surviving free fall into the water from high altitude

[Comandante]

Say a man was to fall out of an airplane from high alt (say 7km) (assuming no parachute!), what shape should he mold himself into to maximize his chances of survival on impact and how should he attempt to adjust his position once entered into the water.

 

From what I read around in bits and pieces I got an understanding that once you reach the maximum velocity of free fall hitting the water would be similar to hitting the concrete due to its incompressibility, thus fatal in most instances.

 

My question is, if you can adjust your shape/position so that you pierce the surface of the water on impact and survive it, what position would this be? Legs down first or?

 

Also, would he black out due to rapid deceleration? And, should he survive the impact and not black out, how deep would he sink and would it be possible for him to hold enough air without that air being expelled out during the impact.

 

Since coming up with numbers is probably a lot of work, qualitative opinions will help too.

 

Overall, if everything humanly possible is done to improve chances of survival, what would those chances be, in qualitative terms?

 

I understand that this is a bit of a physiology question too, admin may move the thread wherever is appropriate I dont mind.

[J.C.MacSwell]

Say a man was to fall out of an airplane from high alt (say 7km) (assuming no parachute!), what shape should he mold himself into to maximize his chances of survival on impact and how should he attempt to adjust his position once entered into the water.

 

From what I read around in bits and pieces I got an understanding that once you reach the maximum velocity of free fall hitting the water would be similar to hitting the concrete due to its incompressibility, thus fatal in most instances.

 

My question is, if you can adjust your shape/position so that you pierce the surface of the water on impact and survive it, what position would this be? Legs down first or?

 

Also, would he black out due to rapid deceleration? And, should he survive the impact and not black out, how deep would he sink and would it be possible for him to hold enough air without that air being expelled out during the impact.

 

Since coming up with numbers is probably a lot of work, qualitative opinions will help too.

 

Overall, if everything humanly possible is done to improve chances of survival, what would those chances be, in qualitative terms?

 

I understand that this is a bit of a physiology question too, admin may move the thread wherever is appropriate I dont mind.

 

1. Minimize your terminal velocity by spreading your wings so to speak, arms and legs spread out on a plane parallel to the ground. Some clothing may help but will take some skill to maintain position.

 

2. Curl into a cannonball position at the last moment. Enter feet first.

 

3. Pray that the water is really rough, the bigger waves the better, and time it so that you hit the highest, foamiest part of the largest wave on the right angle. (This may require a little skill as well )

 

Do everything right and you may live long enough to drown.

[insane_alien]

2. Curl into a cannonball position at the last moment. Enter feet first.

 

oh god no. you want to present as little cross section to the water as possible. your body should be straight and feet first, even bend your feet so they're pointing down. of course you want to adopt this position as late as possible so you're just hitting the water as you get into that position.

 

the g-forces will still be high enough to break something, but you might live if you get ot a hospital quickly.

[Newbies_Kid]

wow.. 7km is quite high. Although the person could land in perfect position, still the surviving chance is nearly zero. I imagine that the person will just spear down the water more than 50m depth and has his lung crushed and no longer buoyant. When the brain don't get enough oxygen, the heart beat become slow and the person may suffer nitrogen narcosis and forget to breath.. the end.

[J.C.MacSwell]

oh god no. you want to present as little cross section to the water as possible. your body should be straight and feet first, even bend your feet so they're pointing down. of course you want to adopt this position as late as possible so you're just hitting the water as you get into that position.

 

the g-forces will still be high enough to break something, but you might live if you get ot a hospital quickly.

 

I understand what you are saying, but my plan (hope) is not to hit the water square.

 

In spite of my last line about drowning, I think you could possibly survive intact if you hit a large wave just right. If you are tucked you are less likely to be injured as you are already "folded up".

 

I'm also hoping for foam/rough seas. Water is extremely hard without some air in it, and although you will be at maximum speed as you hit the surface, that surface, given the right conditions, maybe the softest portion of what you'll hit, whereas if it is flat calm it will certainly be the hardest.

[Moontanman]

I'd honestly say the odds of surviving a fall from 7 kilometers would be 0 Hitting water at 210 KPH would force your legs up through your body and kill you on impact (if you hit feet first) the impact would shatter not only bones but cause massive internal bleeding, i doubt you be alive to drown.

[PaulS1950]

Even assuming a minimum terminal velocity of 60 mph, and being able to change to a vertical position with your legs crossed and entering the water feet first (reducing the impact decelleration) your death will result from the massive trauma to legs, spine, neck and internal dislocations. If you were (un) lucky enough to survive you would need critical care immediately to live more than a few minutes. Concussion, spinal compression fractures, torn internal tissues and numerous broken bones would be the minimum damage from such a fall.

[Mr Skeptic]

When falling you want to present the greatest cross-section possible to increase drag and minimize terminal velocity. When hitting the water you want to minimize the cross section to minimize deceleration injuries (they say it's not the fall that kills you, it's the sudden stop at the end).

 

Normally, I'd dive head first with my hands in front, but at that speed I'd be afraid I might break my neck. So instead, I'd go feet first, with the feet in tip-toe position, and the legs crossed and tense to minimize the chance of my feet separating (doing the splits at terminal velocity would not be fun).

 

I wonder how deep in the water you'd go? I've heard of one way of getting rid of people that some governments have done, is dump them from an airplane into a swamp. No funeral necessary.

[Moontanman]

Does anyone really think it really matters what position you are in when you hit? However, in WW2 a bomber crew man jumped out of his bomber and fell from about 18,000 feet, he lived but he fell through a pine forest and very deep snow and slide down a hill, what are the odds of that happening again!

