Surviving a terminal velocity fall to earth?

[speedy_thrills]

Ladies and Gentlemen,

As I was watching racing the other day it occured to me that the terminal velocity of a human falling towards earth is only about 200km/h (120mph.) Could this be easily survived with body armour instead of a parachute?

I know there have been cases of people surviving falls from aircraft by landing on soft objects and there is a video online of somebody skydiving onto boxes but I was particularly interested if body armour could perform the same task. I was thinking something like an inflatable body suit or zorb.

It seems to me motorcycle crashes are often survived where the speed of the rider is greater than 120mph at the time they plough into a wall or tyre barrier.

Thank you for your time in considering this question.

[untakenname]

The deceleration will be instant with solid ground so armour won't help, only chance of survival is if the person scrubs of speed through a tree canopy and even then the injuries will be life changing.

Edited by untakenname on Sunday 1st August 01:36

[GliderRider]

untakenname said:

The declaration will be instant with solid ground so amour won't help, only chance is if the person scrubs of speed through a tree canopy and even then the injuries will be life changing.

Nicholas Alkemade, a Lancaster tailgunner, survived with a sprained leg. He fell, without a parachute, from 18000ft, fir trees broke his fall before he landed in a snow drift. At least four other people have also survived terminal velocity falls from aeroplanes.

[dudleybloke]

A few people have survived but with injuries, soft boggy ground helps.

[speedy_thrills]

I can see that the freedive record is about 60m and he would have hit the water at about 30m/s. However it looks like in freefall a person would be doing circa 55m/s so obviously they would likely need additional protection to avoid injury.

Wikipedia has a short list of people who've survived falls from aircraft etc. and how they survived:
https://en.m.wikipedia.org/wiki/Category:Fall_surv...

Edited by speedy_thrills on Sunday 1st August 02:40

[Scottish Wyldcat]

I recall seeing a video somewhere of a skydiver diving into a stack of cardboard boxes without parachute?

[rxe]

It’s all about the deceleration. At about 10G or so, your heart detaches from its plumbing with predictably poor effects. It’s why 70mph crashes tend to be fatal, even if the structure of the car survives. So decelerating from 120 -> 0 in 30 metres of fir tree …. survivable. 120 -> 0 in an Iron Man suit - fatal.

[Nimby]

Mythbusters have investigated this :

Edited by Nimby on Sunday 1st August 14:43

[Maximus_Meridius101]

There have been a few examples over the years. It’s possible, but you have to get very lucky, or be insane enough to do this.

https://m.youtube.com/watch?v=GaANi96Z-Wg

[sociopath]

GliderRider said:

untakenname said:

The declaration will be instant with solid ground so amour won't help, only chance is if the person scrubs of speed through a tree canopy and even then the injuries will be life changing.

Nicholas Alkemade, a Lancaster tailgunner, survived with a sprained leg. He fell, without a parachute, from 18000ft, fir trees broke his fall before he landed in a snow drift. At least four other people have also survived terminal velocity falls from aeroplanes.

I remember reading that story as a 10 year old

[elanfan]

If your heart plumbing detaches at 10G how did Max Verstappen survive 51G?

[eharding]

elanfan said:

If your heart plumbing detaches at 10G how did Max Verstappen survive 51G?

It doesn't, is the simple answer. John Stapp put himself through rocket sled decelerations up to 42g in the 1950s, and as you observe people have survived significantly higher than that.

[frisbee]

elanfan said:

If your heart plumbing detaches at 10G how did Max Verstappen survive 51G?

How do people survive jumping off a wall? That's 10s of Gs, especially if you forget to bend your knees!

[Maximus_Meridius101]

The heart detachment thing, is an impulse issue. It’s the rate at which peak G is achieved that causes the issue. A huge triangular acceleration graph will kill you, if it’s more like a Mexican hat, you stand a better chance of survival.

[rxe]

Maximus_Meridius101 said:

The heart detachment thing, is an impulse issue. It’s the rate at which peak G is achieved that causes the issue. A huge triangular acceleration graph will kill you, if it’s more like a Mexican hat, you stand a better chance of survival.

Indeed. It’s the rate of change of the rate of change of velocity. Smacking into something immovable with an instantaneous spike to 10G will do damage. Gradually ramping your acceleration will not do so much damage. The direction also matters - you’re more likely to rip your aorta when it is accelerating down through your diaphragm.

[GroundZero]

elanfan said:

If your heart plumbing detaches at 10G how did Max Verstappen survive 51G?

If you plot a graph of G vs time then it would look a bit different between hitting a tyre wall and hitting solid ground.

In the case of a tyre wall the build up of G is 'smooth', where as comparatively hitting the ground, the build up of G is 'instant'.
G is acceleration/deceleration, but its about how quickly it takes affect.

There is a typical "crash test" that used to do the rounds that over-stated the effect of a car crash as a public promotion for the advocation of reducing speed limits up and down the country. Whereby a person would sit on a chair that was on a railed incline. The chair would then slide down about only 0.5m whereby it would impact on a solid metal stopper, and thus giving a sudden stop impact. The effect of this massively overplayed the effect of a real crash at that speed whereby the vehicle's crash structure would absorb the energy and provide a very different graph of G over time. In this case it was designed to spike as much as possible in order to create the desired visual effect and also make the person in the chair feel a spiked impact.

[Desiderata]

Years ago I had a relatively small fall from a ladder onto concrete, I landed on my bum in a sitting position and apart from a couple of tenderised cheeks, I had no external injuries. I pissed blood for about a fortnight though and felt winded and nauseous for a few days. The doctor explained that it was similar to dropping a carrier bag of butcher meat onto a pavement, nothing showing on the outside of the bag, but the shopping got a bit of a bashing inside.
I'd image that however tough the bag/ body armour, unless it had a hell of a lot of cushioning, a terminal velocity sudden stop would indeed prove to be terminal.

[RizzoTheRat]

I went to a talk by a guy from Martin Baker (ejection seats) several years ago, he reckoned around 70 G is generally considered the maximum a human body can take.

120mph is 53m/s so in theory 1 meter of deceleration should be survivable, but developing something that gives a linear deceleration would be tricky.

The guy who did the skydive in to a pile of cardboard boxes was in a wing suit so he'd have been doing a lot less than 120mph


As for parachutes, it's impressive how effective they can be even at the last minute...

Edited by RizzoTheRat on Monday 2nd August 10:27

[RizzoTheRat]

GroundZero said:

elanfan said:

If your heart plumbing detaches at 10G how did Max Verstappen survive 51G?

If you plot a graph of G vs time then it would look a bit different between hitting a tyre wall and hitting solid ground.

In the case of a tyre wall the build up of G is 'smooth', where as comparatively hitting the ground, the build up of G is 'instant'.
G is acceleration/deceleration, but its about how quickly it takes affect.

Is it Jerk or Deceleration that causes he damage though? Hitting the tyre wall reduces the peak G as you decelerate over a longer distance

How was Verstappen's 51G measured? If it was an accelerometer on the part of the car then presumably extra give in his restraints reduced it further from what was measured.

[GroundZero]

Good question as to how the G is measured on an F1 car as this will make a big difference to the value.
For example, if its within the harness straps of the driver, or whether it is within part of the body work that makes initial impact with the tyre wall, or whether it is somewhere centrally within the car, the values will measure on the onset of G at various rates.