# The Naked Scientists Forum

### Author Topic: Could we skydive safely without a parachute?  (Read 10499 times)

#### DoctorBeaver

• Naked Science Forum GOD!
• Posts: 12656
• Thanked: 3 times
• A stitch in time would have confused Einstein.
##### Could we skydive safely without a parachute?
« on: 29/06/2008 23:11:59 »
Parachutists are (or, at least, were) taught how to bend their kness and roll on landing to lessen the impact. If I remember rightly, it's all to do with transferring downward motion into roly-poly motion to disperse the excess energy. Of course, it has to be done at the exact moment of impact with the ground to be effective. When landing fast, it would be almost impossible to time it right.

So, would it be possible to build an exoskeletal frame with sensors on the feet attached to servos that could cause the frame to move in such a way that the jumper's body would bend at the knees and roll at exactly the right moment to allow them to jump from any height and land safely?

• Neilep Level Member
• Posts: 1451
##### Could we skydive safely without a parachute?
« Reply #1 on: 30/06/2008 04:47:21 »
I think that might be possible from some heights, but not any height. I think a skydiver reaches a terminal velocity of about 200kmph, and even with the best landing possible you're still going from 200 to 0 in a very short distance. The suit would need gigantic suspension springs on the bottom of it to dissipate the energy over a longer distance.

But that said, there are people who have freakishly survived skydiving with a parachute failure

#### graham.d

• Neilep Level Member
• Posts: 2208
##### Could we skydive safely without a parachute?
« Reply #2 on: 30/06/2008 12:10:50 »
A rough calculation suggests that if you want to limit the maximum deceleration to, say, 10g, then from a terminal velocity of 200kmph you would need to slow down over a distance of 15.4 metres. This distance is inversely proportional to the g-force you would reckon to survive, so if you think you could withstand 100g then this would reduce the size of the spring + damper arrangement to 1.54m. But I don't think people could survive 100g, even for the 56mS needed.

People who have survived have either had part opened chutes, landed through trees and/or into deep snow or landed on snow slopes. At least, I don't think there are any recorded survivors from an unimpeded ground impact.

#### blakestyger

• Guest
##### Could we skydive safely without a parachute?
« Reply #3 on: 30/06/2008 12:39:22 »
I love that term 'terminal velocity' - it's just so relevant to jumpers without 'chutes. Who would want to jump out of a perfectly serviceable aircraft anyway - with or without one?

#### Alan McDougall

• Neilep Level Member
• Posts: 1285
• Thanked: 14 times
##### Could we skydive safely without a parachute?
« Reply #4 on: 01/07/2008 13:16:04 »
I do not believe you can, some guys use a type of superman wing stretch over their arms .They glide quite far by this mode of dangerous travel

#### neilep

• Withdrawnmist
• Naked Science Forum GOD!
• Posts: 20602
• Thanked: 8 times
##### Could we skydive safely without a parachute?
« Reply #5 on: 01/07/2008 13:41:04 »
Skydiving without a parachute is very very very easy !

Landing without one is a little tricky !!

#### graham.d

• Neilep Level Member
• Posts: 2208
##### Could we skydive safely without a parachute?
« Reply #6 on: 01/07/2008 16:55:30 »
It has occurred to me in the past that even with a very small and simple, if strong, wing, it should be possible to convert downward motion into horizontal motion. By getting the timing right it should then be possible to stall at the right time. Admittedly you would still be hitting the ground at some considerable speed but hitting it nearly horizontally is hugely more survivable that hitting it vertically as long as you don't hit a wall. Motorcycle racers do this fairly often and walk away thanks to their leathers. Practicing the maneuver to get it perfected seems risky though!

#### LeeE

• Neilep Level Member
• Posts: 3382
##### Could we skydive safely without a parachute?
« Reply #7 on: 01/07/2008 18:14:10 »
Graham.d - there are a couple of problems with this approach.  The first is that a small wing does not produce much lift, so to get equivilent lift to a larger wing you have to go faster.  The second problem is that as you change direction during the pullout, where you try to convert the downward motion into forward motion, the G-force you experience due to the change of direction effectively increases your weight, and in turn, the effective stall speed of the wing.  In the end, the stall speed, for any wing of practical size for this sort of scenario, is likely to be too high to survive without injury.

#### Bored chemist

• Neilep Level Member
• Posts: 8596
• Thanked: 41 times
##### Could we skydive safely without a parachute?
« Reply #8 on: 01/07/2008 19:10:11 »
I think this is a related question; is there a maximum height to "vertical" water slides?
This sort of thing
(not a brilliant illustration I'm afraid).
The slide is near vertical, but, because it changes gradually to a steeper slopwe the forces involved are not that great and, with all that water, friction and heating aren't a problem.
OK, in theory there's a limit because you would run out of air, gravity etc, but is there any limit that would come in before that?

#### graham.d

• Neilep Level Member
• Posts: 2208
##### Could we skydive safely without a parachute?
« Reply #9 on: 02/07/2008 09:59:41 »
BC, I think the answer is no, there is no limit. The gradual curvature at the bottom of the slide allows a controlled deceleration of your vertical speed component. Once horizontal you will eventually stop due to friction.

