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Supersonic Skydiver

835 Views 27 Replies 10 Participants Last post by  Soopahmahn
Skydiver preparing for 120,000-foot supersonic fall -

Anyone want to speculate on the physical effects of breaking the sound barrier on a human? I'm not entirely sure I understand what happens - the sound waves of your passing are in essence building up behind your axis of flight right? So isn't it dangerous to come back from supersonic? Depending on the altitude at which crossing that threshold occurs, there would be more or less pressure built up behind you, so I could see that wreaking havoc with his parachute or maybe tossing him around a bit extra?

Kudos to Red Bull too :yesway:
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Without getting silly and actually trying to calculate this, I know there is a shape factor involved in the drag coefficient. We could probably assume he'll present a roughly circular cross-section, but hey, he could be a Canadian with a square body.

Won't the terminal velocity be higher if there isn't as much atmospheric pressure at the higher altitudes? I think we'd have to set up a system of equations to compare the pull of gravity increasing with the inverse square of his distance to the Earth's core vs. the increase of resistance from the atmosphere as he plummets toward sea level pressure. Plus there's water in the air.

But I'm wasting time at work as it is, so why would I try to do that when it's much harder than the work I'm avoiding...? :rofl:
If I had to guess, I'd suggest he's breaking mach1 outside of the atmosphere. When he re-enters he'd slow down to terminal velocity, the parachute will be opening in the same conditions a regular parachute opens, won't it?
Terminal velocity is the asymptotic maximum speed in a given set of conditions at which a body will travel - so when falling through the atmosphere, you assume a constant gravitational pull and a constant air medium etc. You wouldn't say he slowed down to terminal. So he will probably reach and maintain terminal velocity at some point, but the terminal velocity will change as he falls. And since I'm going to assume he'll be traveling faster than "ground terminal", he will slow down, but he may be going much faster than usual when he gets there.

Does anyone think returning from supersonic will cause him to get hit from above with the sound of his own passing?
Call me a pussy, but you couldn't even get me to do that drunk.
Drunk plus 20 bucks. Go.
Well, I'm no physics expert, but as I understand terminal velocity is the point where gravitational acceleration is exactly balanced by atmospheric drag, right? So, I would think if you hit the atmosphere with enough initial speed, as the drag ramped up, it would start to decelerate you (and as it's proportional to your speed it would probably do so faster), but I don't know if the increased drag against momentum would be enough for an instantaneous adjustment, or if it would gradually begin to slow you down to terminal velocity, but for a while you would be at a higher speed than you would otherwise be.

If the later, then yeah, it could make a difference...
Yeah I mean the latter scenario. It depends on how quickly the atmosphere ramps up vs. the gravity pull strengthening (the atmosphere is probably the dominant force).

But it also depends on when he pulls the chute. His terminal velocity, I expect, is way over the speed of sound for a period of time. I suppose the smart thing to do is not to pull the parachute over Mach speed.

Noodles, I'm in too. Let's drag Drew out with a few shots of Macallan in him. Right after we convince someone to fly us up there. :fawk: And we wait to see whether this guy makes it...
The increase in gravity pull in nearly negligible. Gravity is 9.81 m/s^2 on the surface of the earth, and 9.71 m/s^2 at 120,000 feet. That's about a 1% change over the course of the entire fall.
That's what I said :lol:
Well, you said it's probably dominant. I'm saying it's definitely dominant. :hsquid:
:tip of the hat:
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