general aviation

lofty ambitions Visitors to EAA AirVenture will be the first to glimpse Perlan 2, a glider that aims to take sustained flight to more than 90,000ft and the edge of space

HOWARD SLUTSKEN VANCOUVER The idea for the record flight attempt – ex- rent flowing over rocks: the air gets pushed pected to be staged next summer in Argentina into an invisible wave behind the range. aking its debut at EAA AirVenture – goes back 60 years, to when a young gliding Unique, lens-shaped lenticular clouds are 2015 is a new aircraft that is des- instructor called Einar Enevoldson volun- formed. The air inside the wave is smooth but tined to shatter records. The teered as line-crew in the US Air Force-fund- surrounding air can be violently turbulent. ­Airbus-branded Perlan Mission II ed Sierra Wave Project, in Bishop, California. Now an 83-year-old USAF and NASA M will use a little-known meteorological phe- Back then, the mountain wave weather phe- flight test veteran, Enevoldson is leading a nomenon called the Stratospheric Polar Night nomenon was little understood, and two Pratt- team of test pilots, programme managers and Jet to reach and fly at 90,000ft – piloted, Read PR-G1 gliders were flown into the wave meteorologists in an attempt to achieve the winged and sustained flight at over 27,400m. to gather meteorological and observational first unpowered flight to over 90,000ft. Perlan 2 will fly higher than the Lockheed data, reaching altitudes as high as 44,255ft. “You could see in the highest waves, it U-2 or SR-71, but it is not an exotically-shaped When strong winds cross a mountain seemed that there was some major motion or scramjet-powered superplane. It is a glider. range, the effect can be the same as a river cur- going on in the atmosphere at very high

24 | Flight International | 14-20 July 2015 flightglobal.com perlan mission II

nautical exploration and atmospheric scien- Perlan 2 will exploit tific research organisation. mountain wave winds Rather than starting with a pressurised in a bid to reach a ­design, the Perlan 1 was a modified DG record 90,000ft ­Flugzeugbau DG-505m glider. Double-glass canopies were installed to eliminate frost- over, along with a NASA high-altitude oxygen system and other mission-specific equipment. Enevoldson and Fossett wore pressure suits borrowed from NASA Dryden, and the team went to New Zealand for three seasons. Although data suggested that the best and strongest waves were there, Perlan 1 only reached 30,000ft. “I began looking for funding for the project, and eventually met Steve Fossett” Einar Enevoldson Perlan

“Steve wanted this to happen, and never gave up,” says Enevoldson. “We had no data from South America, but we looked at a map and saw El Calafate, in Patagonia, Argentina, at 50˚ south. The first year, we went there too late, but on the first flight of the second year [29 August 2006], we flew right into the ­primary wave, and went up to 34,000ft, climbing at 2,000ft/min.” But as the glider climbed through 36,000ft, the pilots’ pressure suits became progressive- ly stiffer, and they found it increasingly diffi- cult to manipulate the controls and equip- ment. “This was as expected, but more troublesome than we had hoped,” he says. “We were cold and tired,” he says. “We were actually at 51,500ft, and we knew our altimeters were accurate.” After the 5h flight, the data recorders were sent off for verifica- tion. However, a calculation error reduced the record-setting altitude to 50,671ft. The Perlan team recognised that a ­pressurised glider would be needed to reach higher altitudes. Some thought was given to “beefing up” an Alexander Schleicher ­ASH-25 glider, but the decision was made to

Airbus Perlan Mission II Airbus Perlan create the Perlan 2, a purpose-built ­pressurised glider. The Perlan 1 was eventu- ­altitude. Something was impinging on top of Still focused on high-altitude flight, in the ally donated to Seattle’s Museum of Flight, the wave field,” says Enevoldson. early 1990s Enevoldson saw a LIDAR image where it is on display. After a long and varied career as a USAF taken from an aircraft flying along the Arctic Tragically, in September 2007, Steve fighter and test-pilot at the NASA Flight Re- Circle. “It clearly showed the wave nature of ­Fossett was killed while flying in the Sierra search Center at Edwards AFB in California, the clouds at 80,000ft,” he says. “So I said Nevada mountains in California. And al- Enevoldson joined Grob Aircraft in Germany. that we should build a pressurised glider though the design and construction of Perlan and fly up to 80,000ft. I began looking for 2 continued, funding began to dry up. Look- research funding for the project, and eventually met ing for new partners, the project team met In 1988, he was the test pilot for Grob’s G-520 Steve Fossett. with Airbus in early 2014. Ken McKenzie, Egrett, an early “SigInt” aircraft capable of “After a serious negotiation lasting about deputy chairman and senior vice-president flying at 50,000ft for 8h. He also flew the 10 seconds, we decided to do it,” he laughs. for strategy and corporate development for Grob Strato 2C, a prototype high-altitude re- With Fossett’s support, Enevoldson founded US-based Airbus Group Inc, and a glider search aircraft. the Perlan Project, Inc, a not-for-profit aero- pilot himself, was in the initial meeting. ❯❯ flightglobal.com 14-20 July 2015 | Flight International | 25 general aviation