Lee, I think the wing may have to be too big too but can't be sure. I agree about the speed having to be high (you probably understand that I don't mean this to be a terribly practical solution) so it would be necessary to adjust the body position to get into a flying position and to have a suitably increased speed. With perfect judgement it may even be possible to get into a climb and to make an approach below the height of a building so as to stall and slow so that you could just drop onto the edge of the building without significant forward momentum.

Kids, don't try this at home :-)

• Neilep Level Member
• Posts: 1451
##### Could we skydive safely without a parachute?
« Reply #10 on: 02/07/2008 10:16:44 »
Or it could have wheels to land on then apply the brakes to get rid of your horizontal motion. Sounding more and more like a hang glider, but I suppose you'd be hard pressed getting a hang glider to 200kmph :P

#### LeeE

• Neilep Level Member
• Posts: 3382
##### Could we skydive safely without a parachute?
« Reply #11 on: 02/07/2008 14:10:07 »
With perfect judgement it may even be possible to get into a climb and to make an approach below the height of a building so as to stall and slow so that you could just drop onto the edge of the building without significant forward momentum.

Kids, don't try this at home :-)

LOL - indeed not

This is theoretically feasible, but you'd need a very high building - several thousand ft high, at a guess.  It'd be a long way to drop if you didn't get it right, which nicely brings us back to the start again

#### Andrew K Fletcher

• Neilep Level Member
• Posts: 2331
• KIS Keep It Simple
##### Could we skydive safely without a parachute?
« Reply #12 on: 02/07/2008 18:17:04 »
Bungee cord might be useful just in case your maths is out a tad

#### RD

• Neilep Level Member
• Posts: 8088
• Thanked: 51 times
##### Could we skydive safely without a parachute?
« Reply #13 on: 03/07/2008 02:14:45 »
nutter Wing-suit-man plans to land without parachute by gliding into a tube ...

(fast-forward this video to 2min 25sec)
http://video.msn.com/dw.aspx?mkt=en-gb&from=truveo&vid=4e926822-9a83-4f61-bbcb-2a6fefaeea34
« Last Edit: 03/07/2008 03:09:48 by RD »

#### DoctorBeaver

• Naked Science Forum GOD!
• Posts: 12656
• Thanked: 3 times
• A stitch in time would have confused Einstein.
##### Could we skydive safely without a parachute?
« Reply #14 on: 03/07/2008 07:49:03 »
I tried to watch that video. What a surprise... "Your browser is not supported". The 3rd most popular browser on PC (2nd most popular among those who realise there are alternatives to IE), Opera, and it's not supported. The version that I've got of the 2nd most popular browser (most popular by choice), Firefox, is not supported (I've got Firefox 3). So much for standards-compliant websites, eh.

Good old MS! They really don't like you using anything that's not theirs, do they.
« Last Edit: 03/07/2008 07:52:03 by DoctorBeaver »

#### RD

• Neilep Level Member
• Posts: 8088
• Thanked: 51 times
##### Could we skydive safely without a parachute?
« Reply #15 on: 03/07/2008 20:08:47 »
Just for you Dr B, a nutter skydiving without a parachute on youtube...

#### DoctorBeaver

• Naked Science Forum GOD!
• Posts: 12656
• Thanked: 3 times
• A stitch in time would have confused Einstein.
##### Could we skydive safely without a parachute?
« Reply #16 on: 03/07/2008 20:17:13 »
****

#### RD

• Neilep Level Member
• Posts: 8088
• Thanked: 51 times
##### Could we skydive safely without a parachute?
« Reply #17 on: 05/10/2009 07:57:33 »
Wing-suit-man goes on a flying visit to Switzerland ...
NR=1  [:0]

« Last Edit: 05/10/2009 17:47:24 by RD »

#### neilep

• Withdrawnmist
• Naked Science Forum GOD!
• Posts: 20602
• Thanked: 8 times
##### Could we skydive safely without a parachute?
« Reply #18 on: 05/10/2009 12:42:59 »
I tried to watch that video. What a surprise... "Your browser is not supported". The 3rd most popular browser on PC (2nd most popular among those who realise there are alternatives to IE), Opera, and it's not supported. The version that I've got of the 2nd most popular browser (most popular by choice), Firefox, is not supported (I've got Firefox 3). So much for standards-compliant websites, eh.

Good old MS! They really don't like you using anything that's not theirs, do they.

Works ok for me Dr beave..on firefox 3

#### DoctorBeaver

• Naked Science Forum GOD!
• Posts: 12656
• Thanked: 3 times
• A stitch in time would have confused Einstein.
##### Could we skydive safely without a parachute?
« Reply #19 on: 06/10/2009 01:09:55 »
Works for me now, too. The guy is mental!

RD - that clip is amazing. What a feeling that must be.

#### The Naked Scientists Forum

##### Could we skydive safely without a parachute?
« Reply #19 on: 06/10/2009 01:09:55 »