- Darin McGrew
- Pine Head Legend
- Posts: 1748
- Joined: Fri Jul 18, 2003 1:23 pm
- Location: Mountain View, CA
I've seen water rockets made from soda bottles fly pretty high. Here's the basic design:
Obtain a bunch of bottles. The kids can attach fins, nosecones, etc. with duct tape.
You'll also need:
- a cork that fits snugly into the mouth of the bottles
- a ball inflation needle
- an air compressor
Cut the cork so it is short enough for the ball inflation needle to go all the way through it lengthwise. Drill a hole through the cork and insert the ball inflation needle through the cork through the hole. Clamp the valve end of the compressor hose to the ball inflation needle. It should look like this:
Next, build a small wooden stand. It should look like a bench with a hole in the top. The hole in the top should be sized so the bottles can be relatively stable when they stand in it (mouth down), but so the bottles can fly upwards without interference from the stand.
Put a small amount of water in a bottle, then place it on the ground (mouth up). Place the upside-down stand on top of the bottle and insert the cork into the bottle's mouth. It should look like this:
Finally, turn the stand and bottle over, and turn on the air compressor. It should look like this:
When the pressure inside the bottle exceeds the force holding the cork in the bottle, it will launch!
- Stan Pope
- Pine Head Legend
- Posts: 6888
- Joined: Sat Jul 05, 2003 7:01 pm
- Location: Morton, Illinois
A bicycle pump with a 1" diameter piston allows a "cub scout" sized person to launch to heights of 70+ feet with moderate effort. A cub scout weighing 40 pounds should be able to inflate to pressures of nearly 40/(pi*(1/2)^2) psi, if I remember the math right.
A cup of water is sufficient for an unadorned rocket. Add weight to the rocket body (fins, basket to carry egg-stronauts, etc) and a bit more water should be helpful. Here is something that we did to add spice to one
Day Camp noon-day program, utilizing the launchers.
"If it's not for the boys, it's for the birds!"