 

http://www.greenharbor.com/fffolder/carkeet.html

 

Think of Nick Alkemade, an RAF tailgunner who jumped from his flaming turret without a parachute and fell 18,000 feet. When he came to and saw stars overhead, he lit a cigarette. He would later describe the fall as "a pleasant experience." Nick's trick: fir trees, underbrush, and snow.

[forufes]

Fall flat like a pancake, that way you'll die quick.

 

but if you insist on atleast attempting survival, the points mentioned above are right, you abo also like to try to spin over yourself like a drill, that way you'll distribute the reaction forces of the lake into your joints more evenly(not all will be linear, as there will be torque)...you may also try to decelerate as soon as you start absorbing the impact, maybe something like spreading your legs might pull your gravitational center back to reduce you velocity as you penetrate the surface.

You may also want to spread out after penetration so to slow your speed and hence your depth which you'll have to swim up from.

But this is seriously highly hypothetical and mostly inapplicable by even the best divers. You may just wanna do some stunts in the air, enjoy the scenery, and aim at land if possible :-D

[michel123456]

World Record Highest Dive

 

He enters the water as described by Mr skeptic.

 

I am not a fan of RB but they have a wonderful picture (from another contest):

 

Edited June 7, 2010 by michel123456
Consecutive posts merged.

[John Cuthber]

Nice pic.

 

I think the best shape might be a cross; a star of David; or some such symbol (depending on your personal beliefs).

Nothing else is going to save you.

Incidentally, does anyone have any strong evidence about how soon you would die for a head first dive or a belly flop?

I think it would be slightly quicker head first, because you would hit the water faster and crush your skull to mush over a shorter interval. On the other hand I can see that the massive organ damage caused by landing flat would see you out of this world and into the Darwin awards pretty quickly too.

[Mr Skeptic]

I think the belly flopper is going to kill you quicker. You get to crush your head (if it crushes at that speed), but if not, I expect the temporarily increased blood pressure will burst all your arteries. In any case, a belly flopper hurts even at swimming pool distance falls.

[PaulS1950]

A "belly flop" at 60 mph is likely to split the skin open and leave you a mass of jelly with some manner of attachment to the bones (maybe).

[Double K]

I think most parachute enthusiasts would agree they would rather hit earth or trees than water.

 

Water is very unforgiving, if hit at velocity it's worse than hitting concrete.

Also there are several military techniques that apply this, take a look at

HALO (not the game) and also SAS.

 

HALO perform high altitude drops but deploy chutes at around 4000feet.

SAS will disengage from their chute while still in the air and freefall into the water

This episode shows his technique unfortunately it cuts off just before he detaches...you should be able to find it with a little searching.

[Comandante]

World Record Highest Dive

 

The guy in the video hurt his hands a bit I think, didn't seem like he had time to properly position them before impact. Nonetheless, nice jump. I wouldn't do it

 

I've jumped from decent heights of about 10m or so some time ago, and I also noticed that once going down legs first I was also able to bend them outwards and so make a partial loop in the water whereby at the end of the dive my legs would be pointing upwards towards the surface and head would be pointing down, this way I prevented myself from going any deeper than I should be (had I maintained straight position) and I'm wondering if the same trick would work for high-alt jumps

 

@forufes; I don't know about spinning yourself, maybe it helps for impact protection but how would you manage to swim out disoriented..

[forufes]

World Record Highest Dive

that is NOT what i had in mind.

 

what's up with all the flips? is he mad?

 

AND he actually pulled it off, all the acrobatics then a perfect hit, you can't do that without serious calculations and immense training and.... i just can't in hell see how he did it!!

[John Cuthber]

At about 3:50 in that video you can see that one of the judges has only given him 7.5 out of 10.

If I had just done that jump and got 75% from some ****** I'd have taken him up and thrown him off to see how well he could do it.

[Phi for All]

When there are 5 judges, the highest and lowest scores are thrown out, so he ended up with those three 9s and that second judge didn't affect his score. But you can see the middle judge looking back at the second judge's score like, "WTF?! Dude...."

[John Cuthber]

All I'm saying is that if I had done that and got that score it wouldn't just have been the score that got thrown.

[Phi for All]

Yeah, there's something going on there. Everybody there knew that was an awesome dive except that second judge. I don't know what he thinks he saw but there is no way that dive deserved a 7.5.

 

Before you take the judge up that ladder, let me turn the platform around to face the other side.

[Severian]

what's up with all the flips? is he mad?

 

If you listen to the commentary, he was actually doing this in a competition, so presumably he is trying to get more points.

 

As to the original question, probably the best thing you can do is to be limp and relaxed. The worst thing is to take all the impact on one go, which is what you do if you are rigid. It is is the impulse which kills you, so you want to reduce that as much as possible.

[Mr Skeptic]

As to the original question, probably the best thing you can do is to be limp and relaxed. The worst thing is to take all the impact on one go, which is what you do if you are rigid. It is is the impulse which kills you, so you want to reduce that as much as possible.

 

Limp and relaxed sounds like a terrible idea. You minimize the impact by minimizing the area of impact/drag, and being limp means you can't do that and the forces could pull your limbs in different directions increasing the drag on them yet more.

[mathias]

You don't need that high altitude. A jump from a tall building or bridge would most likely kill you. Chances of living when falling form a plane would be good only if you were Arnold Schwarzenegger, otherwise you would be scrambled behind any chance of recognition. DNA would have to be used to verify your identity.

[losfomot]

Just a comment...

 

The diver jumped from 172 feet (or 52 meters). If you work it out, he should be going about 115km/hr by the time he hits the water. Wikipedia gives the Terminal Velocity of a skydiver belly down as 195km/hr. So, our world record diver was going almost 60% of terminal velocity when he hit.