OPENING^SPREAD:^ COURTESY^ BOOM^SUPERSONICTHE CONTROL ROOM AT THE U.S.
Air Force Academy’s Aeronautics Research
Center is remarkably quiet given the fury
Blake Scholl and his engineers just uncorked.
Thick concrete walls and a robust slab of glass
separate them from a screaming General
Electric J85-15, a turbojet like the one used in
the T-38 trainer and other military jets. The
cylindrical engine, bolted to a steel test stand, glows a sinister shade of
red as it spits a cone of flame the color of a clear summer sky.
Scholl, who founded Boom Supersonic in 2014, watches as his chief
test pilot, former U.S. Navy fighter hotshot Bill “Doc” Shoemaker, and
Boom propulsion engineer Ben Murphy coax the engine through its
runup to full afterburner: Fuel squirts into the exhaust, boosting the jet’s
thrust—and noise—by about 50 percent. All that energy barrels down an
exhaust port and out of the building, which is nestled in the foothills of
the Rocky Mountains in Colorado Springs, Colorado. In less than a min-
ute, the test, one of dozens Scholl’s team will perform, confirms that the
older-generation engine can handle the stress they’ll be subjecting it to.
The J85 is GE’s workhorse military turbojet. Three of them will power
Boom’s XB-1, a one-third-scale demonstration model of the $200 mil-
lion, 55-seat carbon-fiber airliner the company hopes to see streaking
across the sky at twice the speed of sound by 2025. It would be difficult88 SPRING 2019 • POPSCI.COM
to overstate the challenges Boom faces as it chases this
goal and all the ways its plan could go wrong. Seventy-one
years after Chuck Yeager punched through the sound bar-
rier in the Bell X-1, the Concorde and the Soviet Union’s
Tupolev Tu-144 remain the only airliners to achieve Mach
speed. Neither worked out. The Tupolev mostly carried
cargo, making just 102 flights with passengers. British Air-
ways and Air France lost money on most Concorde trips
despite exorbitant ticket prices and hefty government sub-
sidies. They grounded the airplanes in 2003 after 27 years
of glamorous—if fiscally strained—service.
The business case doesn’t appear much better today.
Even as Blue Origin and Virgin Galactic make steady
progress toward the day tourists will glimpse space
through the porthole of a rocket ship, no one’s figured out
how to make supersonic transport economically feasible.
The problem lies in maximizing fuel efficiency while re-
ducing engine noise and mitigating the sonic boom that
inevitably accompanies anything moving faster than the
speed of sound. When you throw in the requirement that
this tech turn a profit, the puzzle is so fiendishly difficult
to solve that Boeing and Airbus all but quit trying, launch-
ing precisely zero efforts since the Concorde’s last flight.T
photographs by Eric Adams