❯❯ “Before the meeting, I said ‘you can’t fly wave science a glider to 90,000ft’,” recalls McKenzie. “When we finished the meeting we said, How Can a Glider Climb to the edge of space? ‘how much do you need?’ We were so en- It all starts with the winter around 30,000ft in the mid- to thralled with the vision they had, and what weather in Antarctica. upper-tropopause, and climbs they had accomplished so far, that we had to Glider pilots around the well into the stratosphere, as be a part of this.” world regularly climb to alti- high as 130,000ft to At EAA AirVenture 2014, the project offi- tudes above 20,000ft, or even 140,000ft. The core winds of cially became the Airbus Perlan Mission II. 30,000ft, flying in the strong the night jet can reach an as- “For us, one of the key tenets of this project is lift found in mountain wave tonishing 260kt. the exploration and excitement of doing conditions. But for Perlan 2 to A number of meteorological something that’s never been done before,” reach 90,000ft, the pilots will factors will have to line up in says McKenzie. Within the company, the mis- need to jump into an express order to provide the optimal sion is part of Airbus Group Innovations, with elevator in the Andes, romanti- conditions for Perlan 2’s McKenzie overseeing Airbus’ involvement. cally named the Stratospheric flights, according to Austin. With funding in place to ensure the con- Polar Night Jet. Prefrontal conditions have to struction of Perlan 2, the glider’s components “The polar vortex comes occur during the relatively were taken out of storage and moved to RDD alive in Antarctica in the winter short, winter daylight flying Enterprises in Redmond, Oregon, where as- due to the tremendous cooling time, and the polar vortex and sembly was completed in June. at the poles, the sinking of the night jet have to be very active air, and the rotation of the and over Argentina. The lower pressurised globe,” explains Dr Elizabeth level jet and resulting wave Perlan 2 is constructed almost entirely of car- Austin, atmospheric physicist have to line up just beside, but bonfibre, primarily using pre-impregnated and the founder and president not under the night jet, and the carbon sheeting and tapes. The glider has a of Nevada-based orientation of both, relative to 25.6m (84ft) wing made up of four custom air- WeatherExtreme Ltd. She the Andes mountain range, is foil sections, with an aspect ratio of 27. The joined the Perlan Project in important. Mountain waves form airframe is designed to handle +6/-4g loads. 1998 as chief meteorologist, Perlan 2’s pilots will climb in distinctive lens- shaped With an empty weight of 574kg (1,260lb), the and developed the weather the lower level wave before clouds, seen here over gross weight will be approximately 816kg models used in both the penetrating the lift generated the Sierra Nevadas with two pilots and full mission equipment Perlan 1 flights and the upcom- by the night jet. If the polar on board. The cabin is a sealed compartment ing Perlan 2 missions to El vortex and the low level jet and will be pressurised to 8.5psi, giving a Calafate next year. stream are not properly higher and higher, they actually maximum in-cabin altitude of 14,000ft. “You get these sharp tem- aligned, the pilots will likely bend windward, and if they get “I decided a conventional [glider] canopy perature contrasts, and with have to transition through an steep enough, they will break. wouldn’t work for a pressurised cabin,” says the globe rotating, the jet area of weak climb around It creates extreme turbulence, Enevoldson. “I had a pretty good idea of what starts to form,” says Austin. “It 50,000ft. But if the conditions and could tear an aircraft the cabin should look like.” Perlan 2’s cabin circles the pole, and gets are exceptional, then the hori- apart.” has plug doors and rounded windows, set in a these kinds of tails that scoop zontal and vertical wind Getting accurate, timely configuration that has been successfully flight- away from it, and it wiggles and speeds in the night jet will in- data to feed the weather mod- tested by masking the canopy of conventional wobbles. Sometimes it pulls crease with altitude. “There’s el will be a challenge, says gliders to match the new aircraft’s design. away and become this tight jet, also a zone where we may ex- Austin. “The closest [balloon] “A lot of people compare our cabin design and sometimes it spreads perience ‘breaking waves’,” sounding is about 300 miles to SpaceShipOne,” says Morgan Sandercock, out.” The polar night jet starts says Austin. “As the waves get northeast of El Calafate, and project manager and pilot. “A couple of years

