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Sub-Orbital Skydiving
igz writes: "Someone is trying to set the world record for highest freefall, from over 31 miles above the Earth! There is no atmosphere up there, so speeds of up to 1.5 Mach are expected. Check it here." Whether this is insanity or courage is up to you, but it sure sounds like a fun ride. Cheryl Stearns is the insane / courageous diver, and she will jump wearing a pressure suit to counter the lack of air at (gulp!)165,000 feet up.
A simulation of the Kittinger dive is on the NOVA website. Plus they also show the famous picture of him jumping out of the gondola.
Also there is a really great book written by Craig Ryan called The Pre-Astronauts. The Pre-Astronauts is all about the history of high altitude skydiving. A cool quote by Alan Shepard from the book when asked if he would have done the Kittinger jump: "Hell no. Absolutely not."
Another cool fact is that Capt. Kittinger's boss during those high skyjumps was no other than John Paul Stapp the guy who is always in those famous pictures and movies of the rocket sled. Remember those pictures of a man's face being progressively made more distorted by g-forces? That's John Paul Stapp!
"sweet dreams are made of this..."
Mach 1.5? Everyone knows that to travel in time you need to be going 88 Mph!
Now how is she going to generate the 1.21 gigawatts of electricity?
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Why can't I moderate something "Wrong" or at least "Grossly Misinformed"?
However, in the interests of science, I think she should take the risk of shouting it briefly just before reaching Mach 1, so she can be able to hear herself going "oooooooominoreG" shortly after.
A pizza of radius z and thickness a has a volume of pi z z a
Pressurized suit: $20,000
Extremely high altitude flight: $15,000
Used parachute: $40
Patches for parachute: $5.37
Becoming the biggest Jackson Pollack painting ever: priceless.
At what point do you need to stop worrying about oxygen, so much as worrying about re-entry friction?
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Hey! You were wrong, the cat dies too. (And boy is my wife PISSED at me now!)
- "When I say dance, you'd best DANCE motherf*cker!" -Violent Femmes
It isn't actually outside the atmosphere, there is just very little air. You use huge balloons - have a look at Lindstrand Balloons, they do lots of pioneering stuff like the ballooning equivalent of satelites and heavy lift airships. Actually, there is a very good chance that they will make this balloon. Either them or Cameron Balloons.
This would be an amazin accomplishment, but it should be noted that this would not be the first dive from an altitude high enough to require a pressure suit. Forty years ago Joseph Kittinger made a succesfull jump from 103,000'. A quick google search turned up some sites with info on him and his jump. Check some of them out:
Here
and
Hereand
HereDan
Pressurized suit: $20,000
Extremely high altitude flight: $15,000
Used parachute: $40
Patches for parachute: $5.37
Being the first person to achievesubterranean supersonic travel: priceless.
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Several Million, B.C: great lizards known as "Dino-saurs" were rendered extinct by the impact of a meteorite off the Yucatan.
2000: Parachutist Cheryl Stearns achieves the first sub-orbital skydive, with mixed results. When she reached Mach 1.5, Cheryl vanished, never to be seen again.
2020: It has been determined that Cheryl Stearns, upon breaking mach 1.5, travelled through time, and smashed into the Yucatan. The resulting clouds and debris led to the extinction of all dinosaurs.
Not quite -- due to decreasing air temperature, the speed of sound actually decreases as you go up for a while, then increases again until you hit near-vacuum.
- Sea level -- 1116 fps
- 36000 to 82000 feet -- 968 fps
- 150000 feet -- 1075 fps
- 250000 feet and up -- by a quirk of physics, 1116 fps again!
NASA has a nice web tutorial on this topic. Greg Roth has a more precise javascript calculator.Wow, that's fast... I was under the impression that breaking the sound barrier was rather stressful for whatever does it, since the sound waves it creates can't get out of its way before it plows into them. I guess a lone parachuter may not be making much sound, especially until she hits the atmosphere, but once she does reach air it seems to me that the amount of drag on her body would amplify greatly due to the high speeds and the effect of the sound barrier. If the sound barrier can tear the wings off of airplanes, I wonder how she plans to prevent, say, her head from being torn from her neck?
Of course, I Am Not A Physicist, so please don't flame me if I sound stupid. =-)
Wow, that's fast... I was under the impression that breaking the sound barrier was rather stressful for whatever does it, since the sound waves it creates can't get out of its way before it plows into them. I guess a lone parachuter may not be making much sound, especially until she hits the atmosphere, but once she does reach air it seems to me that the amount of drag on her body would amplify greatly due to the high speeds and the effect of the sound barrier.
