Downloaded from http://asmedigitalcollection.asme.org/memagazineselect/article-pdf/138/03/36/6359754/me-2016-mar2.pdf by guest on 27 September 2021 BACK TO THE SOUND BARRIER Shock wave of the supersonic T-38C over the Mojave Desert. Photo: NASA MECHANICAL ENGINEERING | MARCH 2016 | P.37 The market for supersonic business jets such as the AS2 is expected to be only about 30 per year. Illustration: Aerion Corp. Downloaded from http://asmedigitalcollection.asme.org/memagazineselect/article-pdf/138/03/36/6359754/me-2016-mar2.pdf by guest on 27 September 2021 BUSINESS JETS RACE FOR THE SUPERSONIC PRIZE BY GREG FREIHERR ast September, a delegation of executives from Airbus Defence and Space, the European aerospace consortium, spent four days in the offi ces of Reno- Lbased Aerion Corp. Though the companies had been partners for more than a year, this was the fi rst time senior engineers and project managers from both companies had met to discuss their joint development, a business jet called the AS2. Executives and managers from the two companies reviewed the engineering on every structure and system on plane. If all goes as planned, in 2023 business It will be Aerion’s job to build the business travelers be able to board an AS2 and fl y faster jet. Airbus, a premier manufacturer of com- than the speed of sound. mercial aircraft, will be a “tier-one supplier of “It showed us the great progress we had aerostructures,” Nichols said. Airbus is already made in one year of collaborative effort providing Aerion with design tools, as well as and set a clear path for our next steps,” said advising the company “in a number of engi- Aerion’s CEO, Doug Nichols, who described neering and program management areas.” the effort as the “only supersonic program The partnership will bear fruit with the to have shifted into the aircraft development fi rst supersonic fl ight of its AS2 business jet in program phase.” 2021, Aerion spokesman Jeff Miller said. He Downloaded from http://asmedigitalcollection.asme.org/memagazineselect/article-pdf/138/03/36/6359754/me-2016-mar2.pdf by guest on 27 September 2021 Research by Boeing and NASA has been aimed at increasing fuel efficiency and reducing noise. Photo: NASA said the company expects certification and entry into service in 2023. The Aerion-Airbus partnership is one of a half dozen or so ventures looking into supersonic trans- ports. Among them is Spike Aerospace, whose slick artist renderings show an 18-passenger business jet that company founder Vik Kachoria promises will one day cruise at Mach 1.6. Spike is targeting 2018 for the first supersonic test flight of a “rudimentary, proof of concept” prototype and 2022 for delivery of its first production model, Kachoria said. The schedule is “very aggressive, very ambitious,” he said. “But we also recognize that our investors have a time horizon.” Gulfstream, which makes the G650 Flexjet, a leading business jet, has conducted supersonic Dark horses with a declared interest in develop- research, but has not publicly discussed plans for a ing supersonic business jets are Reaction Engines supersonic aircraft since the early 1990s. Its former and Supersonic Aerospace International. partner, Russian aircraft maker Sukhoi, however, Although Reaction Engines focuses primarily on may still be interested, having displayed a model of propulsion, the company claims to have designed a supersonic business jet two years ago at a Moscow two airframes, one capable of Mach 5, another of air show. suborbital flight. Dassault Aviation, the French maker of business The CEO of Supersonic Aerospace is J. Michael jets and military fighters, showed interest in the late Paulson, who has said that he wants to carry on 1990s, but has said little since. the vision of his father, Allen Paulson, the one-time MECHANICAL ENGINEERING | MARCH 2016 | P.39 owner and CEO of Gulfstream who, before his speeds between Mach 1.2 and Mach 1.6. About the Downloaded from http://asmedigitalcollection.asme.org/memagazineselect/article-pdf/138/03/36/6359754/me-2016-mar2.pdf by guest on 27 September 2021 death in 2000, worked with Lockheed Martin to time it is ready to fly commercially, possibly as early design a supersonic business jet. as 2023, the market could support annual sales of Two aerospace goliaths with supersonic trans- 30 supersonic business jets, according to Aboulafia. port programs, Lockheed Martin and Boeing, are That’s enough volume for one provider. decidedly old school. The N+2 design by Lock- “But it has to be just one player,” he said. “If it’s heed Martin would seat 80 passengers; the Boeing two, they are going to lose their shirts.” ICON-II would seat 120. With fewer passengers, business jets would be Their designs have a place in the past but not far smaller