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sorc

terminal speed impact ??

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Late comer here, but I just saw this thread.

I've seen and heard a few 'bounces'. It's strange because it really depends on the situation. One went in with a pilot chute in tow. He was not in too bad of shape (relatively speaking). Face smashed in but he just looked like he was laying there. Another went in as a no-pull. And contrary to what's been said in this thread...he pretty much exploded. Both the main and reserve were deployed on impact and organs were measured to be in excess of 20 feet from the point of impact.
The difference between them was the PC in tow impacted a plowed field in the middle of summer. The other impacted cold hard ground in the late fall. I can't imagine their impact speed was too different from one another.
Sorry if this is a bit graphic. But it's what happens. I find that being 'sugar-coated' does nothing in this sport. It's better that people know what they're getting into.
"Any language where the unassuming word fly signifies an annoying insect, a means of travel, and a critical part of a gentleman's apparel is clearly asking to be mangled."

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What are the G forces on such deceleration?


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Doesn't matter...they're negative G's, they don't effect ya as much as positive ones.




This is actually un-true, neagtive G's effect the body a lot more. Your average fighter pilot can stay consioud through 5 G's. But 2 -G's would render them unconsious.

Either way it would be the impact that kills you, the G force does not matter. The body is more or less contained as the grass or filed acts as a bit of a sponge. hitting on pavement has more direct impact as there is no re-direction of energy.

Hope this help, but do yourself a favour and Buy an AAD.
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What are the G forces on such deceleration?


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Doesn't matter...they're negative G's, they don't effect ya as much as positive ones.




This is actually untrue, negative G's effect the body a lot more. Your average fighter pilot can stay conscious through 5 G's. But 2 -G's would render them unconscious.

Either way it would be the impact that kills you, the G force does not matter. The body is more or less contained as the grass or filed acts as a bit of a sponge. hitting on pavement has more direct impact as there is no re-direction of energy.

Hope this help, but do yourself a favour and Buy an AAD.



Ummm, so it's the IMPACT that kills ya?...I know, I was being facetious. :$


And I have an AAD...my left hand.

Besides, I got this whole gravity and impact thing figured out...didn't you see my initial post?

When ya hit...HANG ON! :ph34r:


Oh...and you 'G' guesses are a bit off.

"The human threshold is around +7.5 G's, for a trained pilot in a 'G suit.'"

http://hypertextbook.com/facts/1998/PhillipAndriyevsky.shtml


And aerobatic pilots routinely pull more than -2, I know because we had a G force meter in our aerobatic airplane. ;)










~ If you choke a Smurf, what color does it turn? ~

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Oh...and you 'G' guesses are a bit off.

"The human threshold is around +7.5 G's, for a trained pilot in a 'G suit.'"

Actually a pilot without a G suit can hold 9 G's with no problem for at least 15 seconds and longer with a G suit. I believe 12 or 13 was hit in the centrifuge in a G suit when I was conducting High G counter measure studies a few years ago but I could be off by one G there and seat config. has some to do with it as well.

Hell, my resting is 5.5 with no AGSM and 7 is no problem at all with a little strain and no suit.

All that being said, in freefall...G's arent an issue. Under canopy...thats where the fun begins.
SONIC WOODY #146

There is a fine line between cockiness and confidence -- which side of the line are you on?

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I believe Viper pilot's have to maintain concsiousness at 9 G's for at least 30 seconds in the centrifuge.

'Positive' G's and applied when an aircraft is in a regular turn and the pilot is pushed down into the seat. Hence, blood pressure to the brain is lost.

'Negative' G's are applied when the aircraft is making a 'downward' motion and the pilot is pulled out of their seat. Aerobatic pilots routinely reach 5 or so negative G's during their displays. Hence, the blood-shot eyes.

The terms 'positive' and 'negative' don't apply in what we're talking about here. I guess if a jumpers were sit-flying all the way to impact, it could be called 'positive'. But it really doesn't matter. They're dead anyway.
"Any language where the unassuming word fly signifies an annoying insect, a means of travel, and a critical part of a gentleman's apparel is clearly asking to be mangled."

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I'm not making this up - I just calculated that the amount of energy generated by a terminal impact (120mph) of a 200lbs jumper is enough to lift a 6-pack of beer to 13,500ft.

A ridiculous fact of elementary physics, but fact nevertheless. What a coincidence! ;)


P.S. Here's the calculation. The kinetic energy of a 200lbs (90.8kg) bogy moving at 120mph (53.6m/s) is KE = (1/2)MV^2 = 130600 Joules. A 6-pack of 12oz cans weighs about 5-6lbs (say, 2.5kg), to lift it to 13500ft (4120m) requires PE = mgh = 101000 Joules.

By the way, that terminal impact energy is equivalent to 31 grams of TNT.

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I'm not making this up - I just calculated that the amount of energy generated by a terminal impact (120mph) of a 200lbs jumper is enough to lift a 6-pack of beer to 13,500ft.

A ridiculous fact of elementary physics, but fact nevertheless. What a coincidence!



This really can't be coincidence. This fits somewhere in the synchronicity model perfectly.

Edit to add a :D , B| and ;)
Owned by Remi #?

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I'm not making this up - I just calculated that the amount of energy generated by a terminal impact (120mph) of a 200lbs jumper is enough to lift a 6-pack of beer to 13,500ft.

A ridiculous fact of elementary physics, but fact nevertheless. What a coincidence! ;)




I am instantly picturing the giant teeter-totter needed to make this happen.:P

Thanks for the visual.:D
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The terms 'positive' and 'negative' don't apply in what we're talking about here. I guess if a jumpers were sit-flying all the way to impact, it could be called 'positive'. But it really doesn't matter. They're dead anyway.




If the jumper was going in head down they would pull positive G's, head up (sit/stand) would pull negative. A better way to see this is force pulling from the head down is positive/pulling from feet up is negative. God I hate negative G's. Anything over two tickles my tummy.
SONIC WOODY #146

There is a fine line between cockiness and confidence -- which side of the line are you on?

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If the jumper was going in head down they would pull positive G's, head up (sit/stand) would pull negative. A better way to see this is force pulling from the head down is positive/pulling from feet up is negative. God I hate negative G's. Anything over two tickles my tummy.



Still doesn't really apply. The jumper isn't 'pulling' anything. Also, what about face to earth impacts? What's that?

You've got pretty good tolerance if the only issue you have at -2G's is a tickle in your tummy!
"Any language where the unassuming word fly signifies an annoying insect, a means of travel, and a critical part of a gentleman's apparel is clearly asking to be mangled."

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Been pulling lots of G's with no G suit for awhile. Built up finally (not that its any fun :P )

True, G's arent a factor when one smacks the ground at any speed since the impact is what kills, not the G's sustained. I was just clearing the air on G Force...at any rate, the jumper would be dead.

SONIC WOODY #146

There is a fine line between cockiness and confidence -- which side of the line are you on?

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