SpudFiles

Hi, I'm a 5th grade teacher trying to make a cheap paper rocket launcher with all metal (safe). I'm wondering how to make an electric sprinkler valve open, then close quite quickly, so I can get the burst of air, but not lose all the air in a large chamber?

Here's why...
Basically I'm thinking of coming straight out of the air compressor to an adapter fitting, then sprinkler valve, then launch tube.

By doing this there's no plastic as a weak point, electronic trigger for the kids to launch with, etc. What do you think?

PS I've searched for hours to try to find out if these valves will close quickly under pressure, to no avail.
Thanks!

Like a pulsed output ? I have a solenoid valve on my next project so will be interesting to see if I need a pulsed output for that. Going to try a simple switch first, if I need a pulse I'll probably try a 555 timer circuit and a potetiometer to adjust pulse length/power

Honestly since you're not really in need of consistency, a simple momentary switch on the solenoid valve circuit pressed quickly is probably enough.

I was wondering if that would work. So when the button is pushed, it is letting the air out and when you let go it stops? I'll have to give it a try. Thanks!

aaronwhiting77 wrote:I was wondering if that would work. So when the button is pushed, it is letting the air out and when you let go it stops? I'll have to give it a try. Thanks!

At low pressure it mite work but typically when used as a main or firing valve the air just dumps to fast. You said "paper rockets". What are the build details? If you don't mind saying.

Welcome to Spudfiles. :bigsmurf:

Teaching a Spudgun Building class, nice

Thanks for the welcome. I first saw the rockets at a boy scout camp. They took a paper and rolled it around a piece of 1/2" pvc and tape the paper to itself to make the fuselage. Then fold the paper over on top and tape it for a makeshift nose cone. Then make a few paper fins. They had a piece of 3" metal pipe with caps on both ends for the air chamber. It housed a Schrader valve and a reducing tee in the middle that held a 1/4 turn valve to dump the air and, of course a 1/2" pvc pipe for the launch tube. They Added 90 lbs each time and the boy would slam the valve open to launch his rocket. They went up to 200ft.
After looking parts up I found the 3" metal pipe and fittings to be WAY too expensive. Also, thought it would be great not to have to refill the chamber each time.
What do you mean by the valves dumping too fast? Even if the circuit is closed quickly, does the valve just not close fast enough?

Consider something smaller than a sprinkler valve in order to limit flow, easier to hook up to a compressor and it should re-close faster too.

Awesome. Thanks for the advice and for your time. I'll give it a try!

The simplest thing is to entertain an air storage chamber, the amount you want to use at each launch. This camera has to have a stopcock at the entrance, where the compressed air enters from your compressor, an equal stopcock, at the exit, which is the one you will open for shooting. In this way once the camera is loaded, you will have full control over the amount of air ejected at each launch.
The action is as follows:
With the outlet valve closed, open the inlet valve until the set pressure is reached. Then, close the inlet valve, and upon opening the outlet valve the machine will be thrown. I hope you understand. Good project