The goal is to confirm the theory that a 75-decibel boom will be acceptable. Once the X-59 is flown over the selected areas, NASA will engage with the communities on the ground to gauge their response to the noise. “Only when we’re satisfied with the performance we’ll go out to the communities, and still carefully control the level of the sonic booms.” “We don’t want to repeat that, of course, that’s why we’re going to test this aircraft on a restricted range first, measuring all the booms,” says Nickol. It didn’t go well, with up to 20% of people objecting to the booms and 4% filing complaints and damage claims. The plan is reminiscent of an experiment run by the Federal Aviation Administration (FAA) in 1964, when supersonic fighter jets were repeatedly flown over Oklahoma City to test the impact of sonic booms on the public. The crucial part of the program will start in 2024, when a series of test flights will be performed over half a dozen residential communities across the US, selected to offer a diverse mix of geographic and atmospheric conditions: “That’s going to be a fun part of the project, because we’re going to engage with the public and generate a little bit of citizen science,” says Nickol. “It may even be that people don’t hear the boom at all, and if they do they will certainly not be startled, because it will be low and spread out, and not that loud at all.” ![]() “What that means is that this aircraft may sound like distant thunder on the horizon, or like someone shutting a car door around the corner,” Nickol says. The lone engine is also at the top rather than the bottom of the plane, to keep a smooth lower profile that prevents shockwaves from reaching the ground.Īs a result, NASA believes the X-59 will produce just 75 decibels of sound when traveling at supersonic speeds, compared to Concorde’s 105 decibels. Instead, they spread out, with the help of strategically placed aerodynamic surfaces. The X-59’s shape is designed to prevent the shockwaves from coalescing together. ![]() When this highly compressed shockwave meets a human ear, it produces a loud boom, which does not occur when the plane breaks the sound barrier, but is rather a continuous effect that can be heard by anyone in a cone-shaped area beneath the plane, as long as it exceeds the speed of sound. Lockheed Martinīut how does a sonic boom happen? When an aircraft travels at subsonic speeds, the sound waves that it normally creates can travel in all directions at supersonic speeds, however, the aircraft will leave its own sound behind and the sound waves will compress and coalesce into a single shockwave that originates at the nose and ends at the tail. The sleek shape plays a key role in making the aircraft much quieter when traveling supersonically. The nose is a distinguishing feature on this aircraft: it’s about a third of the length.” “It’s extremely long and thin: It’s almost 100 feet long (30.5 meters), but has a wingspan of only about 29 feet. ![]() “It will be significantly quieter than Concorde or any other supersonic aircraft that exist today,” says Craig Nickol, senior adviser at NASA Headquarters. The X-59 is the latest in a series of experimental planes which include the X-1, which in 1947 became the first manned aircraft to exceed the speed of sound, and the X-15, which still holds the record for the fastest ever manned flight, set in 1967 at Mach 6.7.ĭesigned and built by Lockheed Martin in Palmdale, California, under a $247.5 million NASA contract, the X-59 is currently undergoing tests on the ground, in anticipation of a first flight later in 2022. The agency is doing so through a program called Quesst, which is the result of decades of research and is centered around a new aircraft called the X-59. Now, NASA is working to change those regulations by transforming the boom into a “thump,” paving the way for a new generation of quieter supersonic aircraft. The supersonic airliner was restricted to subsonic speeds when flying over land or near coastlines, and current international regulations still limit the speed of commercial transport over land to below Mach 1, or the speed of sound, to avoid the disturbance of sonic booms over inhabited areas. Sonic booms are part of the reason why there are no supersonic passenger planes flying today, and one of the limiting factors to the success of Concorde, which last flew in 2003. The loud, explosion-like bang – caused by a plane flying faster than the speed of sound – can be startling, and even crack windows. If you’ve heard a sonic boom recently, you probably remember it.
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