Skydiver To Break Sound Barrier During Free-Fall

Hugh Pickens writes "Over fifty years ago, American Joe Kittinger made history by leaping from a balloon at 102,800 ft, and although many have sought to repeat the feat, all have failed. Now, BBC reports that Austrian extreme sportsman Felix Baumgartner will try to break the long-standing record for the highest ever parachute jump, skydiving from a balloon sent to at least 120,000 ft, and it is likely that 35 seconds into in his long free-fall of more than five minutes, he will exceed the speed of sound — the first person to do so without the aid of a machine. 'No-one really knows what that will be like,' says Baumgartner. Although challenges in the endeavor include coping with freezing temperatures and ultra-thin air, a key objective for Baumgartner will be to try to maintain a good attitude during the descent and prevent his body from going into a spin and blacking out. 'The fact is you have a lot of different airflows coming around your body; and some parts of your body are in supersonic flow and some parts are in transonic flow. What kind of reaction that creates, I can't tell you,' adds Baumgartner."

Comments

Star Trek

[tripmine]

Am I the only one that though of the space diving scene from Star Trek 11?

Just use a dummy first.

[starbugs]

Test the survivability of this by using a dummy with G-force sensors (just like we see on Mythbusters).
Then, if all goes well - try the stunt.

And please, use some kind of stabilizer to make sure you don't turn into a frisbee.

I do see potential in this 'experiment' if anyone ever needs to bail out on spaceship2.

Re:no sound = no sound barrier

[Deadstick]

His potential energy at 120,000 feet would be...ummm, let's see...120,000 foot-pounds per pound of suited-up weight. Tough calculation.

More to the point, let's say he intends to go sonic at 20,000 feet. In falling 100,000 feet he'd reach a speed of 2530 ft/sec if there were no air drag. The speed of sound at that altitude is 1036 ft/sec, so he has a chance, depending on how little drag he can achieve.

As he comes down in altitude, the drag and the speed of sound both go up, so it becomes a much harder calculation. There is an abrupt drag rise right around Mach 1, so there's a significant chance he could stabilize at, say, Mach 0.98 and be unable to accelerate further.

rj

Physics novice, here:

[captainskyhawk]

Isn't "terminal velocity" lower than the speed of sound?

Re:Physics novice, here:

[WittyName]

The speed of sound depends on the density of the air. Your acceleration would also be affected, drag is at a cube rate or fourth?!? rate. Gravity depends on the distance from the center of the earth. Without doing the math, there should be some region where resistance is low, acceleration fairly high, allowing supersonic speed.

Some body armor, perhaps a viscous gel embedded with carbon fiber, seems wise! Maybe a helmet to keep facial features from being torn removed.. Frost burn, too.

Drift?

[RevWaldo]

During the fall, how far could he drift from the balloon's overhead position? A few miles? Tens of miles?

Re:A simple machine

[Anubis IV]

Not true at all. He wants to exceed the speed of sound by falling quickly, but the dang balloon keeps lifting him up! If anything, it's actively working against him!

On a more serious note, which simple machines would you say make up a balloon? Is it a pulley? A wedge? A lever? A balloon is just hot air in a sack. Nothing machine-like about that, though I suppose the mechanism for generating hot air may involve a machine, but that's tangential.

Re:What ever happened to Terminal Velocity?

[barzok]

Except he won't be at 120,000 feet when he reaches 300 m/s, he's going to fall from that altitude.

The question is will his velocity at any point during the descent be greater than the speed of sound; given that the speed of sound will be increasing while his terminal velocity will be decreasing, what you need to find the the point at which the two curves cross.