Posted On Tuesday, June 26, 2012 at 08:16:47 AM
NASA’s aeronautical innovators are one step closer to confidently crafting a viable commercial airliner that can fly faster than the speed of sound, yet produce a sonic boom that is quiet enough not to bother anyone on the ground below.
The key to this recent advance came when wind tunnel tests of scale model airplanes verified that new approaches to designing such aircraft would work as hoped for when aided by improved computer tools, which were used for the first time together in each step of the design process.
Lockheed Martin team developed this design for a future supersonic aircraft. Bottom: A scale model at the NASA wind tunnel
“That was really the breakthrough for us. Not only that the tools worked, but that our tests show we could do even better in terms of reducing noise than we thought at the start of the effort,” said Peter Coen, NASA’s supersonic project manager at the Langley Research Center.
Nuisance noise generated by a commercial supersonic jet’s sonic booms during cruise, and by its powerful engines at takeoff and landing, has kept the speedy aircraft from entering service — except for Europe’s Concorde, which was limited to trans-Atlantic flights only. Only 20 concordes were ever built and they were put out of commission in November 2003.
Using the computer tools, teams led by Boeing and Lockheed Martin, and funded through NASA, came up with designs for two small supersonic airliners that would carry between 30 and 80 passengers and potentially enter service in the 2025 timeframe. The new jet is codenamed X-54.
“In bringing their design expertise to the process, these companies are not only addressing the low boom design elements, but all of the other aspects necessary,” Coen said.
For example, the computer tools show that one way to reduce the perceived loudness of a supersonic jet’s sonic boom is to change the aircraft shape, by lengthening the fuselage, making it more slender. Theoretically, the noise issue could be solved by a really, really long aircraft body.
Unfortunately, while an 800-foot-long airliner may lead to publicly acceptable sonic booms, an aircraft that size still must fit at its gate, make turns while taxiing to the runway without hitting anything and generally not require an expensive redesign of the nation’s airports.
“The long skinny fuselage is not a practical answer. In our pursuit of boom reductions, we examine the whole, 3D shape of the vehicle including the engine configuration,” Coen said. “Even then, we keep in mind that the airliner has to meet all of the other requirements.”
“The booms are still there, but your ear is tricked into hearing a thump,” Coen said. The ultimate aim for the X-54 is a London-to-Sydney flight that travels in excess of 4,000kmph and takes only four hours.