Combustion/pnematic?

[lukemc]

i was designing a new combustion cannon it was an over under design with propane injection chamber fan you know "the works" and then i thought if i added a shrader valve a psi gauge and a butterfly valve i could have it work eather pneumatic or combustion. i could use the pneumatic for distance and the combustion for fun. would this work or did over look some detail. please tell me if i could do this

lukemc

[risto]

i had a similar idea but mine was to have my propane set like a quick-disconnect and so i could switch quickly between combustion and pneumatic. I didn't do thru with it because i couldnt find a butterfly valve and i couldnt find a real easy was to vent the chamber after i shot from combustion. If you feel like you have the money and know-how, go for it and post the results!

[lukemc]

wow i just looked up a 2" butterfly valve there expencive!! as for clearing out the barrel how about a threaded end cap and a chamber fan...can threded end caps hold pressure? i think i would use a sprinkler valve im not sure how to keep it open durring a combustion shot though

[risto]

i highly doubt threaded end caps can hold pressure very well. It seems like they would need to be wrapped in teflon tape or something anyway to make them even seal properly.

[ArticWolf]

Mabe you can add the best of both worlds together and reserch a little bit to make it a hybrid. Get some sch 80 pvc (pressure rated), metered propane and a way to add air pressure. If I had the money and a way to get sch 80 pvc I would do it, you get both distance and fun for the price of one but this is just an idea but you never know. Burst disks are easy to make but like I said this is just my Idea have fun thought

[lukemc]

i thought about a hybrid once but they always seemed way out of mu budget and building level

[VH_man]

Is it possible to make a combustion that DOESNT leak the pressure? where you meter the right amount in, ignite it, then the pressure created its released with a valve? i think you could get good power outta that.......... kinda dangerous though. it would have to be steel because containing the combustion gasses in PVC will basically make a Fragmentation Mine............

[lukemc]

probly not because the pressure created by a combustion maxes at 80 psi but all the pressure at once could be dangerous even though the pvc is rated at higher

[sandman]

i dont understanting what your talking about, can you sum it up about the not leaking pressure

[judgment_arms]

If you want a cannon that could be shot ether as combustion or pneumatic then make a coaxial.

[frankrede]

Well is you enclosed teh combustion you have a high chance of your fittings blowing or the pvc degrading.
why not make a female connection on your chamber:barrel port and have the option to add a union,sprinkler valve, etc.
That would make your cannon versatile and upgradeable.

[homeflake210]

Instead of getting a butterfly valve maybe you could use cam locks and a sprinkler valve for fast switching between pneumatic and combustion.

[lukemc]

a detachable valve would work except is it posible for a threaded end cap to hold pressure

[homeflake210]

Yes, a pressure rated female adapter and a pressure rated plug will hold pressure just fine (with teflon).

[lukemc]

cool i might just make this. ill post it when im done