NASA and top U.S. defense contractor Lockheed Martin Corporation are together developing a supersonic aircraft that emits hardly any audible sonic booms in supersonic flight.
And why is this important? Because such a quiet supersonic airliner will allow flights over land, as well as enabling flights to reach their destinations so much faster. Existing U.S. aerospace regulations forbid commercial supersonic aircraft from operating over land, however.
The prototype aircraft that will attain this lofty aim is the Lockheed Martin X-59 QueSST ("Quiet Supersonic Transport") experimental plane, which officially entered production last week after less than three years since work on the project began. China has no aircraft of this kind of development.
What makes QueSST different from its famous predecessor, the Aérospatiale/BAC Concorde, which was retired in 2003, is the former won't generate ear-splitting sonic booms. Instead, QueSST will emit a low 75 Perceived Level decibel (PLdB) "thump." That sound is about as loud as the sound a car door makes when closing.
Last April 2, NASA awarded Lockheed Martin a $247.5 million contract to design, build and deliver a Low-Boom X-plane (the X-59) in late 2021. On June 26, the U.S. Air Force informed NASA it had assigned the X-59 QueSST designation to the demonstrator aircraft. The X-59 QueSST is designed to cruise at 55,000 feet and reach speeds of about 940 miles per hour.
The secret to the supersonic plane's noise-reducing capability is its uniquely shaped structure. The fuselage is designed so that supersonic shockwaves don't accumulate to create powerful sonic booms.
The X-59 will still generate multiple shockwaves because of the wings on the aircraft that create lift and the volume of the plane, said Ed Haering, an aerospace engineer at NASA's Armstrong Flight Research Center. The shape of the X-59, however, is carefully tailored such that those shockwaves do not combine. Instead of getting a loud boom-boom, the sound produced are two quiet thump-thump sounds, "if you even hear them at all."
Lockheed Martin and NASA want to advance quiet supersonic technology through noise reduction in order to overturn regulations that forbid supersonic planes from going supersonic over land. The X-59 is designed to return supersonic passenger air travel to routes over land.
The start of manufacturing the X-59 is a great leap forward for the new supersonic plane and the future of quiet supersonic commercial travel. The long, slender design of the aircraft is the key to achieving a low sonic boom, said Peter Iosifidis, Low Boom Flight Demonstrator program manager for Lockheed Martin Skunk Works. The X-59 will fly for the first time in 2021.
