Lockheed Martin should complete a preliminary design review of its quiet supersonic X-plane by June and will move onto a critical design review with NASA, a Skunk Works programme lead says.

NASA just released the initial call for proposals for the demonstrator phase for the quiet supersonic technology (QueSST) aircraft programme, says Charles Chase, who manages the revolutionary programmes group at Lockheed Skunk Works. NASA dodged President Donald Trump’s axe in the fiscal year 2018 budget, with just a slight decrease to its overall budget and specific assurances for future over-land commercial supersonic flights. The president’s proposed budget provides $624 million for NASA aeronautics research and development. Both houses of Congress have also thrown their support behind QueSST, Chase says.

Lockheed’s characterisation of the low-boom supersonic demonstrator appears lighter than NASA’s earlier descriptions, which sketch a 25,000lb prototype. Lockheed and NASA will demonstrate a 9% scale model plane, weighing about 20,000lb and 90-feet long, in a high speed wind tunnel at NASA’s Glenn Research Center. The X-plane, powered by an existing GE F414 engine, will fly at Mach 1.4 at 55,000 feet, Chase says.

Lockheed will compete to build the demonstrator in the programme’s next phase.

“The idea there is to build a demonstrator we can fly around and gauge people’s annoyance by this new level of sonic boom,” he says.

Flight demonstrations will begin at NASA Armstrong Flight Research Center near Edwards Air Force Base, California, but NASA is planning to test the X-plane in communities across the country to gain a representative set of data and gauge people’s reactions to the sound, he says.

Skunk Works’ design promises to reduce the size of the sonic boom by more than 1000 times, reducing the effect of a window rattling burst to something closer to a car door slamming a few houses down the block, Chase says. Conventional aircraft create a sharp change in pressure over the vehicle, but the X-plane’s long, skinny fuselage and canards control the waves across the aircraft.

“We have tailored the lift distribution and the pressure that goes over the airplane so that the shockwaves no longer coalesce into this strong wave,” he says. “I must say coming up with this design was not easy. It took thousands of optimization runs with tools that we worked with NASA to validate over the years. We have the tools now in place that enable us to develop these sort of radical configurations.”

Source: FlightGlobal.com