The Lockheed Martin X59 is probably the strangest airplane ever designed.
Its razor sharp nose takes half of the airplane’s length there’s no cockpit in sight the wings
are tiny compared to the entire fuselage and its oversized tail engine looks like a weird
hump about to fall off.
Of course there’s a method to this madness.
The design is the secret sauce that has produced a true unicorn a supersonic jet that doesn’t
boom the hell out of people and buildings on the ground.
The sonic boom is a phenomenon that has long been the Achilles heel of supersonic flight.
When an aircraft travels faster than the speed of sound the compressed air molecules against
the body of the plane produce shockwaves that merge to form a sonic boom a loud and disruptive
noise heard on the ground.
This noise has historically been a significant impediment to the commercial viability of
supersonic flight over land.
The X59 is designed as an experimental jet that NASA will use to test just how big of
a boom people on the ground are willing to accept from a supersonic aircraft.
with this new design people shouldn’t expect much of a boom at all.
The X59’s quiet supersonic boom isn’t made possible by expensive magical materials
or exotic engines.
It really is just the shape of the aircraft.
the shape looks more like an anime alien spaceship than an actual vehicle created by human beings
that’s because it was dreamed up in another dimension by computers and humans through
special software created by the Bethesda, Maryland, company’s engineers.
Many of the problems that plague supersonic flight can be traced back to the Concorde
the famous supersonic passenger jet that could travel from New York to London in a mere three
and a half hours.
When the Concorde first took flight in 1969 people were enthralled by the idea of super
fast air travel.
It sounded like a technological marvel until they heard the actual sound.
As the passenger plane zoomed overhead and broke through the sound barrier it sent a
deafening boom to the ground below.
People described the sensation of a bomb dropping.
Glass windows shattered and doors trembled.
Unlike the X59 the Concorde wasn’t designed to be quiet.
Its delta-wing design with two very large triangular wings along its entire fuselage
that made it look like a paper airplane and powerful engines were contributors to the
sonic boom.
As planes started to go supersonic over the continental US the sound explosions became
so much of a problem that Congress banned supersonic flight over land in 1971 a move
that was later followed around the world.
The Concorde continued to fly until it was decommissioned in 2003 but most airlines couldn’t
justify the cost of operating the airplane if its supersonic abilities could be used
only over water.
In the decades after Congress passed the legislation banning supersonic flight over land NASA has
been on a mission to muffle supersonic booms.
But it wasn’t until recently that a silent supersonic jet became possible.
thanks to high speed computing and machine learning models that can accurately predict
the interaction of the sonic shocks and how they propagate down to the ground from an
altitude of 50,000 feet.
With this new technology in hand NASA sensed an opportunity to repeal the federal supersonic
ban.
It launched a program called Quesst or Quiet Supersonic Technology, to design and build
an X59 research aircraft that reduces the explosive sonic boom to a gentle thump.
In order to convince Congress to bring supersonic flight back into the mainstream NASA knew
it had to turn its low boom research into an actual experiment that would demonstrate
that an airliner could beat the speed of sound without breaking windows annoying millions
of urbanites and giving cattle heart attacks.
In 2016 NASA asked Lockheed Martin and a host of other companies to submit a proposal for
a test airplane that could demonstrate that supersonic flight over land was safe and as
silent as regular subsonic airliners.
The target was to make a plane with a boom of just 75 PLdB a volume unit that measures
how people perceive sound as opposed to the actual decibels produced by the sonic booms.
A 75 PLdB is the equivalent of hearing a dishwasher for less than a second.
For comparison the Concorde’s PldB was 105 or as loud as listening to a chainsaw at full
power.
In 2018 NASA awarded Lockheed Martin a $247.5 million contract to design, build, and deliver
the low boom X-plane.
The plane received its official moniker the X59 Quesst from the US Air Force in 2018 but
the company still had a long road ahead of it to develop a truly quiet supersonic jet.
Well before Quesst Lockheed Martin’s Skunk Works its legendary advanced aerospace design
group had already been working on what would eventually become the X59.
Back in 2013 the plane was known as C100 and it looked a little bit like a shorter version
of the Concorde with the engine right on its back splitting a V-shaped tail.
Designers used software to optimize details like the shape of the wings, the configuration
of the tail, and the length of the nose.
Eventually the CAD design turned into a scale model and the team tested it in a wind tunnel
where engineers could apply their learning to the following iteration.
Next came the C435 mode which used the V-tail design but had a much longer body with smaller
wings and a sharper pointy nose.
Then the C506 which got rid of the V-tail in favor of a traditional airplane tail after
they realized that the V made it harder to maneuver the airplane even though it was better
at reducing the sonic boom.
By 2015 the team had a design for the C603 which added a canard those two little winglets
that you can see near the cockpit at the end of the nose in the X59.
This model also pushed the engine farther back and set the wings at two different angles
first going up and then down around their midsection.
The C605 was the final prototype that informed the preliminary design of the X59.
They also learned that anything that causes discontinuity in the airplane’s shape for
instance a windshield or canopy can add to the boom effect.
This led them to get rid of the windshield altogether.
Instead the X59 uses an external vision system which is the only advanced technology in the
plane.
The pilot navigates using a camera viewing the outside through a large display.
This system had to undergo rigorous certification by the Federal Aviation Administration for
use in the national airspace.
Despite their best efforts to create a streamlined body the team found that bulges were inevitable.
the inlet for the engine was placed on top of the plane so the shock that’s generated
goes up into space rather than down to the ground.
This is what happened with the Concorde’s engines, which were under its wings.
The same thing goes for any actuators whose position on top will send shocks up instead
of down.
The X59 has been designed to manage and distribute shockwaves differently from the very start
while also flying at slower speeds than the Concorde, the Concorde’s cruising speed
was 1,350 mph while the X59 will cruise at around 925 mph.
By November 2018 Lockheed Martin had initiated the machining of the X59’s first part in
Palmdale California.
Major structural components were assembled by May 2019.
Fast forward to November 2022 and the General Electric F414-GE-100 engine which powers the
US Navy F18’s Super Hornet found its place in the X59.
The aircraft has since undergone a battery of tests from weight checks and fuel system
evaluations to ground vibration assessments.
Remarkably the X59 weighed in below the anticipated weight a rare achievement in aircraft development
that surprised the entire team.
However the journey hasn’t been without its challenges.
Currently the X59 is in the system checkout phase ensuring all systems are seamlessly
integrated and functional.
A planned maintenance and modification stand down was needed due to parts that took five
months to arrive.
This delay pushed the aircraft’s inaugural flight initially slated for December 2023
to early 2024.
We will have to wait a little longer to see the first flight of this magnificently weird
airplane.
After that there will be multiple tests in which the the X59 will be flown over cities
and rural areas the team measuring decibels and getting feedback from people on the ground.
If they achieve their objectives there’s no reason why aircraft manufacturers can’t
take the concepts they discovered and turn them into commercial airliners.
In fact one of NASA’s requirements for the project was that Lockheed Martin provide an
airliner design.
Lockheed’s vision for commercial supersonic air travel is a 200 foot long double the length
of the X59 twin engine model for 44 passengers.
Someday people might be able to look up and see an alien shape in the sky with the X59’s
design transcending experimental nature and ushering in a new era for high speed travel
across the globe.