SpudFiles

I had an idea to make a electrically controlled torpedo for an ROV I might be building. The torpedo itself is a full, 12 gram co2 cartridge. A simple bolt with a sharpened pin is cocked back and set and is then released by servo actuation. The bolt moves forward causing the pin to pierce the cartridge.

The building materials should include:
3/4 copper pipe & fittings
spring
cocking knob (bolt)
piercing pin (nail, screw)
Bolt (smaller sized pipe, capped on both ends)
Strong servo


It should work, though I'm not sure how well 12 gram cartidges would move through the water.

Any comments, suggestions?

Well I used to get them 12 gram c02's and pop them underwater,basically the rose to the surface,spun on top of the water,and hopped out of the pool.leaving my pool all fizzy,lol,like a giant soda:)

If the servo is'nt strong enough you could angle the locked part of the bolt. Putting fins on it might help it go straight. Good idea though, this could work for a burst disk for a regular pneumatic cannon.

cool idea. i would add fins for stability. getting it to fly stright without going up or down would be a challenge. since the co2 is lighter than water it will go up right out of the tube like frankrede said. the solution is to add weights to balance it in the water. but once the co2 starts to leak out of the cartrage the weightas will pull it down and it still wont go straight.

i would just test different things. try a medium amount of weight. if you got that perfect it would create an arch trajectory under the water.

Thats actually a really cool yet simple idea. If i were you, i would put fins on the nozzle part of the cartridge, that way you have some form of guidance but arent increasing the diameter of the cartridge, i would also angle the barrel slightly downward so that they dont just rise to the top because they will have at least some downward motion.

Great idea though with the servo.

that would be sweet to make one of those and instead of a servo have a trip wire. then put it all in my pool. just weight the cartridge so it cant come out of the water and hurt somebody. that would scare the crap out of my friends seeing something flying under the water creating tons of bubbles!

does nobody see the problems of having a servo under water??? lol j/k

i dont think this is a good idea for a pool, what if it hits a tile hard?

but i love the idea still, i was gonna make a small sub, but i cant find anything to seal my shaft... i made 2 "turbines", each had 3 fans made of bottle caps, with 12 blades

The whole torpedo tube will be inside the ROV and will be sealed at the around the barrel.

Another configuration of this I came up with incorporates a trigger instead of a servo. Hand-held torpedo!


In case your interested, the ROV I'm building is the one from PopSci. It was made by Jason Rollette. PVC construction with 6 bilge pumps for thrusters. http://www.rollette.com/rovrev2/

woa thats pretty cool. thats going to be one mean sub with some torpedos! post some pics when your done

What force is going to make it go streight?Have you ever seen how a bottle rocket with out stabilizators fly?

howabout fins where it gets narrower and shapes into the small nozzle? you will still have a probem with the thing being full of highly pressurized gas under water. alot of air in a small space means it will float to the top very fast.

"you will still have a probem with the thing being full of highly pressurized gas under water. alot of air in a small space means it will float to the top very fast."

Gases "float" since they are not as dense/ heavy as whatever is surronding them. If you compress these gases they get heavier since there "denser". Go toss a empty and filled disposable CO2 cartiage into a body of water and you will see If what you said was true divers would "pancake" the water when they jumped in. Hell at 3,000PSI that means they would be 204 times more "floaty" then regular atomspheric "air". Dont you just love my words I make up?

oh i see. hah i feel stupid now.

Sink test results:

Full cartridge= SINKS!

Empty Cartridge= SINKS!!


The gas inside a full cartridge is well, a liquid! So obviously it's denser than water. With an empty cartridge, the weight of the metal alone is enough to counteract the air inside and still sink. The hole at the top is so small that air doesn't even bubble out.

PVC Arsenal 17 wrote: An empty 12 gram full of gunpowder with a percussion cap on the nozzle would make a sick impact-detonated grenade. Maybe One 12 gram for propulsion with an explosive 12 gram attached to it would make it a mini warhead!

the at would be very angry at you for this, if you check bcpneumatics, these things throw shrapnel like crazy, and are very powerful