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Barrel & Chamber Ratios
Posted: Tue Oct 31, 2006 11:00 am
by silentfox_02
Hi I have not built a cannon and am going to start I am going for a 10' cannon and want to know whats a better & efficiant ratio
7' Barrel and 3' Chamber
6' Barrel and 4' Chamber
any others?
Posted: Tue Oct 31, 2006 2:07 pm
by joannaardway
It depends on your chamber and barrel diameters, and your fuel.
So: What ID (internal diameter) are you going to use for your chamber/barrel
And: what fuel are you going to use?
Oh yeah - don't ever use hairspray. It gunks up the chamber. Use a different spray instead (but not one that can damage the plastic), or propane.
Posted: Wed Nov 01, 2006 11:35 am
by silentfox_02
probably 2.5" barrel and 3" chamber I dont know what fuel but what I am asking is what should I use for C:B
Posted: Wed Nov 01, 2006 11:50 am
by joannaardway
If you are using a spray can, then you'll need a chamber about 1.5 times the volume of your barrel.
If you are using metered propane, then having a chamber about .8 times the volume of your barrel is more efficent.
As this is a ratio, the common factor of pi can be expelled from both of the volume equations.
Posted: Wed Nov 01, 2006 6:51 pm
by SpudBlaster15
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Posted: Thu Nov 02, 2006 11:32 am
by silentfox_02
I guess I will go with 7' barrel and 3' chamber with diameters of 2.5" for spuds and tennis balls and 3" for the chamber only question is where do I get the pvc, like what store? will they let you buy if they know it is for a cannon?
Posted: Thu Nov 02, 2006 12:08 pm
by reaper613
i say do the 4' chamber, worst case you end up extending the barrel after you see how far your projectile goes and realize you can make it go farther. i mean the only thing better than a 10' cannon is an 11' right?
Posted: Fri Nov 03, 2006 2:51 pm
by silentfox_02
you mean 7' barrel and 4' chamber?
then where can I buy the pipe what kind of hardware store
Posted: Fri Nov 03, 2006 2:59 pm
by SquishY
Try Lowes and Home Depot, I have the luxury of a really cheap plumbing supply house near me.