Could a human survive a fall into water with exoskeleton armor?

Question

When a character jumps into water from a great height, they would normally be severely injured, as displacing the water to decelerate is harder than displacing the impacting body. If the body is soft, it will easily deform. That's why, in my story, I want someone to jump into water wearing armor. It covers every inch of their body, and the extremities are all locked into place. (future setting, powered exoskeleton) For all intents and purposes, the armor acts like a solid figure. Now, would the character be able to survive a fall? I'm curious about both the impact as well as the deceleration, assuming they travel at terminal velocity.

Answer 1

It's not about how hard it is, it's about how breakable and springy it is.

Pure steel armor would be bad. It would be like you hitting a steel floor, and would crush you.

But, a futuristic exoskeleton could have a fancy composition. You want it to crumple, like crumple zones in cars. This means the person inside is slowed down over a longer time period, and will take less damage. You can survive slowing down from a huge speed if you slow down over a long enough period.

You also want it to be springy. Rather than be hard and inflexible, it should compress when you hit it. This will extend the time you slow down, making you hit the water less hard.

Ideally, you also want it to move to lessen the speed. You should be flat, to maximize your surface area to the air to slow you down till just before the impact, which should be legs first so that your surface area to the water is minimized and you can flow through the water rather than being quickly stopped.

Answer 2

You will not survive

Movies like Iron man suggest that a suit of armour is all you need to survive big impacts. However, physics works differently. A quick look at cars shows us why.

Cars used to be build as strong as possible. The stronger the car, the better! Unfortunately this is not the case. With big crashes the car had little damage. However, the person inside the car was dead. This is because of inertia. The body of the person inside the car continues to travel, while the car goes to a standstill. The body hits the car and deforms anyway, while the car stays rigid. It is like hitting a concrete wall, but in this case it's the car!

Having an armour will just shift the "concrete wall" to be right against your skin as you hit the water. Especially as hitting water at high speeds can be harder than hitting concrete, as water deforms slower at high impacts than concrete.

What you want is a more gradual slowing down as you hit something. That is why current cars deform by impact so easily. The deformation slows the vehicle and the person down at a more acceptable pace in a short time. It still is a big ordeal, looking at anyone who has been in a big car crash. But at least it's survivable. You still have some strength here and there, so the car doesn't deform into the person.

So you want an armour to be able to slow down the impact. If it is a "fixed" armour in strength, you want it to be big (unsuitably big for any normal armour purposes) and able to deform upon hitting to slow down the person as equally as possible in the short time of the impact.

Answer 3

If you need a real-world example of this not working, the Space Shuttle Challenger exploded 73 seconds into flight. What is less commonly known is that the cabin survived intact

The explosive force sheared metal assemblies, but was almost precisely the force needed to separate the still-intact crew compartment from the expanding cloud of flaming debris and smoke. What the best data tell the experts is that the Challenger broke up 48,000 feet above the Atlantic. The undamaged crew compartment, impelled by the speed already achieved, soared to a peak altitude of 65,000 feet before beginning its curve earthward.

It was an unsurvivable scenario with this terrible note at the end

The evidence led experts to conclude the seven astronauts lived. They worked frantically to save themselves through the plummeting arc that would take them 2 minutes and 45 seconds to smash into the ocean.

This article notes

The cabin would have hit the water at about 207 mph, creating a force equal to about 200 times that of gravity, he said.

The force of the crew compartment hitting the ocean, which was ″far in excess of the structural limits of the crew compartment or crew survivability levels,″ caused such destruction that the experts were unable to determine the precise cause of death, Kerwin said.

If you want to make your armor increase survival, it needs to emit some energy to slow the wearer's fall to the point where the armor can absorb the rest without injury to the wearer.

Answer 4

Can you use Alexandre Despatie as an exoskeleton?

This should be effective for diving as well as dating.

