Parachuting from 23 miles up.

[Musicat]

@Szlater

He’s not re-entering from orbit and decelerating from many 1000’s of miles per hour, he’s maybe travelling at Mach 1.

You say that as if Mach 1 is what my bicycle does downhill with a tailwind.

[Szlater]

@Musicat

You say that as if Mach 1 is what my bicycle does downhill with a tailwind.

It’s just not that fast, you can build a car to go faster than that at sea level.

[jayjay]

@JoseB

I am surprised that people here have not mentioned Joseph Kittinger yet, holder of the highest parachute jump of all times, on August 16, 1960, from a balloon at 102,800 feet (31,300 m). Of course with a pressurized suit. From the Wikipedia article:

Towing a small drogue parachute for initial stabilization, he fell for four minutes and 36 seconds, reaching a maximum speed of 614 miles per hour (988 km/h) before opening his parachute at 18,000 feet (5,500 m). Pressurization for his right glove malfunctioned during the ascent, and his right hand swelled up to twice its normal size. He set historical numbers for highest balloon ascent, highest parachute jump, longest drogue-fall (four minutes), and fastest speed by a human being through the atmosphere. These are still current USAF records, but were not submitted for aerospace world records to the Fédération Aéronautique Internationale (FAI).

So the answer to the question “Has anyone ever skydived 102,000 feet?” is “Just once, for 4 1/2 minutes, in 1960”?

[Hari_Seldon]

@robby

Terminal velocity is dependent on the density of the air. If someone free-falls from high enough, their terminal velocity could well be supersonic.

As the person continues to fall to the Earth and the air gets more dense, their terminal velocity will steadily decrease.

Speed of sound also increases with decreasing pressure. Maybe not enough.

[Lukeinva]

Parachuting from 23 miles up…

That’s high.

[gaffa]

@JoseB

Born in 1928, Joseph Kittinger is still alive, btw.

That is because death is afraid of him.

[AaronX]

@Szlater

He’s not re-entering from orbit and decelerating from many 1000’s of miles per hour, he’s maybe travelling at Mach 1.

As for the parachute, there are supersonic rated parachutes, no human has used one but there are parachutes that will survive deployment at supersonic speeds.

Maybe it would have been easier to build him a backpack that hovered above the ground and lowered him on cables, then flew away?

[Malacandra]

@Musicat

You say that as if Mach 1 is what my bicycle does downhill with a tailwind.

He says it as if your kinetic energy (and hence the heat you have to dissipate) at 600mph is about one thousandth of what it would be at 17,000mph (orbital velocity).

@joebuck20

Yeah, company execs will be in the awkward position of having to explain why Red Bull didn’t give him wings.

badum-tissh!

[sparky_1]

Why would anyone jump out of a perfectly good balloon?

[Xema]

@Bumbershoot

At 120,000 feet the air is so thin it provides no resistance at all. It is very difficult to remain stable with no air to push off of.

Once terminal velocity is reached, the force on the jumper is equal to his weight - just as it as at much lower altitudes. He thus has the same kind of control over his position.

[Bumbershoot]

@Xema

Once terminal velocity is reached, the force on the jumper is equal to his weight - just as it as at much lower altitudes. He thus has the same kind of control over his position.

But until he reaches terminal velocity, he has very little to no control. He could go into a rapid spin and black out.

Edit: At 120,000 feet he is essentially in a vacuum. There is no force to balance, no wind resistance.

[kferr]

@Bumbershoot

But until he reaches terminal velocity, he has very little to no control. He could go into a rapid spin and black out.

Edit: At 120,000 feet he is essentially in a vacuum. There is no force to balance, no wind resistance.

If there is no wind resistance then there is no force that could cause a rapid spin.

[Bumbershoot]

@kferr

If there is no wind resistance then there is no force that could cause a rapid spin.

You’re right. “No wind resistance” was a slight exaggeration. There is a little air up there.

Instability on exit could cause tumbling, rolling or spinning with no way to correct it until he gets closer to the ground where the air is thicker.

