Sonic booms are always pretty impressive, but they’re not always desired. That’s why NASA is working on supersonic aircraft that don’t make quite so much noise, and you’ll be able to see – well, hear – them conduct some test flights this November if you’re based in Galveston, Texas.
Sometime then, an F/A-18 fighter jet will conduct a series of maneuvers, those designed to create both very loud sonic booms and somewhat more muted ones. This jet isn’t designed to be muffled, but the loudness of the boom can be adjusted depending on how you fly.
The agency will then use feedback from audio sensors and 500 local volunteers to find out how much they heard. By using this data, they’ll then feed it into their sonic boom-killing research program, one that hopes to design supersonic-but-silent planes.
In the following footage, the jet produces both a normal sonic boom, then a "low boom":
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A sonic boom is more than just a loud bang, and it certainly isn’t an explosion in the way you may be thinking. It’s a fluid dynamics thing: When an aircraft traveling through the air – the fluid – moves at increasingly fast speeds, the molecules of air at its nose get increasingly compressed. This is represented as an uptick in localized air pressure.
When traveling at supersonic speeds, those faster than the speed of sound in air, these air molecules are pushed aside with such considerable force that the individual pressure waves merge and form a shockwave. This shockwave moves outward in all directions, and when it reaches your ears, it sounds like a “boom”.