The Quiet Supersonic Jet

The Quiet Supersonic Jet
NASA HOPES YOU WON’T NOTICE ITS NEWEST EXPERIMENTAL PLANE.
by Jay Bennett

In the 1960s, the Air Forcewas testing supersonicplanes over OklahomaCity. Residentscomplained of brokenwindows and dishesfalling from cupboards,the result of sonic booms upabove—when the jets went past 767 mph,outpacing the noise from their engines andair resistance, those shock waves coalescedinto pressure that would release like biblicalthunder, damaging houses thousands of feetbelow. That side efect is why, even 71 yearsafter Chuck Yeager’s irst supersonic light you have to be in the military if you want to ly faster than the speed of sound over land. (That’s also why the Concorde lew supersonic only over the ocean.)

But Lockheed Martin has an idea. Its engineers have designed the Low-Boom Flight Demonstrator (LBFD), a plane with aerodynamic technology that allows it to ly beyond the speed of sound without the noise of a typical sonic boom. Lockheed engineers started with a long, Concorde-like body and delta wing, ideal for high-speed, longdistance travel. Then they added canards, extra wings towards the front and a small T-tail at the rear. At speed, those extra features interrupt the pressure buildup that causes a sonic boom. According to Lockheed, this will reduce the typical 105-decibel thunderclap to a 75-perceived-level-decibel rumble, barely audible from the ground.

NASA has given the company a contract worth $247.5 million to build the LBFD, with first takeoff scheduled for summer 2021. After those irst survey lights, pilots will take the LBFD up to Mach 1.4 at 55,000 feet over populated areas of the United States. NASA will then canvass the people living below to ind out whether the sonic booms were tolerable. If succesful, the LBFD's findings will help determine the future of manned flight .

The Private Supersonic Players
Several American aeronautics companies have been quietly building their own high-speed civilian planes. Boom Supersonic, founded by a former Amazon executive, has built a two-seat pro  totype jet, the antecedent to a 55-seat passenger jet. Boom says it  already has 76 pre-orders, with commercial lights planned for the mid-2020s. Meanwhile,  Aerion Supersonic and  Spike Aerospace are building supersonic private jets. These smaller craft can hit the speed of sound, manufacturers say, without a loud sonic boom. All three companies are aiming for irst lights within the next three to four years.sources:
Popular Mechanics, July 2018

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