The speed Mach 1.5 is a little misleading - in the air she'll be travelling through, she won't be breaking the speed of sound, although she may reach around 1000 miles/hour. In thin air, the speed of sound is much higher than at sea level. She will actually decelerate as she falls into the thicker lower atmosphere, so at no time will she be going fast than the speed of sound in the air she is travelling through. The main danger as far as I can see is difficulty in preventing a spin in a thin atmosphere - there is little air resistance to allow you to stop rotation motion. Still, for an experienced sky diver, this shouldn't be an insurmountable problem.
Cheers,
Toby Haynes
Anything I post is strictly my own thoughts and doesn't necessarily have anything to do with the opinions of IBM.
You think that's wacky? In the early 60's, there were a number of designs for a single-person bailout device, for "bailing out" from *orbit*. MOOSE was one such design, where the astronaut was enclosed in a foam shield.
:)
Mach 1.5, bah! Try Mach *25*!
Why does it matter if she is single or married?
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This is a good example of where it pays to read the linked article. In this case the article mentions that burnup on re-entry is caused by the speeds necessary for orbit. With entry of asteroids it is the speed that got them to earth that is the problem. Since she will be starting at a stable speed relative to the earth, and her only speed will be that due to gravity, she won't have any real friction/heat problems.
Re-entry friction is less of a problem if you drop straight down. Something in orbit has a very large horizontal velocity (too lazy to work out the numbers, but roughly the circumference of the earth in 90 minutes), and much of the heat of re-entry is caused by this horizontal velocity.
According to the article she'll only get up to Mach 1.5 [doesn't say if that's relative to the speed of sound at sea level, or to the actual speed of sound in the air she's passing through], and that's quite a bit less then orbital velocity.
How, exactly, does one get a balloon to float outside of the Earth's atmosphere?
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Re-entry friction is less of a problem if you drop straight down. Something in orbit has a very large horizontal velocity (too lazy to work out the numbers, but roughly the circumference of the earth in 90 minutes), and much of the heat of re-entry is caused by this horizontal velocity.
Orbital velocity is about 8 km/second (5 miles/second).
Energy shed into the atmosphere is roughly proprortional to the cube of the velocity, so something travelling at Mach 1.5 (about 0.5 km/second) sheds about 4000 times less energy per unit time (and generates 4000 times less heat).
Summary: Quite a bit slower, and *much* less heat generation.
The problem here isn't so much traveling at Mach 1.5 (I'm sure the pressure suit is well insulated and heat resitant to avoid the cold and the heat) but its the point where she breaks the sound barrier. After that, it should be smooth sailing, since she's passed her own shockwave. However, I still do not belive this will be a considerable problem. remeber, an airplane is many many times more massive than a human being. It will generate a much much more powerful shockwave which it will then have to overcome once it approaches the speed of sound. A single human woman isn't going to have this problem. In addition, remeber, surface area for objects is typically a in a higher ratio to mass for less massive objects (i.e humans) than massive objects (i.e. jet aircraft). For a simple experiment in this, throw an ant, a cat, yourself, and a horse down a 100ft mine shaft. The ant is going to hit the ground with little to no damage. The cat may break a leg or too, but will live. You will more likely than not die. The horse will splatter. Same thing applies to the drag forces about the fusalage of a plane and about this woman. Its going to be relatively much less for the woman.
Surely there's someone here who can give us an estimate of how long it would take?
The previous world record was 102800 feet, set by Captain Joseph Kittinger in 1960. IIRC, he freefell for between four and four-and-a-half minutes, and pulled at an unusually high altitude (20000' or thereabouts). So it follows that a freefall from 160000' would probably take in the neighborhood of 7-8 minutes.
Yes, I am a skydiver.
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We're all under the illusion that there is a such thing as perpetual freefall. 31 miles up! That's going to add some freefall time to your log book! Let's see. My charts stop at 15k feet. Assuming you open at 2500 ft, that's somewhere around 75 seconds of freefall, through approximately 2.5 miles of very thick air. I wonder how long this jump will last?
I'm sure that the danger that they refer to is related to the thinness of the air. Without air blowing by you, you can't control which way your body is turning. If you can't control that, then you can't prevent a spin. That would be bad.
BTW, Cheryl Stearns is among the elite skygods. She's got a gazillion jumps, and a bunch of style and accuracy championships. She's been a fabulous ambassador to the sport, and should rightfully be credited as one of the sport's most important participants.
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Seems like there's not much left to do after something like this. I suppose some nuts will try to set a new record by having sex while they jump from 31 mi. up.
They started spinning so fast that they broke apart. The air is so thin that there's no damping whatsoever.
thad
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