Is Supersonic Passenger Flight Possible Without the Signature Loud Sonic Boom?
A Subtly Audible Thump Sound
Indeed, it may just be a game changer if this were possible. Imagine going from New York to Paris in just under 4 hours. Now imagine a large fleet of faster-than-the-speed-of-sound capable passenger aircraft connecting international city pairs and domestic cities like Los Angeles and Chicago. A program known as Quesst is NASA’s latest attempt to make this a reality. NASA touts a concept aircraft called the X-59 as having the ability to punch through the sound barrier with nothing more than a subtly audible thump sound, as heard by a ground observer.
Data Gathered from the Program
The Quesst project is a survey of sorts. It is intended to survey people in residential neighborhoods and other areas for opinions on the sounds or thumps they hear when the X-59 aircraft is overhead. Ultimately, the data gathered from the program will be shared with aviation professionals and regulators who are tasked with determining what new sound-based rules should be implemented. This is vital to the X-59 program, as it will determine if the project will be viable and can move forward.
Concentric Waves That Ripple Outward in Every Direction
The final objective would be to lift the long-standing ban on faster-than-sound flights over land due to the disruptive sonic booms they produce. How is a sonic boom created? Suppose you are sitting poolside, and a child does a cannonball into the water. What happens? A big splash is followed by concentric waves that ripple outward in every direction. Now, think about an aircraft flying super-fast at altitude. Just like the child’s pool stunt, an aircraft makes waves, too, but in the air instead of water.
A Shockwave That is Far More Intense and Louder
They are invisible and are called sound waves. They move at the speed of sound, just like ripples in a pond. Then, something interesting occurs as the aircraft accelerates faster than the speed of sound. The sound waves begin to compress and stack up in front of the wing, like a traffic jam. This eventually generates a shockwave, kind of like when you clap your hands fast. But in the case of an airplane, the shockwave is far more intense and louder because it’s caused by a large, fast-moving aircraft.
A Strong Thunderclap
When the aircraft eventually punches through all those piled-up sound waves, they get released all at once, producing what sounds like a loud clap of thunder. This is the familiar sonic boom that is so commonly talked about. It’s like the airplane declaring, “Hey, look at me, I just broke through the sound barrier.” The boom quickly settles down to the ground, and anyone standing there hears it as a sudden, loud bang or sharp noise. Some liken it to a strong thunderclap or a big explosion.
Shakes the Ground Beneath Your Feet
A sonic boom can be unnerving, surprising, and startling because it comes out of what seems to be nowhere. It is much louder and sharper than the usual sounds produced by aircraft in flight. You can feel it permeate your entire body. It’s almost as if someone suddenly slammed a door very close to you when you least expect it. Some people report the experience as being like a sharp crack or an abruptly loud rumble that shakes the ground beneath their feet.
A Ban on Supersonic Flight Over Land Masses
Having these loud bangs happen continuously throughout the day over residential homes and businesses would not sit well with the public. That is why the FAA (Federal Aviation Administration) long ago banned supersonic flight over land masses. This ban has limited passenger air travel to subsonic flights unless an aircraft is over large international bodies of water. During the days of the SST or Concord, the speed of sound would not be exceeded until the aircraft was out over the Atlantic Ocean, where few, if any, would hear the sonic boom.
Faster and More Efficient Travel Internationally
The development of the X-59 could be a paradigm shift in this regard, allowing faster and more efficient travel internationally and domestically. Most modern commercial aircraft travel at about 80 percent of the speed of sound. This has long limited high-altitude aircraft to travel at best, at around 550 miles per hour. When the speed of sound no longer limits an aircraft, we could expect speeds to be on the order of 1.6 times the speed of sound or greater. That translates to easily over 1000 miles per hour.
Los Angeles To New York
Traveling at these new speeds could make commercial flights much more convenient. For example, with conventional commercial passenger aircraft, it takes about five hours to fly from Los Angeles to New York. What if that same flight could be accomplished in perhaps just over two hours? Less time en route also means greater passenger comfort, less air traffic congestion, and improved overall airplane utilization.
NASA’s Final Flight Testing in Late 2024
The Lockheed Martin X-59 Quesst, or Super Quite SuperSonic Technology, is an experimental aircraft project under development by Skunk Works for NASA’s Low-Boom Flight Demonstrator initiative. The program was first introduced in early 2016, with late-stage X-59 flight testing currently underway. After delays this year (2024), it is on track for NASA’s final flight testing in late 2024. It is projected to have a normal cruise speed of around Mach 1.42 or about 900 mph at an altitude of 55,000 ft, creating a low-impact noise level type thump as opposed to the typical violently loud sonic boom. The main objective is to evaluate the viability of this innovative supersonic transport in future passenger service.
Updated
Stay tuned, as your next domestic or international flight may soon be noticeably faster. You can follow the progress of the X-59 an and QUESST project on their respective websites.
X-59 YouTube Video: The First Look At The Future of Supersonic Flight: X-59 Rollout
QUESST YouTube Video: How NASA’s X-59 May Change the Future of High-Speed Flight