This is a topic that tests your grasp of several related disciplines,

Question:

Design a gun that has the same offensive capabilities of your regular field firearm, but instead of bullets, it uses water as ammo.

How do you propel water with the same destructive velocity of a bullet?

if you can propel a liquid with such velocity as bullet, why not use it to propel solid object with more mass? you get much more damage out of it.

maybe with decade of research....with certain chemical reaction added ....mmmm....hehe

just a cylinder containing water with a piston on one end and the other end built with weak material. behind the piston put some explosive and you are good to go. since water cannot be compressed it can penetrate any object as long as it has a high enough velocity.
the only problem is distance. since water changes its shape, it loses it's aerodynamic properties once it leaves the cylinder and accuracy and energy is rapidly lost.

http://en.wikipedia.org/wiki/Water_jet_cutter

to avoid leaving solid evidence behind?

and it vaporize due to absorbing thermal energies from the explosion

Similar thing like you're trying to fire an ice bullet

why yes, but there's the issue of portability too

erm.....i lazy to draw....


difference with the ice bullet is complete separation with blast chamber by a piston and higher volume of water.

edit: pic removed due to noobness in drawing


This post has been edited by slimey: Mar 20 2010, 11:56 PM

the simplest but still not very small (and very dangerous) is to use a railgun method of acceleration. of course you need some metal (like a small pin) to be in the ice, but after that, ur good to go.

the thing is due to terminal velocity and normal drag force applied by the ice surface, the range of the bullet wont be far.

but what if it was very impure water, like some substance holding the water together, imagine those small jelly water balls travelling at 300m/s. they hold shape better. and they definitely dont leave a damn trace.

bit of calculations : max initial velocity of a 4mm jelly ball. (rough est.)
=sqrt((2x9.81x)/(1.184x4xPix0.004^2))
= 287.03 m/s
~bout 260-270m/s (max initial velocity) after taking into account drag constant.

so, it can travel bout... (yadda yadda yadda..) ~ 0-20 meters effective range. (kinda near right)

hmm... so. all we need is an explosive behind it and 'water shotguns' will be a reality.

Air guns would work well too, but speeds will only reach about 140m/s. basically same principle as paintball gun.

This post has been edited by rafazafar: Mar 21 2010, 02:31 PM

how about instead of a solid piece of metal in the ice, metal dust mixed evenly into the ice?

that could work actually, but we need to apply the railgun method.. huhu. kinda interested in making one actually..

i think it is more likely to be trace back to the killer, since such high tech weapon will be expensive and only small number of manufacturer able to made then. while guns and bullet are every where.

This post has been edited by robertngo: Mar 21 2010, 02:30 PM

very true, you probably have to make it yourself and dismantle it immediate after usage n find somehow to hide it.

Ice bullets would do.

maybe pykrete would work replacing a bullet in a normal gun

This wouldn't be easy to do, sounds easy but not. You need the metal to stay in a very well disperse form as metal is very dense compare to water and tends to sink to the bottom before the water get frozen. To achieve this, you need, extremely fast freezing which is not easily achieve and the process would be costly as you'd need to source out the correct chemicals to do so (something like liquid nitrogen?) and a very good insulating vessels.
The other method can be done is through solid-liquid colloidal suspension, which you need to source the correct surfactant for it and grinding of the metal to very fine dust, which...is more or less as difficult as the former method.


And ...

If the purpose of making such weapon is to eliminate any traces after using it, then adding any substance into the water to enhances it physical resistance to heat and impact would not be ideal as those substances would become uncommon and more likely lead to getting trace back after all plus the process of sourcing out the apparatus and chemicals to do such a weapon makes you even easier to get trace back, which is not ideal at all. Might as well use a normal gun.

if it was to cause as much damage as hollow point bullet, i should shatter on impact thus causing massive damage to organ.

anyway using exotic weapon will not be ideal if you want to hide your identity, you are more likely to be track down then a black market or stolen gun.

Laser gun.

I don't think you can use the water similar as a bullet. Even if we manage to shoot it out of the gun at the velocity of a bullet, i think it will get heated and evaporate before it reaches the target.