ago at Oshkosh, I got the chance to shake Burt a failure and we have to go to an open-loop Rutan’s hand. He said, ‘you’re using the same mode, we’ve got 20min in the system for an materials to solve the same problems, so of emergency descent.” In open-loop, the pilots course it looks the same!’” will breathe directly from the oxygen tank, Inside Perlan 2’s cabin, the pilots will use a bypassing the rebreather system. closed-loop rebreather system adapted from The pilots will use a custom-designed life existing underwater breathing technology, support system display to monitor and con- with each pilot on an independent system. trol the glider’s pressurisation and breathing The system feeds 100% oxygen, and will systems, and an LX Avionics LX-9000 vario- scrub carbon dioxide and moisture from the navigation system will be the primary flight pilots’ exhalations. A second tank, containing and information display. Perlan 2 will not be ordinary compressed air, will feed “make-up” equipped with an autopilot, but a yaw damp- air into the cabin, dealing with expected leak- er will be fitted. The scientific instrument age and preventing the oxygen content of the package will be mounted aft of the pressur- cabin air from exceeding 26%. ised cabin, utilising a CubeSat frame. The closed-loop system is very efficient, When meteorological data recommends a says Sandercock. “Using the rebreather func- launch (see panel above), the mission profile Enevoldson (left), Fossett and Perlan 1 irbus Perlan Mission II irbus Perlan

A tion the pilots can breathe for 8h. But if there’s will see Perlan 2 towed about 100km from El

26 | Flight International | 14-20 July 2015 flightglobal.com perlan mission II

Sandercock agrees: “It’s about 1,000km from El Calafate to Port Stanley in the Falk- land Islands. Downwind, we could do that in a couple of hours.” Payne, Enevoldson, Sandercock and Perlan 2’s other pilots will fly in the aircraft’s pres- surised cabin dressed as they do for lower-al- titude wave flights: in ski clothing, with down boots and electrically-heated socks. The cab- in’s carbonfibre-sandwich construction may “If you can match the wind speed you park there and go up like an elevator” Jim Payne Chief pilot

provide good insulation against the expected -57°C (-70°F) outside air temperature, says Payne. “The human body is like a 100W light bulb, and with the avionics in the cabin there’s actually a chance we might have a problem with too much heat in the cabin.” If an emergency descent from 90,000ft is ever required, Perlan 2 is equipped with a drogue parachute that has two separate acti- vation circuits. Payne explains: “It’s sized so that we can come straight down at 80KIAS –

Airbus Perlan Mission II Airbus Perlan 80 indicated at 90,000ft is pretty damn fast; a lot of sink rate!” In the case of a catastrophic the next closest is 600 miles Forecasting System, which will hole. We’re going to learn about airframe failure, the aircraft is also equipped north. A bunch of them are forecast conditions out for 48h the structure of the strato- with a ballistic parachute that is designed to launched on the Antarctic conti- at very high resolution. “We’re spheric mountain waves and be deployed at 10,000ft. nent, but those are inside the going to be watching it, not just the breaking waves. We’ll learn Perlan 2 will be on display at AirVenture, vortex. We’re hopefully going to to guide us when to launch, but how breaking waves impact and will head back to Oregon for initial flight launch our own soundings from where to tow,” she adds. energy, and transfer heat and testing in August. Payne will make the first upwind, which will transition Austin says that the science chemicals to and from the trop- flights, and once the glider’s basic through the atmosphere we’re generated by the Perlan 2 mis- osphere. That’s an important ­performance is determined, it will be fitted going to be flying in.” All of the sions will increase knowledge part of improving climate mod- out with the pressurisation and other mission- weather data will be fed into of our climate. “We’re going to els, because [current] climate related systems. The base will shift to ­Minden modeling software called the be studying ozone, because models don’t take breaking in January 2016, to flight test all of the glider’s Weather Research and we’re on the edge of the ozone waves into consideration.” ■ systems, and also to prepare ground crews and pilots. ❯❯

