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phoenix1002 · 05-02-2003, 03:27 PM

For water bottle rockets, what we used was basically 2 metal hooked arms that were held in place with a u shaped piece of metal. The arms were attached to a metal spike that we shoved into the ground so it didn't kick. Then, we had a rubber test tube cork with a hose that went through the center of the cork and was connected to the bike pump. We shoved the cork into the bottle, hooked the arms over the lip around the mouth of the bottle, and put the u into the arms (there were holes for it). Then we pumped it up, and pulled the u out with a string. We got a 20 oz bottle to go farther than the football field.

If you want to make a spud gun, my suggestion is avoid the explosive variety, and go for air pressure. You don't get the flames, but you can adjust the air pressure depending on what you are shooting and how far you want it to go.

My setup is this:

3 feet of 1.5" pvc (you can go bigger if you want)
1.5" brass ball valve
2.5 feet of 2" pvc
1.5" male and female screw adapters
1.5" to 2" adapter
2" end cap
car/bike tire valve
lots of West Systems 2-part epoxy

I used 1.5" pvc because that was the biggest ball valve i could find. I put screw adapters on the back of the barrel and on the front of the valve so I can alternate barrels (I also have a .5" barrel, and will probably make a larger one for tp rolls). I drilled a hole in the end cap, and put the car tire valve through. I put a metal washer in first, just to reduce the chance of the valve falling out. Then I filled the end cap with epoxy until it was at the same level with the back of the valve. This supports the valve and prevents it from being blown out the back, but you have to be careful not to fill the valve with epoxy. When that was dry, I epoxied the end cap to the 2.5' segment of 2" pvc, epoxied the adapter to the other end and to the valve. Let it all dry at least a day, just so its cured fully. I wouldnt' suggest pvc cement, it breaks easily.

The resulting air cannon should have a 3' removeable barrel and a 3' compression chamber and release valve. The screw adapter also makes it easier to move around... 3 feet versus 6.

I use a bike pump with a built in pressure gauge. 80-90 psi throws potatos a pretty good distance.

My next project will be to make one that uses an electric compressor. I just have to figure out how to make an emergency release valve, so I don't over-pressurize it (I think the breaking point of pvc is about 150 psi).

05-02-2003, 03:27 PM	#13 (permalink)
phoenix1002 Psycho Location: lost	For water bottle rockets, what we used was basically 2 metal hooked arms that were held in place with a u shaped piece of metal. The arms were attached to a metal spike that we shoved into the ground so it didn't kick. Then, we had a rubber test tube cork with a hose that went through the center of the cork and was connected to the bike pump. We shoved the cork into the bottle, hooked the arms over the lip around the mouth of the bottle, and put the u into the arms (there were holes for it). Then we pumped it up, and pulled the u out with a string. We got a 20 oz bottle to go farther than the football field. If you want to make a spud gun, my suggestion is avoid the explosive variety, and go for air pressure. You don't get the flames, but you can adjust the air pressure depending on what you are shooting and how far you want it to go. My setup is this: 3 feet of 1.5" pvc (you can go bigger if you want) 1.5" brass ball valve 2.5 feet of 2" pvc 1.5" male and female screw adapters 1.5" to 2" adapter 2" end cap car/bike tire valve lots of West Systems 2-part epoxy I used 1.5" pvc because that was the biggest ball valve i could find. I put screw adapters on the back of the barrel and on the front of the valve so I can alternate barrels (I also have a .5" barrel, and will probably make a larger one for tp rolls). I drilled a hole in the end cap, and put the car tire valve through. I put a metal washer in first, just to reduce the chance of the valve falling out. Then I filled the end cap with epoxy until it was at the same level with the back of the valve. This supports the valve and prevents it from being blown out the back, but you have to be careful not to fill the valve with epoxy. When that was dry, I epoxied the end cap to the 2.5' segment of 2" pvc, epoxied the adapter to the other end and to the valve. Let it all dry at least a day, just so its cured fully. I wouldnt' suggest pvc cement, it breaks easily. The resulting air cannon should have a 3' removeable barrel and a 3' compression chamber and release valve. The screw adapter also makes it easier to move around... 3 feet versus 6. I use a bike pump with a built in pressure gauge. 80-90 psi throws potatos a pretty good distance. My next project will be to make one that uses an electric compressor. I just have to figure out how to make an emergency release valve, so I don't over-pressurize it (I think the breaking point of pvc is about 150 psi). __________________ I'd rather be climbing... I approach college much like a recovering alcoholic--one day at a time...