Coming soon: NASA’s X-59 will test its ‘sonic thump’ over communities
On Oct. 14, 1947, Air Force test pilot Charles E. Yeager became the first human being to break the sound barrier in level flight. His flight over the Mojave Desert created a thundering boom that was reportedly heard in Victorville and elsewhere.
But dreams of increased commercial use of supersonic flights were quashed in April 1973 when the United States banned the flights — largely because the big booms frightened people.
According to NASA, the ban’s introduction was strongly influenced by public opinion surveys in cities where supersonic military jets were flown overhead, and many folks said they didn’t like what they heard or the way their windows rattled because of the sonic booms.
Nils Larson, head test pilot for NASA, spoke to members of the Greater Tehachapi Chamber of Commerce at a luncheon meeting on May 16 and said the government agency is working on a new way to break the sound barrier and allow supersonic flight with the X-59.
Instead of a boom, NASA hopes to achieve supersonic flight with a sonic thump instead of a sonic boom.
Just how quiet will NASA’s X-59 be?
According to Larson’s presentation, the experimental aircraft will produce a barely audible sonic thump to people on the ground when cruising at supersonic speeds.
While the sound of the sonic boom from the Concorde — a commercial plane retired in 2003 — would sound to people on the ground a little louder than nearby thunder or the sound of a car door slamming from inside the car, the sound of the X-59 is expected to be perceived by people about the same as hearing a car door slam 20 feet away.
Proving a sonic boom can be reduced to a sonic thump could enable a new fleet of quiet, commercial supersonic aircraft that can fly over land, Larson said.
The X-59 is being built at the Lockheed Martin Skunk Works Facility in Palmdale, he noted, and is sometimes called a “Frankenplane” because it’s essentially being constructed with parts originally designed for other aircraft.
It uses a single GE-F-414 engine with a standard nozzle and a T-38 aft canopy and ejection seat. It has landing gear from the F-16 and other systems from high-performance aircraft. These features not only cut costs but also reduce the time needed to qualify the various elements.
It’s designed to fly at 55,000 feet — and only designed to function for 1,000 hours as part of NASA’s Quesst Mission.
Once the X-59 is complete, it will be flown over several U.S. communities to gather data on human responses to the sound generated during supersonic flight. NASA will deliver that data set to U.S. and international regulators.
Testing may also take place over Europe, Nelson said, because NASA learned
that people there are not as likely as people in the U.S. to have air-conditioning that might dull the sound of a boom.
Once data is available, new sound-based rules regarding supersonic flight over land can be written and adopted, opening the doors to the development of faster-than-sound air travel for commercial cargo and passenger markets.
The need for speed is related to global demand for air travel, which is
growing, Nelson said. And he added that supersonic products will lead to more high-quality jobs in the U.S. The government’s support, through NASA, will allow the development of larger, more capable airliners.
The X-59’s shape prevents shockwaves from coming together, reducing the loud sonic boom to a quieter thump.
A unique feature of the aircraft is that it doesn’t have a windshield for the pilot to view surroundings.