Additional questions about improving pneumatic catapult

[hrench]

Originally Posted by tr6scott

This is a problem, to get a fast reaction time, you need to have cylinders at the bottom of the stroke. So this is a problem if you are not using a latch and pre-pressuring the cylinder prior to launch.


If you go with the latch method, they that volume of air in the cylinder, is basically a low pressure storage tank, which would be beneficial to that system.

I'm on the other side of this--I think there are two ways (at least) to make a pneumatic catapult work and the one my team used is to not retract the cylinders the whole way and instead fill the cylinders 'chamber' to 60 psi while the catapult is latched. If you simply hold down the catapult with your hand while these fill and then release, you'll see how that would work.

The other way is what tr6scott is talking about, it would be to use small diameter cylinders and lots of stroke and large Cv valve, hoping to get enough travel to get speed.

Since you have large diameter cylinders, I think you need to stick with the first plan. You need a latch. The tractor-supply gate latch will work fine, but if you want simplicity and no failure, I recommend you put a small piece of steel on the end of the catapult and hold it down with an electro magnet. The one we use is rated at 180 lbs of pull and uses 5.6 watts.

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Also, I think your current catapult arm is too heavy. We use PVC. Really. Just clamp it with u-bolts---don't drill holes in it.

I don't recommend three cylinders--recovery time will take too long using that much air.