NASA busy verifying Aerion SBJ's Mach 1.6
Aerion, based in Reno, Nev., is at Booth No. 6202 in NBAA exhibit Hall C to describe preliminary results from the latest round of flight tests of a NASA F-15B on the road to what it envisions as the worlds' first supersonic business jet (SBJ). The tests during July and August in collaboration with NASA's Dryden Flight Research Center achieved a top speed of Mach 2.0. The flights at Edwards AFB, Calif., marked the latest milestone in preliminary engineering activities directed toward a design capable of cruise speeds up to Mach 1.6 Dr. Richard Tracy, Aerion's chief technology officer, is in Atlanta to provide details on the tests and explain the video being presented at the Aerion booth, which documents the five-flight test series. Tracy has collaborated with NASA on supersonic natural laminar flow flight research since the early 1990s, and the Aerion research team has conducted supersonic flight tests with NASA since 1999. "Future tests will evaluate supersonic boundary layer transition properties as they relate to manufacturing standards for surface quality and assembly tolerances, both of which are crucial to future production of Aerion's supersonic business jet," said Tracy. Using upgraded infrared digital imagery, Aerion and NASA have begun a two-phase program, the first structured to better understand and document the flow field beneath the NASA flight test F-15B, to which various test articles were attached. The flights measured pressures to be used in wing performance computations, calculate shock fields around the engine inlet and determine means of compensation. Flight data is being compared with an SBJ computational model. The next test series, planned to begin in the second quarter of next year, will deal with the effect of wing surface imperfections on laminar flow and its transition to turbulent boundary layer flow. Emphasis will be on the interaction of surface defects and airflow to quantify permissible surface imperfections in manufacturing and operations. A device incorporating SBJ wing section elements will be mounted beneath the flight test aircraft. Final SBJ wing design will follow Phase Two flight tests, using laminar flow data from wind tunnel sessions refined by in-flight test measurements. Tracy said the design goal is to minimize cross-flows over most of the wing and avoid premature laminar-to-turbulent boundary layer flow transition. Subsonic Operations Aerion's SBJ, designed to carry eight to 12 passengers efficiently at high subsonic as well as supersonic speeds, has attracted letters of intent for roughly 50 aircraft with accompanying $250,000 deposits for the $80 million aircraft, all held in escrow. This $4 billion order book has remained relatively constant despite recent economic volatility, said Doug Nichols, Aerion's chief financial officer. He added that the company is engaged in ongoing talks with business aviation airframe companies as it seeks to negotiate a joint venture with a major OEM. Nichols estimated that aircraft deliveries would begin five to six years from the formation of a joint venture. "We're making progress, and we're encouraged," he said. "We've made it clear that our design is compatible with current noise and environmental standards." He added that a major Aerion design selling point is that the SBJ will economically operate at high subsonic airspeeds as well as fly at up to Mach 1.15 without sending a sonic boom to the surface. "That flexibility of operation is a huge plus for us." Nichols emphasized that while the possibility exists for future approval of supersonic flight over the U.S., the Aerion SBJ business model does not depend on it for economic viability and assumes conformity with Stage 4 noise and all other present environmental regulations. Nichols and Tracy agreed that a hurdle greater than sonic boom at cruise is noise in the takeoff environment. This stems from the fact that current quiet, high-bypass turbofan engines are not compatible with supersonic flight. Tracy said Aerion is looking at a Pratt & Whitney JT8D-19 variant that has potential for supersonic operation while meeting Stage 4 noise levels. Results from this summer's initial series of data flights aboard NASA's F-15B have been analyzed by comparing static pressures recorded at 60 points at varying speeds and altitudes with those predicted by aircraft computer models, Tracy explained. Engine inlet parameters are included in the model and adjustable to achieve the best fit with the measured pressures. "This process has been completed and the design of a test article to be used in the next series is well along," he said. Design goals include achieving the maximum extent of supersonic laminar flow, confirmation of its robustness under realistic conditions and quantifying cross-flow pressure gradients. When the aerodynamic optimization of the new test article has been completed, Aerion will carry out mechanical design and fabrication to NASA flight test criteria. Then, after NASA ground and flight qualification, the second phase of the tests will commence. Aerion was formed in 2002 to reintroduce commercial supersonic flight. It emerged from an advanced engineering group that began work more than 20 years ago. Its current focus is design of a practical and efficient supersonic business jet employing patented natural laminar flow technology. Aerion's board includes Brian Barents, former president and CEO of Galaxy Aerospace and Learjet; Tracy, who has pioneered the supersonic natural laminar wing concept; and COO Michael Henderson, Boeing's former program manager for high-speed civil transport.