Aerion, which has been defining and refining its design for a supersonic business jet (SSBJ) for the past 11 years, is here at EBACE (Booth 7030) still quietly confident that it will someday be able to add the word “producer” to its résumé. To that end, a NASA F-15 has been flying this spring from Dryden Flight Research Center in California with an 80- by 40-inch section of Aerion airfoil attached to its belly. This second phase of flight-testing is intended to validate Aerion’s most crucial theory and measure “the real-world robustness of supersonic natural laminar flow.”
Aerion CEO Doug Nichols told EBACE Convention News late last month that he expects the test article will fly about a dozen times. Failure of the afterburner on the F-15’s right engine (while climbing out on a mid-April test flight) had put a kink in the test card by limiting testing to high subsonic speeds, he said, but with the engine and afterburner replaced he was confident the testing to Mach 2 would continue. The profile for the week before the end of April was to climb to 50,000 feet and then make a constant-Mach descent down to 40,000 with a few sideslips, using infrared thermography to assess the transition on the test article.
The new test article was engineered to accommodate aerodynamic non-uniformities under the F-15B, while also being sufficiently representative of the Aerion wing to evaluate the effect of surface imperfections on the stability of supersonic boundary layers. Information gleaned from these tests will help define manufacturing standards for surface quality and assembly tolerances, both crucial to future production of the SBJ, according to Aerion.
The test article is machined from aluminum, with thin layers of epoxy used for insulation and surface painting. Four resistive temperature devices located along the lower and trailing edges of the device provide highly accurate temperature readings from which to calibrate the infrared video, the primary instrumentation for the flight-tests. In addition, “the test article’s strong-back carries an array of five-hole probes that measure flow angularity near the leading edge,” the company said.
The previous round of tests during the summer of 2010 also reached Mach 2.0 and used an instrumented flat plate mounted to the same strong-back to map and enable computer modeling of the high-speed flow field under the F-15B. After analyzing the resulting data, aerodynamic design work for the new test article began in late 2010, followed by mechanical design in mid-2011 and fabrication in the first half of last year.
“The Aerion SBJ design uses patented applications of natural laminar flow for efficiency and speed, so understanding the parameters under which such an aircraft will be built and operated is fundamental to proving its viability,” said Dr. Richard Tracy, Aerion’s chief technology officer. “Our continued mutually beneficial relationship with NASA Dryden, plus a separate agreement with NASA Glenn Research Center on supersonic inlet software maturation announced last year, advances the theory and application of aerodynamics with the ultimate goal of safe flight at higher speeds compared to today’s subsonic civil aircraft.”
Aerion recently acquired Palo Alto-based Desktop Aeronautics and brought its four employees onto its payroll. These four people are “the senior PhD aerodynamicists at the heart of designing the digital tools Aerion has been using for the last decade,” according to Nichols. “Principally, we acquired the portfolio of intellectual property because it is fundamental to our design capability and is now the exclusive province of Aerion. Desktop also has a master distribution license for NASA’s Cart3D design optimization tool, which provides some independent revenue capability. The strategic wisdom of this acquisition has to do with the design tools, their proprietary nature and how closely coupled they are with Aerion’s own design aspirations for a supersonic business jet,” he said.
These advanced computational and optimization tools allow Aerion to design for minimum drag or maximum laminar flow, “which are really two different things,” said Nichols. “We tend to optimize for minimum drag. These tools allow us to optimize the integration of our straight thin wing with the fuselage and our propulsion system. It’s the know-how and cumulative experience of our designers coupled with our portfolio of proprietary wing designs that harness natural laminar flow and the suite of our optimization tools that allow us to move from conceptual to advanced design of the SSBJ itself, and also to help OEMs apply our knowledge to their high-subsonic/transonic aircraft. Our technology is eminently scalable.”
The numbers for the proposed Aerion SSBJ remain essentially unchanged: max cruise Mach 1.6, max long-range cruise speed Mach 1.4 to 1.5, max subsonic long-range cruise Mach 0.95 to 0.96 and 100,000 lb or less mtow. “It’s basically the same performance envelope but we are constantly reviewing and refining with a view to improving the design of the aircraft for the advent of Stage 5 noise requirements, for example, and longer range,” said Nichols. “It’s a constantly evolving project, but still fairly tightly contained around the performance parameters we’ve identified.”
“We continue to keep the OEMs apprised of our progress,” Aerion vice chairman Brian Barents told AIN, “and I think it’s fair to say there’s still a good level of interest worldwide among the handful of companies we consider to be viable candidates for partnership. Most of them have their hands full right now with their own internal projects and in some cases are dealing with a market that is dubious in its robustness. So they’re keeping their powder dry, and hopefully when all the stars are aligned we’ll be able to move forward.”
Asked whether Aerion has approached any Chinese enterprises, or vice versa, Barents said, “While we believe it’s a distinct possibility that there’s a Chinese entity [interested], we also believe that at this stage this project needs to be led by an existing bona fide aircraft manufacturer.”
Aerion’s payroll is currently approaching 20 people, plus another 20 or so with contractor status.
“The continued demand for big expensive airplanes during these lean years reinforces the market research we have previously done,” noted Barents. “Obviously, the success that Gulfstream is having with the G650, which sells for between $60 and $70 million, reinforces the fact that there remains a market for that size of airplane, as far as price goes. But it’s clear that speed is the next frontier, and we’re the only one offering an alternative there. So we believe that the market research we did about five years ago is still sound, and we’re bullish on the financial underpinnings of this project.” The proposed price of the Aerion SSBJ remains $80 million in 2007 dollars.
One of Aerion’s corporate catchphrases cleverly captures not only the program’s enduring “poised to happen” status but also the airplane’s purpose: “It’s a matter of time.”