# Breaking the "sound barrier" without an engine

I read that a person in the early '60’s might have exceeded the speed of sound as the result of parachuting out of a balloon at 100,000 feet.

The balloon just definitely happened, but is there credible evidence that he might have zipped past the speed of sound at one point in his descent?

Listen closely, children – I’m doing my famous “talking out of my ass” trick. In other words, check my facts, but my reasoning is sound (no pun intended).

The terminal velocity of the average human body is about 120-150 miles per hour at or below 10,000 feet, a bit faster at greater altitude where there’s less air resistance.

The speed of sound (Mach 1) is about 750 miles per hour at sea level, decreasing by some small or fractional percentage every thousand feet.

If the plummeting parachutist in the OP did in fact technically pass Mach 1, he did it way-high up, and it was not something to be impressed by. He was going much slower than a speeding bullet or the business end of a whip.

–Da Cap’n

Well, that wouldn’t be the way to do it. You soon reach maximum velocity - I believe the term is “terminal velocity” - where you do not speed up anymore. You reach this fairly quickly upon the beginning of your descent. And it is far slower than the speed of sound, I believe…

Yer pal,
Satan

Well, what’s four minutes between friends, Captain?

Yer pal,
Satan

Also, this guy’s supposedly whizzing along at Mach 1 and then suddenly deploys a parachute?

That’d have to be one helluva strong 'chute, no?

Back off, man. I’m a scientist.

Um, make that “The balloon jump definitely happened.”

I was aware of all this. The question was not did he fall at 700+ mph, but did he exceed the speed of sound.

[quote}Also, this guy’s supposedly whizzing along at Mach 1 and then suddenly deploys a parachute?[/quote]

No, and this was not indicated in the OP.

So then he hit the ground at Mach 1?

Back off, man. I’m a scientist.

I think everyone’s missing the big picture here. A jump from 100,000 feet? He would have died from High Altitude Pulmonary Edima or HAPE for short. This is why people go looney and die while climbing Mount Everest which is only 29,000 feet, and where the climbers have had time to acclimitize. There’s no way this guy even survived to jump from the balloon.

Not that his has anything to do with the original post, but in answer to the question, you don’t need an engine to break the sound barrier. All you need is a whip.

IIRC, the “Guinness Book” said that he might have exceeded the speed of sound.

I did find a link on the story, and the write doesn’t claim to have exceeded the speed of sound, just to have come close:

But is the info in this link plausible?

WIGGUM
High-altitude parachutists routinely use oxygen tanks to keep from suffocating on the way down. He was probably breathing bottled oxygen in the balloon (and on the ground, before ascent, according to the link).

Nothing I write about any person or group should be applied to a larger group.

Part of this question hinges on what is the speed of sound at 100,000 feet. The other part hinges on what is the terminal velocity of a person at 100,000 feet.

The answer to the first is hinted at: http://www.allstar.fiu.edu/aero/mach.htm

The speed of sound declines to about 86% of its sea-level value between 37,000 and 60,000 feet. What it does above that I don’t know, since the temperature keeps rising at the top of the statosphere until it reaches about 0 degrees Fahrenheit. The pressure, of course decreases.

Anyway, my WAG is that the speed of sound at this altitude is about 600 mph.

http://www.straightdope.com/ubb/Forum3/HTML/002399.html

Above 60,000 feet, up to 100,000 feet is an interval of 40,000 feet. A falling object will cover that distance in a vacuum in 50 seconds (16T^2=40,000 therefore t=50), attaining a terminal velocity of 80,000 feet per second. (More than 54,000 miles per hour)

Absurd, of course. But the magnitude of the velocity does allow for the question of whether or not the now trivial speed of 700 miles per hour could be achieved before the thickness of atmosphere intervened.

Compression of the air below the falling object will exert a force varying directly with the rate of descent. The magnitude of that force is also variable with the shape, and density of the object, and the pressure, and temperature of the air. Even at the extreme altitude of 100,000 feet there is some air, and it has some resistance to offer a falling object. The object need fall only six hundred or so feet to break the sound barrier on the surface, if it followed the curve for objects falling in a vacuum. However, the force opposing the acceleration increases at the same geometric rate as the speed, until it becomes equilibrium. As the object falls, it also enters a steeply increasing density of air over distance. However quickly the object reaches its terminal velocity in the low-density medium, it cannot exceed that velocity, and the magnitude of the terminal velocity decreases as the altitude decreases.

I do not have figures for the specific problem, however, the upper atmosphere of the Earth does not drop off in a uniform manner, throughout the world, or at all times in any area. The Tropopause extends upward to 70,000 feet at times, or less, and the abruptness of the demarcation is not constant, either. Finding out the answer for a particular object would require information for the day, time, location, and weather conditions, the size, position in flight, weight, surface materials of clothing, and a huge other list of variables. Hence, I imagine the guarded statement that someone might have gone faster than the speed of sound. I think it unlikely.

<p align=“center”>Tris</p>

The balloon jump really happened. The person who did it was Joe Kittinger, who’s still alive and kicking. He had to wear a full pressure suit for the ascent (the partial pressure is so low at that altitude that an oxygen mask won’t cut it - your membranes wouldn’t absorb the oxygen).

I believe he hit speeds very close to Mach 1, or absolute speeds somewhere near 500 mph. Terminal velocity depends on air density, the flat plate drag of the thing falling, and its mass. In Kittinger’s case, the air was very thin, and he was wearing a lot of heavy gear.

The balloon jump did happen and he did in fact BREAK the sound barrier. He deployed a drag chute to slow his fall before he deployed his main chute.

GasDr, have you got a cite that proves that statement? If not, we’ll all just assume you pulled it out of your ass. Have a nice day.

There was a great documentary on it on the Discovery Channel about a month or so ago. The jump, or at least part of it, was filmed.
What’s in my ass tends to come out naturally i.e. no pulling required.