Popular Mechanics - USA (2018-07 & 2018-08)

@PopularMechanics JULY/AUGUST _ 201 21

the 1960s, the Air Force

was testing superson-

ic planes over Okla-

homa City. Residents

complained of broken

windows and dishes

falling from cupboards,

the result of sonic booms up

above—when the jets went past 767 mph,

outpacing the noise from their engines and

air resistance, those shock waves coalesced

into pressure that would release like biblical

thunder, damaging houses thousands of feet

below. That side efect is why, even 71 years

after Chuck Yeager’s irst supersonic light,

THE QUIET SUPERSON

I

C

JET

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, long-

distance travel. Then they added canards,

tures interrupt the pressure buildup that

causes a sonic boom. According to Lock-

heed, 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 toler-

IN

Several American aeronautics companies have been quietly build-

ing their own high-speed civilian planes. [A] Boom Supersonic,

founded by a former Amazon executive, has built a two-seat pro-

already has 76 pre-orders, with commercial lights planned for the

mid-2020s. Meanwhile, [B] Aerion Supersonic and [C] Spike Aero-

space 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.

THE

P

R

IV

A

A

C

B

NASA HOPES

YOU WON’T

NOTICE ITS

NEWEST

EXPERIMENTAL

PLANE.

BY JAY BENNETT