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Old 02-07-12, 01:13 AM   #1
Sailor Steve
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Quote:
Originally Posted by Krauter View Post
I wonder, how do parachutes resist the "impact" of drastically slowing a man at terminal velocity when he opens his canopy?
Here's the perfect explanation to that question, and it ties in perfectly with the current topic.
http://hypertextbook.com/facts/JianHuang.shtml
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Old 02-07-12, 02:13 AM   #2
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I wonder, how do parachutes resist the "impact" of drastically slowing a man at terminal velocity when he opens his canopy?
I wonder with the higher start and the lower deployment, how severe is that impact coing to be?
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Old 02-07-12, 06:42 AM   #3
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Surely he is going to use a multiple stage parachute like Kettinger did
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Old 02-07-12, 08:26 AM   #4
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Originally Posted by Tribesman View Post
I wonder with the higher start and the lower deployment, how severe is that impact coing to be?
He'll actually slow down as he descends into the thicker atmosphere.
By the time his chute deploys, he'll be going no faster than if he'd jumped from an airplane.

The multiple drogue chutes Kittinger used were not to slow the descent, a very common misperception, but to eliminate the chance of a blackout inducing spin. He almost died during a test jump in '59 from such a spin.

From everything I've read, Baumgartner thinks he can maintain control using hands, feet and legs like any other dive, and has no intention of utilizing a drogue chute to maintain control. We'll see.
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Old 02-07-12, 10:26 AM   #5
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He'll actually slow down as he descends into the thicker atmosphere.
Doesn't terminal velocity mainly revolve around the principle of a lack of further acceleration?

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By the time his chute deploys, he'll be going no faster than if he'd jumped from an airplane.
What if he sticks his arm out or doesn't? either from a plane at 20,000 or from a balloon at 120,000? what if he sticks both arms out in an las vegas elvis suit?
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Old 02-07-12, 10:41 AM   #6
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Originally Posted by Tribesman View Post
I wonder with the higher start and the lower deployment, how severe is that impact coing to be?
Exactly what I was thinking.

Also, does the person feel any shock from the opening of a shute at such a velocity? And how does that feel/how does one deal with that?
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Old 02-07-12, 10:48 AM   #7
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Also, does the person feel any shock from the opening of a shute at such a velocity?
Yes but the chute harness distributes the shock over the body to lessen it's impact.

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And how does that feel/how does one deal with that?
One tries not to get ones testicles trapped between the leg strap and thigh.
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Old 02-07-12, 10:52 AM   #8
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Can we move on from skydiving - I've done it (slightly lower than 23 miles), I can't afford to do it now but still want, want, want!
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Old 02-07-12, 11:52 AM   #9
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Originally Posted by August View Post
Yes but the chute harness distributes the shock over the body to lessen it's impact.

One tries not to get ones testicles trapped between the leg strap and thigh.
Ouch!!
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Old 02-07-12, 12:10 PM   #10
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Doesn't terminal velocity mainly revolve around the principle of a lack of further acceleration?
As the air gets thicker drag increases, and the object slows down. He may be close to mach 1 at 100,000 feet, but at 5000 feet he'll be down to about 120 mph, or 200 kph.

Quote:
What if he sticks his arm out or doesn't? either from a plane at 20,000 or from a balloon at 120,000? what if he sticks both arms out in an las vegas elvis suit?
With the arms out the drag is increased. If the diver keeps his arms tucked at his sides he'll fall a little faster.

From the article I linked

Quote:
A person has a terminal velocity of about 200 mph when balled up and about 125 mph with arms and feet fully extended to catch the wind.
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Old 02-07-12, 03:36 PM   #11
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Quote:
Originally Posted by Tribesman View Post
Doesn't terminal velocity mainly revolve around the principle of a lack of further acceleration?

What if he sticks his arm out or doesn't? either from a plane at 20,000 or from a balloon at 120,000? what if he sticks both arms out in an las vegas elvis suit?
Many things determine "terminal" velocity, I'll not go into all of them here. Even wikipedia has a decent entry.

Air density has a huge effect on the speed at which an object falls.

In a vacuum, a bowling ball and a feather would drop at the same speed, not so in the atmosphere.

Now, assuming the object is not falling in a vacuum, then cross sectional area of the falling object exposed to the passing atmosphere has an effect on velocity.

A jumper diving head down with arms and legs straight will fall quite a bit faster than the same jumper spread eagle.

What is a parachute other than an object which increases your cross-sectional area against the atmosphere?
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Old 02-08-12, 03:10 AM   #12
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As the air gets thicker drag increases, and the object slows down
Quote:
Many things determine "terminal" velocity,
Yes, and I was wondering what the rate of decelaration due to thicker air would be and how rapidly his high velocity would be reduced, plus how far would he travel before that effect is finished and he would again be at a "terminal velocity".
@Steve, I was just pointing out that it wasn't a constant.
@Osmium, you understand why this is actually a variable...he'll be going no faster than if he'd jumped from an airplane.
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Old 02-08-12, 08:27 AM   #13
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Yes, and I was wondering what the rate of decelaration due to thicker air would be and how rapidly his high velocity would be reduced,
Ah, Ok. That's too many maths , and dependent upon a whole set of variables including his own movements/actions a the time.

Even air density at a given altitude is variable based on a number of factors. Too many variables to give a solid answer, and since he will be falling, the value would be ever changing.

Let me see if I can find a chart somewhere that shows a baseline human freefall velocity at various altitudes. Should be something on the intarwebs somewhere.

Edit: Check this out. Skydiving Fall Rate

Hope that gives you the info you seek.
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Old 02-07-12, 12:04 PM   #14
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Originally Posted by Sailor Steve View Post
No worse than any other. It will be no difference than if he jumped at 6000 feet and pulled the cord at 5000. The drag is all the same.
Iirc you are still accelerating after 1000', but not for much.
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