Needlepoint

Your boring exoskeleton fashions itself into a large space with a very sharp angle that penetrates the water. Moving so much water takes a lot of energy, but you have a lot of energy. The angle at the tip can be arbitrarily narrow, so the rate of deceleration can be arbitrarily small - if we suppose near-magic strength in the refashioned structure.

Active measures

The exoskeleton contains miniature nano pumps that suck up water even faster than you are travelling, and push it all through small very high pressure channels to the other side to release it. All of this is done with advanced knowledge of turbulence to maintain near-perfect laminar flow, dissipating and consuming almost no energy in the process. You simply pass into the water and keep going. What happens when you reach the bottom of the ocean will be left for another question.

Answer 5

Depends on a lot of factors, including the weight of the armor. Ironically, heavier armor makes you a lot safer. If the armor has a lot of mass compared to the water it needs to displace, the total deceleration will be slower and the shock of impacting the inside of the armor will be lower. This will also cause you to go deeper, but that's something armor will be good at protecting you from. And you'll have no chance of swimming by muscle alone, but it's power armor.

Answer 6

Armor works by displacing an impact over a large area: instead of the pokey things making holes, the impact gets spread out over a larger area of the body. This is why pushing one side of a thumbtack is really painful and the other is not. This is also what water does, so armor clearly won't help by itself.

Skydivers falling in "spread eagle" position reach about $53 \text{m/s}$ or $120 \text{mph}$. Of course, landing "spread eagle" increases mortality. Supposing it takes a literal second for a suit to a) orient the body feet first and b) bring feet and hands together into some sort of ideal landing position ("pencil" position), the velocity at impact is $63 \text{m/s}$.

For a feet-first landing, a human can safely accelerate at as much as $98 \text{m/s}^2$ for 3 seconds (which it wouldn't need - at $10g_0$, the user comes to rest under a second with a maximum depth of about $20\text{m}$). Let's say that the suit can alter its friction with the water to control the deceleration. At $5g_0$, it takes $1.3\text{s}$ to reach a final depth of almost $41\text{m}$ which is pretty deep. If the suit doesn't control the user's face and ear environment, eardrums might pop hazardously upon arriving at the depths.

The human body actually performs better accelerating in the face-ward direction, so a cleverly designed suit would adapt a curved pencil position so the human starts facing forward and finishes facing up so that their water trajectory starts vertical and finishes horizontal.

There are tons of variables here. A clever suit would aim to impact the roughest water surface, and it might shoot things at the water to make it rougher (which would insignificantly slow the user). A heavy suit has a higher terminal velocity, but it could also have membranes that add to the cross-sectional area during free-fall. If it did have membranes, a skipping-stone type trajectory would be really advantageous.

The exoskeleton suit conceit is a pretty big one, but if you grant that, surviving a long fall into a deep ocean should be fine.

Answer 7

If the armor is light enough it's survivable with injuries.

An unprotected human being can survive a water landing if everything goes perfectly. The entry angle needs to be just right and you need to stay conscious and get back to the surface before you drown. Unlikely, but it has happened and there are also some who died from drowning, not from the impact.

The armor can ensure the perfect entry and it can provide air to breathe even if you are knocked unconscious. Thus it becomes a high risk scenario, not a basically certain death scenario. Something users would never train for but would know about.

Answer 8

The suit can be create a superhydrophobic surface.

By creating a bubble of air around the suit, you can reduce drag in the water. You need a lot more depth to decelerate (so no shallow landings)

This is the remarkable result from a series of experiments that have for the first time shown objects sinking in water with close to zero drag, finally proving an 18th century theory in physics.

...The experiment looks simple. Drop a 2-centimetre-wide metal ball into a deep pool. The ball forms a large gas bubble in the shape of an elongated teardrop around itself and then the ball-plus-bubble sink together. Do the maths and it turns out that this ball experiences ten times less drag than a solid object with the same shape.

https://cosmosmagazine.com/physics/a-ball-in-an-air-bubble-can-slip-through-water-with-almost-no-drag/

Answer 9

The armor may be a "solid figure" and can survive the fall undamaged, but the squishy internal human will still suffer from terminal deceleration without some sort of magi-tech inertial compensators or something similar.

