Nasa reinvents Concorde – minus the noise
UNITED STATES: Supersonic flights could make a comeback within a decade after Nasa claimed to have solved the problem of the sonic boom that blighted Concorde.
Researchers say that computer simulations showed that a design by Lockheed Martin would reduce the thunderous double crack of a sonic boom to a distant grumble.
The aircraft’s contours are designed so that shockwaves do not reach the ground in the classic ‘‘N’’ wave form after it breaks the sound barrier but are more widely spaced. Lockheed was paid US$20 million (NZ$26.7m) by Nasa to develop the design in the first phase of a project intended to cut flight times and boost the US aviation industry.
Nasa will now receive applications from Lockheed and other companies to build a 30m flying prototype. It hopes data from test flights will convince regulators to lift the ban on supersonic flights over land which was implemented in the US in 1973, if aircraft meet noise standards.
Because of that ban Concorde could achieve its optimal cruising speed of 2146kmh only on transoceanic routes, limiting its viability. Nasa’s intention is that the technology it is developing will enable supersonic travel on many more routes. The first year of funding the project is included in President Trump’s budget proposal for 2018.
Lockheed’s concept is designed to fly at mach 1.4 (1728kmh), 55,000 feet above the ground. That is slower than Concorde, but the plane could cut flight times if overland flights are permitted. It would cut in half the six-hour flight time from New York to Los Angeles.
Peter Coen, Nasa’s project manager on the X-plane, said that the aircraft’s shape had been designed to prevent the pressure waves that are compressed when a plane travels faster than the speed of sound from coalescing into the two characteristic signals of an ordinary sonic boom.
Instead they would reach the ground in a staggered form.
He said: ‘‘It’s easy to achieve at the front of a plane but much harder when you get to the wings and engines. The [first-phase] design minimises sharp shocks, so that the perceived decibel level of the sonic boom falls from 105db on Concorde to about 75db. That’s like the difference between hearing the really loud crack of thunder when there’s a storm right on top of you, and the distant rumble of thunder some way off.’’
Lockheed Martin is keen to develop the working prototype, which will be tested from 2021, with Nasa aiming to secure regulatory approval from 2025.
Jock Lowe, a former Concorde pilot and past president of the Royal Aeronautical Society, said: ‘‘There’s a lot of investment in this technology, with interesting projects from Airbus and in China too. Nasa’s work could certainly help and I think supersonic flights could be reintroduced for business passengers on routes such as China to the US west coast within the next decade.
‘‘I’m more sceptical about overland supersonic travel any time soon.’’ - The Times