, father and son were very surprised at the immediate and direct answer: ‘Yes, every time I flew the DH108.’ Cunningham, always calm, resolute and courageous in his years as chief test pilot of de Havilland, was rarely one to display his emotions, but where this aircraft was concerned he had very strong feelings, and there were times during the 160 or so flights he made in the DH108 that he feared for his life - and on one occasion came close to losing it.
    [Show full text]
  • Section 7, Lecture 3: Effects of Wing Sweep
    Section 7, Lecture 3: Effects of Wing Sweep • All modern high-speed aircraft have swept wings: WHY? 1 MAE 5420 - Compressible Fluid Flow • Not in Anderson Supersonic Airfoils (revisited) • Normal Shock wave formed off the front of a blunt leading g=1.1 causes significant drag Detached shock waveg=1.3 Localized normal shock wave Credit: Selkirk College Professional Aviation Program 2 MAE 5420 - Compressible Fluid Flow Supersonic Airfoils (revisited, 2) • To eliminate this leading edge drag caused by detached bow wave Supersonic wings are typically quite sharp atg=1.1 the leading edge • Design feature allows oblique wave to attachg=1.3 to the leading edge eliminating the area of high pressure ahead of the wing. • Double wedge or “diamond” Airfoil section Credit: Selkirk College Professional Aviation Program 3 MAE 5420 - Compressible Fluid Flow Wing Design 101 • Subsonic Wing in Subsonic Flow • Subsonic Wing in Supersonic Flow • Supersonic Wing in Subsonic Flow A conundrum! • Supersonic Wing in Supersonic Flow • Wings that work well sub-sonically generally don’t work well supersonically, and vice-versa à Leading edge Wing-sweep can overcome problem with poor performance of sharp leading edge wing in subsonic flight. 4 MAE 5420 - Compressible Fluid Flow Wing Design 101 (2) • Compromise High-Sweep Delta design generates lift at low speeds • Highly-Swept Delta-Wing design … by increasing the angle-of-attack, works “pretty well” in both flow regimes but also has sufficient sweepback and slenderness to perform very Supersonic Subsonic efficiently at high speeds. • On a traditional aircraft wing a trailing vortex is formed only at the wing tips.
    [Show full text]