than the Concorde. Along with im- the future, according to Richard L. Aboulafia, vice provements in design and engineering and the president of analysis at the Teal Group, an aero- use of lighter materials, they promise improved space and defense consulting company. The chief performance and increased range. This makes for reason is that their designs would require public an economically viable supersonic transport with a subsidies to operate. price in the range of $120 million per plane, accord- “The Concorde-size SST will never ever happen ing to Aerion. again,” he said. “The good old days of taxpayers This stratospheric price—about twice that of generously giving billions of dollars to rich people a Gulfstream G650—won’t be hard to swallow. have become passé.” Aboulafia said interest in top-end business jets “has The Concorde, which last carried passengers in exploded in the last couple of decades, not only in October 2003, was first conceived in the 1950s. The terms of total demand but in what people will pay.” French and British governments paid Aérospatiale The market may be willing, but the next genera- (whose assets were acquired by Airbus) and the tion of SSTs must meet several technical challenges British Aircraft Corp. billions of dollars to develop to get off the ground. Supersonic business jets will and build the Concorde, then provided subsidies have to combine a powerful engine with a fuel-effi- to Air France and British Airways to operate the cient design; demonstrate low emissions, especially planes. The Concorde existed in “a moment in time at high altitudes where the ozone layer is vulner- when technology was funded by the state without able; and abide by tough airport noise standards. any thought to earning money,” Aboulafia said. An even bigger concern, say many in the aero- Current efforts to return civilians to faster than space industry, is what they believe led to the sound travel are all privately funded. downfall of the Concorde: a ban on civilian super- sonic travel over land and territorial waters. This ban, enacted in the mid-1970s by the Federal Avia- ROOM FOR ONE tion Administration and stretched around the globe by international regulators, limited demand for the Aerion’s 12-seat tri-engine AS2, unveiled in Concorde to airlines with ocean routes. spring 2014, is designed to have a range up to 5,000 Aerion, on the other hand, contends that fuel nautical miles; reach 51,000 feet; and cruise at efficiency is more important than reducing sonic The AS2 business jet: Aerion and Airbus hope to have it in the air by 2021, NASA and Lockheed Martin have been exploring a variety of options for quieting sonic booms. This artist's conception of the N+2 concept shows a vehicle shaped to reduce sonic shockwaves and reduce drag. Image: NASA/Lockheed Martin Downloaded from http://asmedigitalcollection.asme.org/memagazineselect/article-pdf/138/03/36/6359754/me-2016-mar2.pdf by guest on 27 September 2021 booms. Aerion’s market surveys have documented 1950s with Neil Armstrong fl ying the demand for a “not everywhere” supersonic busi- plane,” Tracy said. “We were pleased ness jet that would fl y effi ciently at subsonic speeds to fi nd that it [laminar fl ow] happened over land and supersonically over oceans. before, but we found those reports after To achieve those effi ciencies, Aerion relies on we had settled on our wing shape.” what it calls natural laminar fl ow, said Richard Unlike the AS2’s stubby wings, the delta wings Tracy, the company’s chief technology offi cer. It that characterize competitors’ designs are “swept” protects the boundary layer, the thin sheet of air to minimize drag at supersonic speeds. Natural that fl ows over the skin of the airframe. Increasing laminar fl ow, leveraged in the AS2 design, reduces speed can disrupt this layer and increase drag. drag at supersonic speeds, as well as at subsonic, Natural laminar fl ow, which smooths the bound- thereby improving fuel effi ciency and range, Tracy ary layer, requires an unconventional wing design. said. The jet will also be able to cruise effi ciently A cross-section of a conventional wing looks like just below the speed of sound, at Mach 0.95 to 0.96. the top half of And that just might be necessary. Laminar Wing an elongated teardrop, with a fl at bottom and a BUSTING THE BOOMS curved top that tapers toward In its Strategic Implementation Plan, released in Conventional Flow Wing the rear. Aerion’s 2015, NASA states that “the viability of commercial natural laminar supersonic service depends on permissible super- fl ow wing looks sonic fl ight over land.” like a complete The wording of the Federal Aviation Administra- teardrop, with tion’s ban on supersonic fl ight actually gives SST tapering curves on both top and bottom.