One potential solution would be some sort of jet system in place to reduce falling speed down to a survivable value. Whether such a system would be a part of the suit, or a detachable "jetpack", or even a drone, would be an exercise for the writer.

Such a jet system would allow the suit to drop at terminal velocity until much closer to the ground than a more passive system (like a parachute), but will still require some distance to stretch the deceleration down to human tolerable levels.

Answer 10

From a physics point of view, Newton's second law states $F = m a$. In other words, the amount of force ($F$) you experience is proportional to how quickly you're accelerating ($a$).

Water doesn't really compress so you'll hit the water at free-fall speeds and decelerate to zero velocity within a fraction of a second. That means $a$ is very large, as will be the forces you experience. Having a layer of armor won't really help, your deceleration is the same so the overall force imparted on your body is the same.

There are two ways to reduce the force of such an impact: shed mass, or decelerate more slowly. The former isn't practical for a free-falling human. The latter is used frequently in the real world. An acrobat falling off a tightrope could be killed by the sudden deceleration of an impact with the ground. A safety net solves this problem by slowing them down over a period of time. If a sudden impact would decelerate you in 0.1 seconds and a net would decelerate you over 5 seconds, then your body will only be subject to 2% of the force of an impact. That's why tripping and falling on concrete hurts, on carpets hurts less, and on a mattress doesn't hurt at all. As an extreme example, this is also how you can jump off the top of the Stratosphere hotel, fall at speeds over 40 miles per hour, and still land safely at the bottom.

Answer 11

The problem that needs to be solved is basically the high acceleration that the person in the suit will experience. I see different approaches to reduce the acceleration.

The force the person is being accelerated with (water drag resistance) depends on the drag area and speed (Drag Area).

I guess you try to avoid reducing the impact speed, that factor is considered constant. Instead, you could for example reduce the drag area by using streamlined shapes for the armor. The lowest drag coefficients are eg. found in planes and are about 2-3 magnitudes lower than the human body. Depending on the impact velocity that might already suffice.

Another idea is to consider the force as constant and just a full body armor. Since the acceleration is proportional to the mass, you could simply make the suit very, very(, very) heavy. The impact on the falling velocity would be considerably low, but the braking distance would be increased. Of cause the stress on the suit would be higher as well, so the mass increase should be at the lowest point possible.

A combination of the two solutions will of cause also work.

EDIT: This will only work for sufficiently deep water!

Answer 12

Use a wingsuit

All previous answers assume an uncontrolled "splashdown". But with exoskeleton armour, there's no reason why it couldn't feature deployable flying surfaces. Unlike a parachute which is a "one-and-done" situation (as mentioned on a deleted answer), these flying surfaces could easily be stowed after landing. The design could use rigid surfaces, or could be flexible (maybe Kevlar). They would deploy from canisters mounted on the back of the armour down each side, and could be stowed back the same way.

Landing a wingsuit is not just a hypothetical situation. Gary Connery has actually landed a wingsuit on a runway, using cardboard boxes to slow his speed. He landed with 50mph forward speed and 15mph vertical speed. This is well within survivable limits for a water landing as-is. When you consider that a well-executed flare could allow you to scrub off your forwards speed by planing over the water, it looks even more achievable.

If we consider that the exoskeleton could also present a reasonable level of impact cushioning, to mitigate the effects of impacts (bulletproof vests still injure you, they just don't kill you) or explosions, then this could even be a survivable option on land. It's definitely going to hurt, and your suit is probably not going to survive, but you've got reasonable odds of making it. A soft LZ (trees, snow, sloping terrain which scrubs off speed more gradually, etc.) will definitely push things in your favour.

