# Parachuting from 23 miles up.

Damned if I can get my link to work.
Monday some dude is going 120,000 feet (6000 pesos) above ground.
High enough that the claim is he will break the sound barrier.
Going to look for a different link.

Can a person go super-sonic? I thought we had terminal velocity.

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.

This is a good article from Pop Sci. http://www.popsci.com/technology/article/2012-10/supersonic-skydive-science-dangers

Good stuff, thanks.

This could either be the most ass-kicking ride ever, or suicide.

Makes you wonder whether you’d rather burn up or have your blood boil. How quick would it be?

I didn’t see it in that article…how is he going to safely slow down from supersonic speeds to near zero? Just letting out an ordinary parachute would rip it to shreds in seconds and probably set it on fire from the friction.

I assume that as he is falling, the atmosphere will get denser, and terminal velocity will decrease to what it would be for a low-altitude jump. Then open the parachute.

If he’s slowing by atmospheric friction, that’s an awful lot of heat to dissipate, and in a short time span.

The jump has been postponed 24 hours due to a cold front moving through, with gusty winds. The jump is being sponsored by Red Bull; the mission has been dubbed Red Bull Stratos. Here is a link to their website.

The heat from atmospheric friction won’t be too bad (he’ll be in freefall for over 5 minutes). Bigger problems are the effects of depressurization and the extreme cold. He will be wearing a pressurized suit for protection. A breach in the suit could be catastrophic.

Another problem is the thin air. If he can’t control his body in freefall he could go into a spin from which he can’t recover, making deployment difficult to impossible. Or he could black out from the spin. He will have an automatic opener on his reserve parachute should he fail to deploy his main canopy.

He has already performed two practice jumps, the second from 97,000 feet in July.

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).

He definitely was close to the speed of sound, which, between 11,000 and 20,000 m of altitude, is roughly 660 mph. And he had no problem decelerating as he came through denser layers of atmosphere.

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

Kittinger is a living legend to skydivers (I used to jump a lot, not so much these days). In fact, he is an advisor to the Red Bull team and will be in Roswell for the jump- at the age of 84!

Provided he stays conscious, it’s hard to see how an experienced jumper would lose the ability to control his body in freefall.

No air.

A skydiver uses the relative wind to remain stable and move around in the sky. On a normal jump terminal velocity is about 120 mph. That air is flowing past the jumper (relatively speaking) and the jumper uses it to control himself. In a stable belly-to-earth position his knees and elbows are bent at a 90 degree angle. If he straightens his legs, he pushes off the relative wind and moves forward. If he sticks his arms out he moves backward. Stick one arm out to the side and he turns.

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.

The same thing happens when jumping from a hot-air balloon or a hovering helicopter. There is no relative wind until the jumper builds up some speed. The first time I jumped from a helicopter my arms and legs were “windmilling” like crazy, until I built up some speed.

Jumping from an airplane that is in flight is different. I already have some relative wind from the forward speed of the plane. When I exit I arch my back and face into the relative wind. As I transition from going forward to falling straight down I build up speed. The more speed I have, the easier it is to control myself since more air is flowing past me.

From the OP: “Monday some dude is going 120,000 feet (6000 pesos) above ground.”
I’ve never heard of a unit of length called a peso.

Maybe he was thinking of the pace though the math doesn’t work.

You’d have to pay me a helluva lot more than 6k pesos to get me up there. And if this guy buys the farm on camera I would not want to be Red Bull.

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

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.