Sounding out the sonic boom record

04 June 2019

Interview with 

Adam Murphy

SONIC-BOOM

Plane creating a sonic boom

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This is the part of the show where we usually tackle your questions for Question of the week, but as it’s extreme month, we’re bringing you an extreme record of the week - and no that’s nothing to do with avant garde music. Here’s Adam Murphy to sound out the sonic boom…

Adam - One of humanity’s first extremes of speed was to travel faster than sound (which is 767 miles per hour in air). So when did we accomplish it. The 19th century? 20th?

Well, the first human made invention to break the speed of sound is likely thousands of years old. That sound a whip makes when it cracks, that’s a sonic boom, a telltale noise that signals supersonic speeds.

But when did a human first push past the sound barrier. During World War Two there are lots of unconfirmed reports of fighter pilots doing it, as they pushed their planes to the limit. But most of these are probably just misreading the instruments.

It’s a hard thing to do, travel that fast. As you push up against the sound barrier, the sound waves your plane is making are all bunched up alongside the plane, they’re not travelling off ahead of you. All those sound waves bunched together make a shock wave, with messes with any plane you might be flying.

In October of 1947, an American plane, the Bell X-1, with Chuck Jaeger in the cockpit, was the first confirmed super sonic flight. The Bell X-1 had a load of special design quirks. A pointy nose, which could cut through the air better than a round one, and shorter wings, to lower the risk of damage due to a shockwave.

Once we learned what was going on at that speed, we got pretty good at breaking it. Fighter pilots in the 50s did it routinely, and we even had a supersonic passenger jet, Concorde in the 90s.

Only one land vehicle has ever broken the sound barrier, the Thrust SSC. It looks like a missile with wheels that has two jet engines strapped to it. In 1997 It broke the sound barrier in a flat bit of desert in Jordan.

But we can go more extreme than that. A human has broken the sound barrier, all by themselves.

In 2012, Felix Baumgartner jumped out of a helium balloon, 24 miles up. As he was falling, before he opened his parachute, Baumgarnter travelled fast enough to break the sound barrier, without being in any kind of vehicle.

Which is pretty extreme.

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