SpudFiles

I really wanted to test this before anyone I posted it, but I guess I'll go ahead and ask about it. Would a burst disk about 1' in front of a piston valve (or any valve) increase the power? In theory it seems it would. Because the air would have a little more time to conjugate in one area, and release all at once. Use a burst disk that is rated a little lower than the pressure you have in the chamber, and it should release with maximum power. I am going to test this soon and I will post the results afterward. I'll test with a normal barrel at one PSI rating, and then with a burst disk with the valve. Afterward, I'll try a few other PSI ratings and compare all of them to see if it is truly increasing power.

I think you are on a winner there, i think it may have been tried before though. JSR used a piece of sticky tape as a burst disc one of his wittle guns and achieved 1104 fps. (was at 400 psi).

Yes it might increase power a bit but i think it would burst before all off the air caught up.This has been discussed before but i am not aware of it being tested before.

Well, of course I would try different rated burst disks as well. Who knows what the results will bring. I have a lot of free time on my hands during the week! I'll get results posted asap

It wouldnt be that much better than a plain Piston, but it would make the piston opening effectively be slightly faster. This would matter on a short barreled gun, but if you have much length of barrel, which i assume you will, since it seems you are going for power, then it won't have much effect at all, because over a longer distance the opening speed of the valve has much less of an effect.

edit: sorry about that double and tripple posting, I fixed it. My connection to Spudfiles frose, and it sent the post 3 times

It's cool, I didn't even notice. And yeah, I have thought about the barrel length. I think I will test it on a 3' x 2" barrel and see what that brings me.

Another way of doing this would be to have the barrel tighter around the breech, creating more friction with the projectile meaning the latter will take longer to accelerate, giving the piston more time to open fully.

True. Another simple yet very effective idea. Is there a thread in the how to about tips for pneumatic guns? If not, I should start one. If anyone wants to send in tips about making your spud gun more efficient, please PM them to me. (sorry, pneumatics only, I'm not a big fan of combustions, though my very first gun was one, :/)

Is there a thread in the how to about tips for pneumatic guns? If not, I should start one.

There should be a simple list of design features (an Idiots guide) and the effect on performance.

For example, longer barrel -> more velocity, less noise

bigger chamber -> more velocity, more noise

bigger pilot volume -> slower opening valve, less velocity


etc.

jackssmirkingrevenge wrote:Another way of doing this would be to have the barrel tighter around the breech, creating more friction with the projectile meaning the latter will take longer to accelerate, giving the piston more time to open fully.

I'm going to try that on one of my mini-combustions, thankyou kind sir

okay make it tighter at the breech, so like line the breech with an epoxy layer
or how about hopup