Page 11 - AAA MAY - JUNE 2019 Online Magazine

closer to reality. In partnership with NASA, the Lockheed Martin tices that account for potential technical risks
Skunk Works team is solving one of the most persistent challenges and budgetary uncertainty beyond the project’s
of supersonic flight – the sonic boom. NASA awarded Lockheed control. The X-59 QueSST is shaped to reduce
Martin Skunk Works a contract in February 2016 for the preliminary the loudness of a sonic boom to that of a gentle
design of X-59, designed to reduce a sonic boom to a gentle thump. thump, if it’s heard at all. The supersonic aircraft
NASA awarded a US$20 million contract to Lockheed’s team to will be flown above select U.S. communities to
design a low-sonic-boom X-plane that would support efforts to measure public perception of the noise – data
replace the current prohibition with a new standard that would that will help regulators establish new rules for
allow acceptable en-route supersonic noise. commercial supersonic air travel over land.

In 2018, Lockheed Martin Skunk Works was selected for the Michael Buonanno, chief engineer for NASA’s
design, build and flight test of the Low-Boom Flight Demonstrator Quiet Supersonic Technology (QueSST)
X-plane programme, said the foundation was
laid from 2010 to 2013 with the N+2 Supersonic
Validations Program. “We worked with NASA
to develop the necessary design tools and
experimental techniques to accurately shape
the vehicle so that its sonic-boom signature will
be perceived as a sonic heartbeat sound rather
than the typical loud double-bang that today’s
supersonic aircraft produce,” Buonanno said.
The QueSST jet would fly at speeds of Mach
1.4, about 1,100 mph, twice the speed of today’s
commercial airliners and nearly as fast as the
Concorde. Buonanno said boom-reduction
shaping tools have been validated by analysis,
wind-tunnel testing and flight experiments.

The X-plane’s promise hinges on its stream-
lined design. Its futuristic look includes a long,
(LBFD). The X-59 aircraft will collect community response data slender fuselage, a highly swept delta wing and
on the acceptability of the quiet sonic boom generated by the multiple control surfaces to tailor the distribu-
Lockheed design, helping NASA establish an acceptable com- tion of pressure and lift around the vehicle.
mercial supersonic noise standard to overturn current regulations “In order to have low sonic boom, you need to
banning supersonic travel over land. “This would open the door to specifically design to have it,” Buonanno said.
an entirely new global market for aircraft manufacturers, enabling “It’s a nuanced and detail-oriented task to set
passengers to travel anywhere in the world in half the time it takes up the shape of the vehicle so that the shock
today,” Lockheed Martin X-59 is designed to cruise at 55,000 feet waves that result from supersonic flight don’t
at a speed of about 940 mph and create a sound about as loud coalesce and result in that loud double-bang.”
as a car door closing, 75 Perceived Level decibel (PLdB), instead In the airline industry’s current tube-and-wings
of a sonic boom. model, shock waves largely roll off and then
meld into a sonic boom. The aerodynamic
In November 2018, NASA had officially committed to a develop- X-plane, however, is designed to scatter multi-
ment timeline that would lead to the first flight of its X-59 Quiet ple shock waves and minimize their cumulative
Supersonic Technology (QueSST) aircraft in just three years. This effect, producing only a rumble or soft thump.
critical milestone comes after a rigorous review, Key Decision
Point-C (KDP-C), that confirmed NASA’s continued support of the “You try to minimize the strength of the shock,
X-59, in terms of funding, and established an achievable devel- so you have a very sharp nose on the aircraft,
opment timeline for NASA’s first piloted, full-size X-plane in more but you have to extend it a long way past the
than three decades. fuselage,” said Thomas Corke, professor of
engineering at the University of Notre Dame.
“This aircraft has the potential to transform aviation in the United Corke, Director of Notre Dame’s Institute for
States and around the world by making faster-than-sound air travel Flow Physics and Control, conducted hyper-
over land possible for everyone,” said NASA Administrator Jim sonic Mach 6 experiments at the Air Force
Bridenstine. “We can’t wait to see this bird fly!” Academy in Colorado—at a speed more than
four times faster than the X-plane’s.
KDP-C commits NASA to the full X-59 development effort through
flight-testing in 2021. The cost and schedule commitments outlined “The idea is that there is no way to avoid a
in KDP-C align the project with programme management best prac- shock wave supersonically,” Corke said. “The

ASIAN AIRLINES & AEROSPACE May/June 2019 | 11