This post has been edited by pheonix71: Mar 23 2010, 03:43 PM

issue is to leave no evidence such as yr dna/fingerprints behind? hmm..

1. use water gun, but instead of normal water u use deadly poison which as soon as it touches the skin, dead!

2. use metal bullet. but instead of it going in a piece, make it :

2.1 so hot that it penetrate the skin
2.2 make it disperse .. but the bullet disperse as soon as it touches object..and the bullet better be sharp..
got it?

who mentioned about leaving fingerprints or dna behind???
a person shot by a gun would leave behind a dead body with or without the bullet in it, plus bullet wound.


hmm so far nothing that deadly to cause instant death.



isn't the purpose of bullet is to penetrate? how does temperature affect it? plus the bullet can still be traced back to the gun that fired it.

to avoid tracking, use the bullet that dispersed .. into smaller bits that's impssible to track.

There's isn't such a substance known as 'deadly poison'. Poison kills because u consume it or comes into ur body, not touches, neurotoxins is the cloeset thing. The worst thing you can get is highly corrosive material that will not kill but burn you.

Bullets are already hot as soon as it exist the gun as it absorbs thermal energy from the combustion.

U meant fragments? Something like shotgun? If it's so fragile that it breaks into fragments as soon as it hits, then it wouldn't be very much lethal

Do you even know what is disperse? >_>

Impossible to track? Do you have any idea how sensitive today's instrument is? Metal for instance can be easily track by using AAS even at mmolar range. Some other inorganic qualitative test using chemicals is already sufficient to detect it.

So u might say, so what if they detect metals? It could be something else.

Okay then electron microscope, giving magnification of up to 1000x of your naked eye.

This post has been edited by NicJolin: Mar 24 2010, 08:55 PM

if u put metal ball inside the ice.. and during the firing wouldn't da heat generated melt the ice.. railgun used megawatt, imagine the heat produce by it

to project water at such speed of destruction is probably conceivable with at least 10,000psi. that too you need a big pump to generate enough pressure to do so with current technology.

perhaps lazer projector that does as well as bullets would be a much better option.

heat from railgun can be negated by the system, but still pumping in mega amps isnt easy.
, another way is actually a system that can launch a bullet or something way up into the air and acts like an artillery.

put seriously laser isnt a bad idea, a very super efficient reflector can do the job of focusing and killing.

as have mentioned earlier why water would make a better alternative because it leaves no trace behind. laser is definitely the best at doing just that. and also no recoils to render the accuracy of the shot too.

Isn't this going off topic?
The original question is how to make a gun that fires "water" as ammo.
"How do you propel water with the same destructive velocity of a bullet?"
Nothing about leaving no evidence of the shooter whatsoever.

thanks for the pointer. why not you do the job rerail back the topic?

Because I believe the answer lies more in the area of mechanical, thermodynamics and chemistry non of which is my area of expertise.
But here's my general idea,
1. To send any projectile over any distance and having the same destructive velocity of bullets over the air requires the projectile to have some kind of stable mass. Water is liquid form doesn't seems plausible to me so I would go with ice, or would superheated plasma and/or ionized form has any uses? Just wild guess here.

2. The idea is to propel the "ammo" to very high velocity. Common guns uses gunpowder to generate the explosive pressure required. Note that heat in this case is simply a side effect. So either we shield the "ammo" from the heat, or look for other mechanism to generate the required pressure. Compressed air, jets of water, or would repelling magnetic force, power requirement aside, all sounds plausible.

Rail gun sounds like a good choice, except pure ice is a very poor electricity conductor. So perhaps mixing it with the appropriate amount of chemical ions and it would work.

Ice might work, but not pure water. Ice that added with solutes, something like an organic thickener and electrolytes could enhances its resistance to the thermal energy and increases its melting point and boiling point. The chamber which the combustion take place should be lowered in terms of pressure, as this could lower the tendency of ice turning into water. Remember, water is denser than ice.

I think the keypoint is to ensure that the ice stays intact the moment it leaves the chamber.

This post has been edited by NicJolin: Mar 27 2010, 11:51 PM