Bullet proof water?

[ravens_hawk]

Ok I was watching Mythbusters the other day and they were testing the myth of bullet proof water. You know dive under a few feet of water and no bullets will hit you, standard movie plot devices. At first I was thinking, sure this is true it's what forensics use to fire pistols into to compare bullets. But it surely wouldn't stop high powered rifle rounds. Then they did one test with a 5.56mm and I remebered that whole wounding pattern experiment. Nearly all supersonic rounds break up when hitting flesh, which I'm guessing acts alot like water in this case. So basically unless their firing subsonic (particularly pistol rounds, which probably won't do much damage after say 10 feet) about two feet of water will stop the round.

The real point to this post (wait this is off topic, I don't need a point) is how many game have we seen that bullets fired into or through the water still not only hit but injure their targets after several meters. I know INF is one offender, but I've seen it in almost every game I've played. Not that we could change it in INF (I doubt the engine would allow it, and no one would work on it) but let's go on a realism rant on all the other forums and spread the Holy Ideals of INF.

[geogob]

I *could* implement that quite easily in Real Targets... I could... *sigh*


edit: understand, not en engine limitation. It's 2 lines of code (or so) to add. All mechanisms to slow bullets down in water are there.

[ravens_hawk]

Wait so you can adjust the rate of deceleration in water? Can you change it based on the speed and mass? (Idealy this would be drag = k*m/v.) I thought water was treated just like any other object, it would slow down based on UU thinkness. Why not make impenetrable objects by creating an inch of water in between two layers of wall and set the water to stop the bullet? I'm guessing I'm missing something here.

[geogob]

yes you are :P
I can calculate deceleration for water because it's a zone and I know when the projectile is in this zone.

For materials it's nother story. It depends on the texture and other stuff. Not as easy. Especially since the attach decal function is stupid.

[ravens_hawk]

So why not setup a zone (ie water) within a wall to make it stop bullets? As opposed to making the material thicker...

Ok this is going off topic for off topic ;)

[yurch]

That involves changing the map or otherwise adding info that isn't there for use at the moment.

Nothing other than the texture in UT says that this bit here is wood or metal...

[geogob]

well what would be the point in doing that? and how much water would you need to have the same effect as 2 inch armor plating? Tank with 3 meters water plating o_0

[ravens_hawk]

Well actually to stop high velocity rounds you wouldn't need much water, or water like substance around it, as it's likely the surface tension that shears the copper jacket from the bullet and causes it to fragment.

My point was in creating maps for INF that had thin walls that could stop bullets. IIRC there were errors with using different textures that prevented people from stopping rounds with anything less then a meter or so of material.
Maybe I'm misunderstanding some of the previous mappers remarks...

[BTH]

you must remember that water only stops bullets at certain angles, a perpendicular shot will pierce water, a shot at 45 degrees will slow the bullet down drastically and probably refract its trajectory, and a shot at 20 degrees will make the bullet break into small fragments. I guess with nades a 40mm could even blow up upon hitting the surface of the water at a correct angle, or hit the depth so softly it wouldnt go off

[geogob]

you must remember that water only stops bullets at certain angles

no

water is water. period. It's not some odd material in cristaline form that has different caracteristics depending on the angle. It's a liquid.

[Harrm]

Actually, it would change the trajectory of the bullet (elemtary physics) towards the perpendicular. Not much, but it would. But I highly doubt it would only stop the bullet at certain angles. The total resistance of the water doesn't change, only the total force exerted on the top of the water which doesn't mean crap if the bullet if the resistance of the water is enough to break up the bullet anyways.

--Harrm

[Cap'n Beeb]

Since when do most supersonic rounds break up?

Also:

http://beerbaron.kibblesnbits.net/SA/Misc/mythbusterthing.avi

[BTH]

see the video? that was a 50 cal, the target was only 1 metre under water and not one chunk of the bullet hit it. I believe in a perpendicular shot the bullet wouldnt've blown up, but just get slowed down

[UN17]

Wow, M82 against a swimming pool. Those Mythbusters are crazy! So the next time I'm being chased by crazy terrorists I just have to jump into a local swimming pool. Unless they have grenades. I think that would cause some kind of aquatic overpressure shockwave or something.

[BTH]

probably Frag nades have a reduced effect underwater, but High Explosive have an increased effect, just check dinamite fishing

[ravens_hawk]

Ok as I understand with the way most copper jackets are composed, when they impact with a liquid or water like substance (flesh acts similarly) at high velocity, (usually above 1500ft/s) the shear force of impact breaks up the copper jacket. It's likely due to the way water behaves at high velocity, high surface tension and all. I don't think it has anything to do with the angle.

[Clutch]

i disagree.. i think angle WOULD have an effect.. if you shot straight down into the water, the bullet would just glide through because of the shape.. the bullet hit the water at an angle so more of the bullet hit at the same time, kind of like diving compared to a belly flop. if you jump from high enough and belly flop, say goodbye, but if you dive, you go straight down with little resistance. it all has to do with aerodynamics and angle. your arms break the water just like the tip of a bullet would.

making this effect in a game would be a bit too complex, the most i could see being done is making the bullet slow down then be destroyed in the water without having to come in contact with something.

[ravens_hawk]

That would be true if not for a couple of things.
A) Even when entering at an angle of say 23 degrees (what they used in the show) it is largely just hitting the tip of the bullet. To use your diving analogy it would be like taking a long dive, even though you're entering the water at an angle its still only your hands breaking the surface tension.

B) The test that have been done on flesh (which show the same results) are done at a 0 degrees, or as close as can be done with bullet yaw.

[Harrm]

If the resistance of the waters' surface tension is enough to strip a round, it's enough to strip it no matter the angle it comes in at. Also, think about this: water does not have a solid form. It is very likely that the bullet will never, ever, ever strike a perfectly flat surface of water, as water has small wakes that change the form of the mass.

Also, we are discussing ballistics, not aerodynamics.

--Harrm

[Clutch]

If the resistance of the waters' surface tension is enough to strip a round, it's enough to strip it no matter the angle it comes in at. Also, think about this: water does not have a solid form. It is very likely that the bullet will never, ever, ever strike a perfectly flat surface of water, as water has small wakes that change the form of the mass.

Also, we are discussing ballistics, not aerodynamics.

--Harrm


water has a solid form..... it's called ice :D lol

[geogob]

so many ballistics experts o_0

That's all I'll say for now!

[Harrm]

Haha...

--Harrm

[tomcat ha]

so many ballistics experts o_0

That's all I'll say for now!

Says something about the geek factor in the inf community.

[Burger]

and it's aquadynamics, not aerodynamics.

[ravens_hawk]

Fluid dynamics. Aquadynamics is not a word.

[[UMC]Boron]

..oh snap

[Harrm]

It's not Fluid dynamics until it enters the water.



...lol aquadynamics.

--Harrm

[ravens_hawk]

Fluid dynamics
"The branch of applied science that is concerned with the movement of gases and liquids."
Fluids are gases and liquids. (Thus while in the air fluid dynamics apply.)

[Harrm]

Oh. Aerodynamics is a branch of Fluid dynamics. My bad.

--Harrm

EDIT: Reading further, technically we're both right. You're just more right. You get a gold star.