Calafate, with a release altitude of around wind speed is less than the glider’s best-per- 10,000ft, says Jim Payne, chief pilot. Payne, formance speed, the pilots will crab back and also an ex-USAF fighter and test-pilot, thinks forth to stay in the best climb region. But if the nothing of spending a day in a Schempp- pilots can match the wind speed, “you park Hirth Arcus glider, and flying a record-setting there and go up like an elevator”, Payne says. 972nm (1,800km) by running up and down Stall speed of Perlan 2 is predicted to be the Sierras from Minden, Nevada. 33KIAS at 90,000ft, with its never-exceed speed at 56KIAS. “We’ll figure out the mini- tropopause mum sink speed, and then we’ll know what “We expect the roll response to be slow at low to fly. I won’t be surprised if we spend a lot of altitude; any glider with that span is sluggish,” time at 36-38KIAS,” says Payne. says Payne. Perlan 2’s wing is designed to be Although the indicated airspeeds are low, most efficient in the 50,000ft range, with a the true airspeeds will add to Perlan 2’s re- 200ft/min minimum sink rate, reflecting data cords. That 36KIAS is equivalent to 242kt that shows the weakest climb will be in that al- (447km/h), true airspeed. The opposing titude region, just above the tropopause. wind speed is expected to be above 200kt, so Once the glider penetrates the wave, there “as we get high, we’d better be pointed The cabin is pressurised to 8.5psi are two basic flying strategies. If the opposing west”, chuckles Payne. Mission II Airbus Perlan flightglobal.com 14-20 July 2015 | Flight International | 27 perlan mission II

❯❯ The team will move to El Calafate in June 2016. “Hopefully we’ll get to at least 40,000ft in the Sierras. But when we get to Argentina, we’re not going straight to 90,000ft,” says Payne. The incremental test programme will see Perlan 2 carefully increase altitude before going for the 90,000ft goal. transonic After that, Perlan 2 will continue to fly mis- sions, between 90,000ft and 100,000ft. Once regular operations are established, scientists may fly in the back seat to operate research in- strumentation. Flight at 100,000ft and above may be possible, but Perlan 2 is likely to need new, transonic wings to reach that goal. One might wonder what can be learned from flying a glider into the stratosphere. The mission’s goals are meteorological research, Construction in aeronautical exploration and aerodynamic Oregon will be advancement, with a strong emphasis on edu- followed by flight cation to inspire future generations to pursue testing in Nevada careers in mathematics, science and research. Mission II Airbus Perlan vvw PERLAN 2 DESIGN Airbus’s McKenzie says: “Continuous flight in that realm is something that we don’t know anything about. As we look to the future, with airspace becoming more and more congested, 400” we may have to start looking higher and high- (10.16m) er. As well, the atmospheric parameters above o 3 87”(2.21m) 90,000ft approach those on Mars, so if we’re working on a spaceplane for a Mars mission, we can prove the concepts here. The data that is gathered will be a very useful outcome of the project. And I think Perlan 2 will strike a chord with the general public.” “Continuous flight in this 128”(3.25m) realm is something that we don’t know anything about” Ken McKenzie VP, strategy & corporate development, Airbus Group Inc 2.50o

Dennis Tito has already seen 90,000ft on 503” the altimeter, twice, during his Soyuz flights (12.78m) to and from the International Space Station in 2001. Tito is a major contributor and sponsor PERLAN 2 of the Perlan Project, and obtained his glider Crew 2 licence just a few years ago, at the age of 68. Cabin pressure 8.5psi He will be another of Perlan 2’s pilots, Empty weight 574kg (1,265lb) drawing on his 650h mountain wave gliding Gross weight 816kg (1,800lb) experience during the missions. Tito hopes Wingspan 25.6m (84ft) that Perlan will inspire a new generation. Wing area 263ft2 “Everything I’ve accomplished in my career Aspect ratio 27 can be linked to that interest as a young per- Wing incidence 1.5o son. I don’t see us having the kind of inspira- Horizontal tail -0.5 o tion in the area of spaceflight today that we incidence had 50 years ago. What can we do that would Va=52kt at 90,000ft = 350kt be new and exciting, to inspire young people? Vne=56kt at 90,000ft = 377kt I think Perlan is one opportunity.” +6.0/-4.0g “I think of this as an exploration,” Enevold- son adds. “There are parts of the earth that we haven’t explored, and I’m an explorer.” ■ flightglobal.com 14-20 July 2015 | Flight International | 29