Felix Baumgartner (the jumper in question) has a drogue chute he can deploy for stability if necessary, as described here:

If Felix becomes unstable, he may need the drogue chute to keep from spinning uncontrollably. However, in his quest to break the sound barrier, he doesn’t want to deploy a drogue unless absolutely necessary, as it could slow him down.

[EvilTOJ]

@Musicat

Just letting out an ordinary parachute would rip it to shreds in seconds and probably set it on fire from the friction.

Add a guitar, and maybe some skulls and this is probably the most metal way to die ever!

[Richard_Pearse]

@Hari_Seldon

Speed of sound also increases with decreasing pressure. Maybe not enough.

It is actually related to temperature. The speed of sound increases with increasing temperature.

[Bumbershoot]

The countdown is on for tomorrow morning. Of course inclement weather could force another delay. They will be streaming the whole thing here. Baumgartner will have a few cameras mounted on his suit so we can watch from his point of view.

I think his odds are pretty good. I don’t think he will actually go into an unrecoverable spin. The only reason I brought it up was in response to an earlier question about heat buildup from atmospheric friction. I said it wouldn’t be a big deal but there were other potential problems, including the possibility of a rapid spin.

Baumgartner is a very experienced skydiver and BASE jumper. The Red Bull Stratos team has been very cautious and deliberate. They’ve been planning this jump for years and have attempted to cover every contingency. They have already made two successful jumps, from 71,000 ft. and 97,000 ft.

Oh, I also entered their “Guess where Felix will land” contest (officially known as the Drop Zone Competition). You can enter on their website.

[Finagle]

@Szlater

It’s just not that fast, you can build a car to go faster than that at sea level.

That’s not a car, that’s a jet plane they didn’t bother putting wings on.

[Lantern]

Felix Baumgartner doesn’t jump to Earth, Earth jumps to Felix Baumgartner.
Just read about this storyon the NYT,

Apparently he had a major problem with claustrophobia:

During five years of training, he started suffering panic attacks when he had to spend hours locked inside the stiff pressurized suit and helmet necessary for survival at the edge of space.

But he persevered with the help of psychological conditioning and a mentor, Joe Kittinger, a retired Air Force colonel who has held the altitude and speed records since 1960, when he jumped 19 miles from a balloon during a research project (after nearly dying in a practice jump). Mr. Kittinger, now 84, will be the only voice on the radio guiding Mr. Baumgartner during the two-hour ascent to the stratosphere.

And if he doesn’t jump right he could be in serious trouble:

The Red Bull helium balloon is supposed to climb more than 120,000 feet. There, Mr. Baumgartner will perform an exquisitely rehearsed bunny hop designed to keep his body from spinning out of control.

“In a regular sky-dive, you use your hands against the air to stop from tumbling, but there’s no air to use up there,” he said. “If you start to tumble over, you carry that tumble all the way down.”

The worst-case outcome is the kind of spinning that nearly killed Mr. Kittinger during a training jump in 1959. He went into a flat spin, blacking out as his body whirled at 120 revolutions per minute. He regained consciousness only after his emergency parachute opened automatically.

[Bumbershoot]

Thanks for posting that, Lantern. It pretty well confirms what I’ve been saying all along.

That “bunny hop” is where Baumgartner’s BASE jumping experience comes in. BASE jumping (and jumping from a hot-air balloon or helicopter as I described earlier) has something in common with the space jump. There is no relative wind to use for control. Baumgartner wants to exit head high and slowly transition to a belly-to-earth position.

He does not want to dive out in a head-down position, even slightly. With no air to stop him, his momentum would cause him to flip over. At most he wants his body at a 45 degree angle on exit.

He will be doing his best imitation of a badminton birdie, arching his back to keep his center of gravity low. His arms and legs will act like the feathers giving him whatever stability he can gain.

[AaronX]

Felix Baumgartner's 23-Mile-High Skydive LIVE | Popular Science They’ve begun unpacking the balloon! The balloon can’t be repacked, so looks like this is go.