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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."
It's really going to hurt.
"The average reporter we talk to is 27 years old......They literally know nothing." - Ben Rhodes
If there's enough atmosphere to lift a balloon, there's enough atmosphere to transmit sound.
And the balloon would also be the machine he is 'not getting aid from.' he will exceed the speed of sound — the first person to do so without the aid of a machine. (from the /. story)
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Right, a balloon is not a machine. Way to be redundant.
Meh, it's a question of technicalities. Gravity is the force that will cause him to break the sound barrier (and perhaps the thin air - lack of resistance). A machine will not be used to accelerate him. It will give him tremendous potential energy, however. Anybody want to calculate that?
You can fail to get the balloon to 102,800 ft.
The Tao of math: The numbers you can count are not the real numbers.
he will exceed the speed of sound — the first person to do so without the aid of a machine.
He's using a machine. It's a balloon that sends him up 120,000 ft.
You could also fail to survive the attempt.
Not just that, but undoubtedly he'll have a suit to keep him from freezing and an oxygen supply to keep him from passing out. So if you want to be pedantic, he has plenty of 'machines' aiding him, but nothing with a motor, which I think was the point.
I'm going to guess that he doesn't break the sound barrier. The term "barrier" isn't entirely fanciful, as power required to go faster increases enormously as you approach it.
On the other hand, if he DOES break the sound barrier, I'm going to bet it does him some injury.
He shouldn't feel more than 1 G pushing back on him. I know I abused units, but it's no more force than the ground pushing back on you. Newton's 3rd law. Terminal velocity means acceleration of gravity = -acceleration due to resistance. Otherwise, as long as he doesn't go very far past TV, he shouldn't have to worry too much in that regard (With or without all the other problems). Friction and heat? I don't know how bad that'll be, I hope he does the math before cooking like an egg. If he does cook, that is.
I read TFA and all I got was this lousy cookie
I realize that Terminal Velocity will be higher with less air density, and the speed of sound should be lower, but do they both change so much that this is actually possible?
Guns don't kill people; Physics kills people! - John Lithgow as Dick Solomon on Third Rock From The Sun
You can fail to get the joke.
What can possibly go wrong?? /. memo
Paul Atreides: They tried and failed?
Reverend Mother Mohiam: They tried and died.
Then I guess you better make damn sure you read all your NOTAM's aye bunky?
Yeah I am a pilot.
Hey KID! Yeah you, get the fuck off my lawn!
Air becomes incompressible at supersonic speeds
No it's the opposite, it becomes compressible at supersonic speeds. Low speed airflows are incompressible.
Interviewer: "Is that your crash helmet?"
Jose' Jimenez: " . . . oh I hope not."
Using:
standard atmosphere http://www.desktopaero.com/stdatm.html
Mach/altitude tables http://www.aerospaceweb.org/question/atmosphere/q0112.shtml
g acceleration http://en.wikipedia.org/wiki/Terminal_velocity
and historical stuff on Col Joe.
At 35 seconds he'll have fallen from 120kft to 80kft, going 1126 ft/s. That's Mach 1 at sea level. At 80kft it's Mach 1.15, giving some room for drag error. 10 seconds later he'd cross from stratosphere to tropopause where Mach 1 is lowest, but since it's only a matter of ~6 ft/s, this just gives him room to fall farther if need be but not required. At 80kft the dynamic pressure will be around 55 lb/ft^2, so if fully loaded he weighs more than 165 lbs he'll still accelerate some, but not after the 45 second mark. If he's outfitted like Kittenger was, he'll weigh up towards 300 lbs, and would still accelerate for some time.
At 30 seconds he'll be falling at 965 ft/s, or Mach 0.98, well within the narrow transonic region of highest pressure, "max Q". This is where aircraft prior to the Bell X-1 came apart due to the buffeting of turbulence combined with the growing bow shock pressure wave.
He can do it theoretically. The altitude is just about perfect for the attempt. I'm more concerned about whether he'll be able to keep from getting the piss kicked out of him at the Mach line. Sure, it'll be slight compared to what General Chuck punched through, but he's a damn sight slighter than the X-1. On the other hand Kittenger hit Mach 0.96 around 60kft and I see no report of this effect so maybe it's not a problem.
It may still be a problem to punch through though. There's a spike in the speed/drag curve that's greater or lesser depending on the drag characteristics (coefficient of drag of cD). If his outfit will be shaped to approximate a low cD body so much the better. Since he'll require some form of protection I doubt anyone would fault him for choosing a shape to fit his flight profile.
If he kept up his falling profile he's still slow to terminal velocity for the lower altitude, around 200 MPH, slower still if he's either braking or blacked out and spinning. Lower altitude here is taken to be where he could pop the chute and stay conscious even if he lost his mask, around 20 kft. At that altitude and speed a full open would be quite a jerk, but no more than airborne troops practice, and which I'm sure he's handled previously. If he's designing his chute to be able to be opened higher/faster should he need or want to, he'll include a drogue chute with a delay before the main, to slow him gradually to safe opening speed (especially helpful if spinning).
"I may be synthetic, but I'm not stupid." -- Bishop 341-B