It is balanced near the middle on the wooden support. Air is supplied via the hose to a port by the gage, visible on the right. Inside the barrel, all the way back, is a piece of ethrafoam with peanut butter smeared on it. The weight of a squirrel is enough to cause the whole thing to tilt slowly clockwise until the plenum hits a switch mounted on the right end of the base. This triggers the lawn sprinkler valve, the green object between the barrel and the air plenum, launching the little rodent far, far away.
Note to any budding mad scientists out there: A 24 VAC sprinkler valve will work just fine on 12 VDC. The cordless drill I use is a $10 (on sale) Drillmaster unit from Harbor Freight. It is 14 or 18 volts, depending on the vintage. If you run the valve at 18 VDC for extended periods of time, you will burn out the coil. Short time use is fine. The sprinkler valve is rated at 120 psi. The Spears company will tell you to never put compressed gases into its PVC tubing. Over time the oil that goes with the compressed gas will degrade the PVC, and it WILL fail. You've been warned.
5 comments:
Bill, that is just evil.
I like it.
/me used to have a potato cannon.
did you ever get one? how far did he go and were there survivors/did he come back?
I love the basic idea. . .
It didn't work as such, but I'm not ruling out the production of a launch video later this year. See the various posts above on the topic.
The problem is that the inherent slow leakage of the sprinkler valve caused the compressor to run too ofter, annoying the wife.
This means that I'll have to catch one using the pipe and bucket rig described above, but without the water, and launch him personally.
Film at 11, whenever 11 turns out to be.
A thought on the compressor issue (and now that I think about it, the tilting, too.)
Use a cheap motion sensor--like the kind for floodlights, but instead of turning on a light, it turns on juice to the pump. Also, a few electric timers and you could automate the whole operation, based off when the squirrel enters the barrel, or even better, *after* it enters the chamber. A small hole alongside the barrel, tape over the sensor head except where the hole is, and viola!
One other thing... do you have to launch them into the stratosphere, or is there a suitable target... like a sheet of plywood or a brick wall nearby?
Launching them straight up is certainly photogenic, but launching them into the fence insures they won't be back.
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