It's also worth mentioning that current wingsuits are inherently limited by the dimensions of the human body and the forces that arms and legs can sustain. Powered armour does not have these limitations. Telescoping struts could extend out from arms and legs to provide a greater wing area. It's not going to turn this into a full-on hang-glider, but it could give enough control to take you down safely with a non-terminal terminal velocity.

Answer 13

The Armor Doesn't Matter Much Unless It Has Wings

For a given shape, terminal velocity is proportional to the square root of weight.

For a given shape, drag force in water is proportional to the square of velocity.

Deceleration in water is proportional to force/weight.

So for thinish armor, if the armor, say, quadruples the wearer's weight, then it doubles his terminal velocity. That quadruples the drag force in water, but deceleration is the same. The portion of the deceleration force that the wearer bears is the same. If it doesn't change his shape, then the armor makes no difference to survivability.

If, as @LorenPechtel says, it's barely possible for a human to survive a great fall on his own, then it would be similarly barely possible to survive in armor, and you'd suffer a lot less stinging and minor injuries.

The best thing the armor can do for the wearer in this situation, though, is to alter his shape in a beneficial way. You want to increase the cross-sectional area while falling through the air, and then alter shape or orientation to minimize that cross-sectional area just before hitting the water.

It is the ratio between these two cross-sectional areas that determines whether or not the wearer will survive. Any kind of wingsuit-like structures webbing the limbs while falling would make the whole ordeal a lot more pleasant.

Supercavitating structures on the entry surface (head or feet) would help a lot too, but they're funny looking and you don't really need them.

Answer 14

Having read previous answers, it seems to me that, to survive, your futuristic armour would need to manage the deceleration. It can extrude fins and whatnot from its outer layer that allow it to control glide during falling, and at the water surface, become more spear like so as not to smack into it. This armour is very active and it's looking ahead. If the water is too shallow, perhaps it has the foresight to extrude winglets that promote lateral glide as a means of reducing vertical speed.

A technique I've heard about (citation needed; not tested by me; don't try this at home) for entering water from a great height is to put one leg forward and one leg backward, making an upside-down V-shape with them, whilst tightening your rectal sphincter (to keep the high-pressure water out...). I cannot remember if the advice included holding the arms out, but you can imagine an armour suit using the arms as part of the solution. If I read it, I'd believe it.

Answer 15

If we rule out a flying suit of armor like Iron Man I can think of uses for items helpful for more than just surviving a fall from great height, and for landing over land or water. An example of a single function item is a large parachute or parasail. This would be essentially a one-time use thing, as once deployed it would need to be carefully reset. That assumes it was not damaged or had to be discarded. Because it is easily damaged and not easily reset for another use there may be a need for more than one to be useful which adds to the bulk, and again useful for basically one thing.

What of a combination of airfoils, thrusters, and airbags that can deploy and retract quickly?

Airfoils would help in maneuvering while running quickly, keeping feet on the ground, or off the ground by hopping/gliding over obstacles. Also useful for making a quick stop or turn. Thrusters could add to this, in addition to greater acceleration in a run and possible use as a weapon. Some sturdy airfoils can be armor that flips up and down to cover vulnerable points on the armor, or cover an ally. Some not so sturdy airfoils would still work as a kind of ablative armor, as they break up they take some "heat" out of projectiles or punches. Of course in a fall airfoils can help in slowing down and aiming to a safe (or safer) spot for a landing.

Airbags that can quickly pop up, and be deflated back to where they came from, can help in a fall by increasing area to add air resistance and slow down. Maybe useful with airfoils, maybe not. The air in the bags would cushion the landing on air or water. If on water then it provides flotation. Then comes other uses. If the pilot of the powered armor can't jump out of the way of an oncoming train fast enough then airbags could soften that blow. Also useful for landing a soft punch, like boxing gloves, if the goal is deterrence over injury.

