SpudFiles

hello, i'm planning on building a advanced combustion cannnon using metered propane. and my question is "what's a ideal Chamber To Barrel Ratio for a and advanced combustion"?

i want to figure that out before i go and buy the pvc.

Thank You

There is no such thing as an "ideal Chamber To Barrel Ratio for an advanced combustion" gun.

Read the SpudWiki on combustion gun's CB ratio.

Get a copy of HGDT and fiddle with it. Decide what you want to trade for better muzzle velocity.

These might help:
http://www.spudfiles.com/forums/complet ... t4512.html

http://www.spudfiles.com/spud_wiki/inde ... rrel_ratio

I always use about a 1.5:1. I read that that was the so called "ideal ratio" somewhere, but I could be wrong.

Go to Burnt Lake's Siteand read the performance data gathered on various sized c:b ratios. He found .8:1 was roughly an ideal ratio. However you can go on up to 1.5:1 or so with very little loss of efficiency...which is really what you're measuring.

However, as a general rule of thumb, for any given chamber, a reasonably longer barrel will almost always improve performance AND for any given barrel, a larger chamber will almost always improve performance to some degree.... 8) Did that make sense?

So it really boils down to a compromise on size and weight and handling of the gun you want to build.

Only drawback on larger chambers is that burn time may increase, so multiple spark gaps would surely help.