Nasa’s X-59 jet breaks the sound barrier without the boom, the future of flight just got real
“The main goal on the first flight is just to land,” X-59 project pilot James Less, who will fly future flights, tells WIRED. Less flew an F-15 fighter jet in X-59 formation as support aircraft during the inaugural flight and observed the new experimental jet for possible problems.
Revolutionary design aims to transform supersonic aviation
The X-59 Quesst (Quiet SuperSonic Technology), manufactured by Lockheed Martin’s Skunk Works, is designed to reduce the sound of sonic booms when an aircraft breaks the sound barrier. The successful inaugural flight marked a major milestone in efforts to develop quieter supersonic commercial aviation.
Also read: Quiet supersonic X-59 jet soars over California desert on first test flight
“X-59 is a symbol of American ingenuity,” NASA acting administrator Sean Duffy said in a statement. “It’s part of our DNA – the desire to go farther, faster and even quieter than anyone has ever gone before.” In the United States, commercial airliners are prohibited from flying at supersonic speeds over land due to disturbing sonic booms that shake windows and trigger alarms. Concorde, the only successful commercial supersonic jet, was limited to flying at supersonic speeds only over oceans.Engineering solutions to the sonic boom problem
When an airplane approaches the speed of sound, pressure waves form on the plane’s surface. These high-pressure areas combine into large shock waves when the aircraft moves supersonic, producing the double thunder of a sonic boom.
The X-59 will produce a lower “sonic sound” thanks to its unique design features. By giving it a long, thin nose that accounts for about a third of the overall length, engineers broke up the pressure waves that would otherwise coalesce with other parts of the plane. The engine was mounted above the X-59’s fuselage rather than below it as in a fighter jet; This provides a smooth underside that confines shock waves and directs sound waves upwards into the sky rather than towards the ground.
NASA aims to provide important data to aircraft manufacturers so that they can produce less noisy supersonic aircraft for commercial use in the future.
Unique aircraft features and components
The X-59 is a single-seat, single-engine jet that is 99.7 feet long and 29.5 feet wide, making it nearly twice as long as the F-16 fighter jet, but with a slightly smaller wingspan. The X-59’s cockpit and ejection seat come from the T-38 jet trainer, the landing gear comes from the F-16, and the control stick comes from the F-117 stealth attack aircraft.
Its engine, a General Electric F414 modified from the F/A-18 fighter jet, will allow the plane to fly at Mach 1.4, about 925 mph, at an altitude of 55,000 feet. This represents nearly twice the altitude and speed of typical commercial airliners.
Closed cockpit technology replaces traditional windows
The most notable change to the X-59 is the lack of a glass cockpit window. Instead, the cockpit is completely enclosed for maximum aerodynamic efficiency, and the pilot watches a camera feed of the outside world on a 4K monitor known as the eExternal Visibility System.
“When you look at a very shallow angle you can’t see through the glass very clearly, and so to have good optical qualities you have to have a certain steepness of the view screen, and that can create a strong shock wave that can really disrupt the low boom characteristics of the aircraft,” says Michael Buonanno, aircraft lead for the X-59 at Lockheed Martin.
Initial flight parameters and future test plans
On this first flight, the X-59 flew at a lower altitude and at approximately 240 mph, according to NASA. During future testing, the jet will slowly increase its speed and altitude until it reaches a top speed of about 659 mph at 55,000 feet, or 761 mph at sea level. The speed of sound varies with temperature and less pressure, causing the speed to decrease at higher altitudes.
“I look for something outside the plane that the pilot can’t see,” Less says of pursuit pilot responsibilities. Generally the first thing it checks is whether the landing gear has been successfully retracted, but on this first flight the X-59 deliberately left the landing gear down. “If the airplane is leaking any fluids, like fuel or hydraulics, you can usually see that as the chase pilot. I’m also looking for other traffic, air traffic, to point that out to him.”
Following the successful landing of the X-59 at Armstrong, NASA and Lockheed Martin engineers will review flight data to prepare for future faster flights of the jet.
Advanced technology enables low boom design
The eExternal Visibility System represents just one of the modern technologies required to build a low-boom aircraft like the X-59. Decades of computational fluid dynamics research and wind tunnel testing were also required to arrive at the final design.
“We’ve had the opportunity to really spend a lot of time applying computational fluid dynamics to these low-boom aircraft,” Lori Ozoroski, NASA’s commercial supersonic technology project manager, tells WIRED. “When you divide the space around it into things with a few million cells, we’ve moved away from that computational space around a plane with a few million cells, and now we’re pushing a billion cells.”
C.Immunity testing to gauge public response
Once the X-59 reaches supersonic speeds, the next step is to ensure that quieter sonic bursts are tolerable for people on the ground.
Also read: From New York to Los Angeles in just 3 hours? Supersonic travel may be back sooner than you think
“We’re planning a test campaign where we’ll fly over various communities in the United States and survey them and find out how angry people are,” Ozoroski says. The flights will produce both loud and quiet sonic bursts to see how people react. “Our plan is to collect all of this data, do about a month of testing at several locations around the country, and then present all of this data to the FAA and the international regulatory community to try to establish a robust limit rather than a speed limit.”
The future of commercial supersonic aviation
If successful, the program could pave the way for new commercial supersonic aircraft that would halve travel times; This is something companies like Boom Supersonic are trying to achieve.
The jet joins a line of innovative NASA X-planes that date back almost 80 years to the Bell X-1, which Chuck Yeager piloted on the first supersonic flight in 1947.
“I grew up studying Popular Science and Popular Mechanics and reading about X-planes at Edwards, and I never thought I would be in a position to do something like this,” says Less, who eagerly awaits his turn at the controls of the X-59. “This will be the most important moment of my career.”