There's creative ways airbags can be used for those that are fans of MacGyver. You need to lift a section of wall toppled by an earthquake or storm? And carefully to free some trapped... um... (think something cute, and fuzzy, and endangered)... polar bears? Then crawl under a small gap and inflate the airbags to lift the wall and make a hole big enough for the bears to climb through. Need to anchor yourself to a rock face along the beach so the next wave doesn't wash our hero out to sea? Stick an arm in a crack in the wall and inflate to get wedged in tight. Need to look big and intimidating to scare off some endangered, um... polar bears? Puff up real big and growl over a PA. Add in a blast of air towards the bears with the thrusters to add an effect of breath from a big animal.

Answer 16

Use supercavitation

The other answers are right that ultimately, what matters is the amount of decelaration. However, unlike with cars, the way to limit that is not a crumple zone. You could use a crumple zone, but the size of that can only be so big, and after it's crumpled and you're still going fast that's it then.

Instead, you should capitalise on what high divers are doing already: enter as far as possible into the water. Do not make the armor squishy.

The problem is of course that water does get “hard” if you hit it quickly, sometimes said “harder than concrete”. But this is a simplification. For a flat impact, yes, it would be absolutely deadly, but if you're doing it cleverly then you can actually enter with much less resistance. Some already suggested a long spike. The trick would be to allow the water to get out of the way in a slower horizontal motion, to make place for the much faster vertical movement of the diver. The spike has to be sturdy, and it helps if it's really heavy to pull the vehicle into the water in straight, stable motion and with less deceleration for the same forces.

But there's an even better strategy: supercavitation. It's the principle used by high-speed torpedoes, and that's basically what you need to be, except you don't need to worry about getting to that velocity, just about not losing it too suddenly. I'm not sure how reliable Wikipedia's figure of 400 km/h for such torpedoes is, but it should certainly be enough to make this survivable.

Plus, the supercavitation effect works only in water, i.e. the diver can still have a bad aerodynamic shape and/or lower mass, meaning the terminal velocity will not be increased so much, whereas the water resistance will be much less.

Answer 17

1)What weapons are on the armor and how strong is it? Can he use successively fired concussion grenades ahead in his fall path to slow his descent and later break the surface tension without taking excessive damage?

2)What sort of fauna are on the planet? Could there be a Sea-Forest with above water foliage and small branches to break his fall?

3)Is the character more sturdy or mass dense(from a heavy gravity world)? The planet's gravity would be less effective on his mass and the impact could be partially mitigated.

4)Is the character hollow boned or the like , like a bird(from a light gravity world) such that his fall speed would be reduced due to his lower mass?

5)Does the character have any psionic abilities to airbend or waterbend through telekinesis?

6)Is there someone/thing watching him fall? An ally that could slow his descent with some kind of technology?A jetpack, a force field projector or skynet for catching dropped cargo?

7)A sky creature that tries to snatch this shiny snack from the sky eating him or breaking his fall... OR sea creature that jumps up out of the water to grab and eat the falling morsel or shoot it with slime or water that breaks his fall... OR a sea creature that eats the sky creature that ate the falling character...ala out of the frying pan....

Answer 18

Maybe, if your suit is based on UFO technology.

Recently, the US Government has publicly announced that UFOs (now officially called UAPs, for "Unknown Aerial Phenomena") are real, and that they have a host of exotic properties beyond our current understanding of physics; the former head of the previous UFO investigation group, Luis Elizondo, has labelled several abilities that they consistently possess the "five observables". One of those abilities that they've demonstrated is what the US government calls "Trans-medium capabilities", meaning that they're freely capable of flying between air and water without any damage or loss of maneuverability or speed.

If your hypothetical suit of power armor is based on these technologies, then presumably it would also have trans-medium capabilities that would allow it to freely move through the water as well.

Answer 19

It depends on many factors; how would the person jump in the water, with feet first or maybe with stomach?

A friend of me jumped 35m; as non cliff jumper he only jumped just once from the 10 meter tower.

I survived that stupid experiment ... we spoke with the people who were there too and live there. They told us that 3-4 times a week a helicopter has to come because the most of the injuries are sprained pelvises.