The Boom Stops Here
Hush, hush, sweet SST. Engineers are inventing a supersonic airplane that won't bust windows.
- By T.A. Heppenheimer
- Air & Space magazine, November 2005
(Page 3 of 6)
Northrop Grumman hopes to apply the results of the Shaped Sonic Boom Demonstrator tests to its military jets. “Success with the shaped sonic boom flight demo required us to advance supersonic aircraft design tools well beyond state-of-the-art,” says Charles Boccadoro, Northrop Grumman’s program manager of Future Strike Systems. “Supersonic designs represent a very attractive solution for the nation’s next-generation, long-range strike systems.”
“There’s a synergy involved with low-boom and efficient aerodynamics,” says Graham. “A lot of things needed for low-boom design have direct application to a strike system.”
Graham cites laminar flow research as a prime example of research with dual applications: “Whether you apply the principles of laminar flow to a business jet or a military airplane, its improved efficiency means that the aircraft can be smaller and lighter, thus helping the sonic boom problem.”
Northrop Grumman has its own idea of what a low-boom aircraft could look like: It would be extraordinarily slender, with thin, highly swept wings supported by a strut. To shield the shock waves created by the wing as well as additional shocks created by spilled air, inlets designed to spill very little air would be mounted above the wing. The cockpit would be so well faired into the fuselage the pilot would have to rely on TV cameras to see.
By applying these principles, several groups have already prepared low-boom designs for specific types of aircraft. DARPA has come up with a “dual-relevant” concept that could take form either as a military strike aircraft or a civilian business jet. Two features of the design catch the eye: Its wings are so sharply swept that although it is 170 feet long, its width is less than 58 feet. It also is extremely slender, with similarly svelte wings.
This summer, NASA awarded four industry teams $1 million grants each for a 5-month study to define the technology and design requirements for a quiet supersonic aircraft. The Sonic Boom Mitigation Project, as it is being called, will use the teams’ recommendations to develop a solicitation for proposals for an actual low sonic boom demonstrator.
“It will probably be an X-plane, although we don’t have a designation for it yet,” says NASA’s Bob Meyer, associate director for programs at Dryden. “We’re approaching this fairly aggressively. We hope to award the contract to the winning company early next year and perform flight tests in 2008.”
Meyer says the F-5 Shaped Sonic Boom Demonstrator tests were the catalyst for NASA’s continuing its research into shaping sonic booms. “However, those tests only addressed bow shock mitigation, or shocks from the nose of the aircraft,” he says. “The next step is to look at the whole airplane.”