Nerf Air Restricter like Piston Valve

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Thu Aug 06, 2020 11:55 am

Hello Spudders,
Please excuse my ill knowledge of the website - First post (however onto forth cannon so I have some experience)
I have searched what I could with no success, not quite sure how to word it to begin with, the title is the best I can do.
- Basically have a spring retained valve within and inline with the barrel between the chamber and projectile.
- The spring should be strong enough to resist chamber pressurization.
- Once ignited the pressure will overcome the spring, allowing for a flash, boom and a spud (Golfball) downrange.

This is obviously very simplistic and would've been tested before but I could not find any documentation.

Does this work?
Or does the piston valve cause more resistance negating the benefits of a pressurized chamber?

I do not own the machinery necessary to deal with Rupture Discs or chamber piston valves.

Thank you all!
So excited to be here.
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Fri Aug 07, 2020 5:19 pm

These types of cannons generate high pressures and have to consist of strong metal construction. PVC or any other plastic will explode.
The concept works. Several of us have built cannons like this with good results. The performance benefit is huge and the spring force doesn't take away from the performance. It sounds like you want to find a valve that you can purchase that will work, but I'm not aware of any that exist. We don't use mechanical springs though. Instead, we use air pressure behind the piston. This way, you can adjust the "spring" force by adjusting the air pressure. We call them "hybrid cannons". You can see my build log below to see how I did it. A standard spudgun shoots a golf ball around 500fps I think and the one I made does just over 1000fps. Mine is a conservative cannon though, so the others would have even faster velocities.


Once you see how it works, I suppose you could get creative and try to improvise. Or, you can study the design that others have made with purchasable parts like these below.


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