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20oz Coke Bottles

Post about things you have launched or thought about launching. Also post about various materials used for building cannons. No posts about explosive projectiles!
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20oz Coke Bottles

Unread postAuthor: Hoosier Daddy » Thu Nov 09, 2006 7:28 am

(First post ever)

WARNING: The following text is for informational use only. Building one of these devices could get you invited to the Graybar Motel.

Several years ago, a friend and I were pondering the idea of using 20oz Coke bottles for a pneumatic mortar. For long range, stability of the bottle would be key. Here's what we came up with.

Using a 20oz Coke bottle as the main body of the projectile, cut a length of 1" PVC pipe roughly 6” long. Tap the ID on one end, and thread it onto the bottle, in place of the bottle cap. The opposite end of the PVC pipe would be cross cut to allow for fins to be glued in. Nice and simple. The only hard part is the threads on the ID of the 1" PVC pipe. My friend, being a machinist, made a tap for the PVC pipe. The tap was made from crap steel (cold rolled, 12L14). It worked perfectly!

Now as for weighting the bottle, we took this idea and ran. At the fin end of the PVC pipe, the pipe would have to be sealed off COMPLETELY!!! The area between the fins and the threads no becomes a barrel for a slide hammer of sorts, a C-cell battery in this case with the positive end pointing toward the bottle. The bottle itself can be loaded with your favorite propellant (gas was our first choice). Then place a 12 gauge shotgun shell into the bottle. The rim of the shell will keep it from falling all the way into the bottle. The shotgun shell MUST be glued and completely sealed.

As for a firing pin, a round foam plug and a dulled up furniture tack. The foam plug needs to be the same size as the ID of the PVC pipe. The tack is pressed into the center foam block so that the point of the tack is aimed at the primmer of the shotgun shell. It's important that the point of the tack DOES NOT poke through the foam block!!! The foam block should also be glued in-place to keep it from moving during transport or launch.

A C-cell battery is placed into the 1" PVC pipe and the pipe is screwed onto the bottle. A small hole needs to be drilled through the PVC pipe just about the battery. This is for a safety pin as it keeps the battery from striking the tack, pushing the tack through the foam block and into the shotgun primmer.

Theory of operation... From a ground mounted mortar, place the round into the barrel. Make sure the safety pin is pulled before doing this. Fire the mortar. When the bottle impacts the ground, the inertia of the battery forces the tack into the shotgun shell, and intern, ignites the gas in the bottle. BANG-WOOF!

Now a question, how far do you think one of these can fly? Having seen reports of pneumatic spud guns firing over 900 yards, I have to think a Coke bottle has a much better chance of going well over 1000 yards.

Your input is welcome

Don
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Unread postAuthor: Potatothunder » Thu Nov 09, 2006 2:59 pm

dam good idea little dangerous but wat the hell
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Unread postAuthor: POS » Thu Nov 09, 2006 6:01 pm

I gues the bottle could explode in the barrel. Dangerous I think. Wouldn't try it. I have a idea of shooting a pressurized PVC home made water rocket from a pneumatic gun. So the rocket is fired pneumaticly, high speed, pressure of at least 140 psi. When it leaves the barrel, I figured out a system that triggers the pressure in the rocket, so it propels the rocket even to e much higher speed, resulting in a higher of further flight.

Recoverysystem is needed, or you can use the rocket only once.
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Unread postAuthor: frankrede » Thu Nov 09, 2006 6:45 pm

Self propelled ammo?
Cough~read the forum rules.
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Unread postAuthor: POS » Fri Nov 10, 2006 6:30 pm

is it not alowed to make or post about self propellant ammo, when it uses the same pressure as a pneumatic, and water as fuel ? There are forums about water rockets you know. They are far less harmless that the things I see here. I made them some years ago, they worked pretty well. Now I made a pneumatic. And just havving the knowledge of both things, I 'd like to combine them. What's wrong with that ?
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Unread postAuthor: Hoosier Daddy » Sun Nov 12, 2006 2:54 pm

My bad. I just logged in and noticed the "no explosives" rule. Sorry about that.

Ok, so fill the bottle full of water and plug it with a wooden dowl, rubber plug, etc. It would be heavier seeing how gas is about 6.8 pounds per gallon, and water is 8.6 pounds per gallon. The whole reason for making such a projectile would be to see what kind of range and repeat accuracy you could get.

As for range, I found 3" OD x .065 wall 6061-T6 aluminum tubing from Aircraft Spruce that is the exact right size for 20oz plastic pop bottles. And the bottle doesn't have to be Coke specific. Sprite, Squirt, and the Faygo brands all have the same outside diameter. Not to mention that ALL of the plastic pop bottles use the same cap thread.

Now to the more gung-ho types, see if you can find a large enough piece of PVC, steel or aluminum that all accept a 2 liter pop bottle. That would make a HUGE bang when fired (the gun that is). Since I live in the mid-west, we have a lot of open fields (corn, soybean, hay, etc.) so dropping a water filled pop bottle 1/2 a mile away has no risks of hitting anything except for deer.

Don
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