suburb of Denver, bustles with activity. In one corner, a
team assembles a mock-up of the Overture’s interior, which
features wide seats, wood trim, and a locker under each
berth instead of an overhead bin. Not far away, engineers
stress-test the carbon-fiber horizontal stabilizer—that’s the
little winglet on a plane’s tail—of the XB-1 demonstrator.
A growing collection of parts, including a pile of Goodyear
aircraft tires, fills one room. Here and there you see models
of the airliner, ambitiously sporting the liveries of carriers
from around the world. At 170 feet long, the jet will be a bit
shorter than a Boeing 777. With a pinpoint nose and triangu-
lar delta wing that spans just 60 feet, it will look like a dart.
A full-size mock-up of the demonstrator, which will carry
two people at 1,400 mph, sits in the middle of the hangar.
Airplanes are typically designed around their engines,
and the ones that will power the Overture are perhaps its
greatest barrier to success—because they don’t exist. For
its business to work, Boom needs a propulsion system far
more fuel efficient than its demonstration plane’s J85s or
even the Rolls-Royce/Snecma Olympus 593 turbojets the
Concorde used. That means ditching the afterburner that
injects fuel into the exhaust for a second kick of thrust.
This extra boost used to be essential for supersonic flight,
but aviation tech has come a long way; the newest Mach
fighters can speed along without afterburners. “Mod-
ern engine technology will get you all the thrust you need
without them,” Scholl says.
Trouble is, no one makes an engine that’s both capable
of supersonic speed without an afterburner and able to
generate enough range for airline use. Rolls-Royce, Pratt
& Whitney, and GE are developing proposals, but no one’s
discussing specifics for the Boom effort yet.
Assuming it does produce a powerplant with the
needed specs, Boom will have to go through its own aero-
dynamic contortions to make it work. The company’s
engineers are developing a variable-geometry air inlet
for the XB-1 that will maximize efficiency at both super-
sonic cruising velocities and the relatively slow pace
required for takeoff and landing. The carbon-fiber inlet
has a hinged flap that lets it change size. At Mach speed,
that flap angles upward into the airflow to create a smaller
opening, impeding the air coming in while cruising so it
flows through the turbine at the right speed and pressure.
When going subsonic, the panel retracts to allow the en-
gine to gulp the air required for everything else. It’s not
a part you find on many aircraft, and data from recent
wind-tunnel tests suggests Boom’s inlet works. “It’s one
of the most complex pieces of the airplane,” Scholl says.
“Amazingly, we nailed it on the first try.”
Boom still has a long way to go though. Developing a
new airliner takes years in a process often rife with delays,
overruns, and missteps even before regulators dig into
things like manufacturing and flight-safety procedures.
The French and British consortium that developed the
Concorde spent 20 years and $37 billion (today’s dollars)
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