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| silentfox_02 |
 Posted: 10/31/2006 11:00 AM Post subject: Barrel & Chamber Ratios |
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Private
Joined: 31 Oct 2006
Posts: 5
1.27 Spud Bux
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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? |
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| joannaardway |
| Posted: 10/31/2006 14:07 PM Post subject: |
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Brigadier General
Joined: 09 Oct 2006
Posts: 961
115.90 Spud Bux
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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. |
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| silentfox_02 |
| Posted: 11/01/2006 11:35 AM Post subject: |
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Private
Joined: 31 Oct 2006
Posts: 5
1.27 Spud Bux
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| 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 |
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| joannaardway |
| Posted: 11/01/2006 11:50 AM Post subject: |
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Brigadier General
Joined: 09 Oct 2006
Posts: 961
115.90 Spud Bux
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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. |
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| SpudBlaster15 |
| Posted: 11/01/2006 18:51 PM Post subject: |
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Human blast shield
Joined: 18 Oct 2006
Posts: 1539
11.03 Spud Bux
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If you are talking about fixed chamber volume cannons, I wouldn't tie a specific ratio to aerosols in general. Obviously different sprays contain different chemicals which will have different energy densities, and will thus require different barrel lengths to harness all of the energy without creating the friction associated with the completion of combustion before the projectile has left the barrel.
With a fixed barrel launcher, a larger chamber will obviously give you higher levels of performance given any propellant, to a point.
When using aerosols, I find it best to make an overly long barrel, then cut it down until I get the desired performance level. I find that a 1:1 ratio works best on fixed chamber cannons using starting fluid. |
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| silentfox_02 |
| Posted: 11/02/2006 11:32 AM Post subject: |
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Private
Joined: 31 Oct 2006
Posts: 5
1.27 Spud Bux
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| 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? |
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| reaper613 |
| Posted: 11/02/2006 12:08 PM Post subject: |
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Corporal
Joined: 27 Feb 2006
Posts: 74
2.83 Spud Bux
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| 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? |
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| silentfox_02 |
| Posted: 11/03/2006 14:51 PM Post subject: |
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Private
Joined: 31 Oct 2006
Posts: 5
1.27 Spud Bux
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you mean 7' barrel and 4' chamber?
then where can I buy the pipe what kind of hardware store |
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| SquishY |
| Posted: 11/03/2006 14:59 PM Post subject: |
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Master Sergeant
Joined: 07 Feb 2006
Posts: 159
600.49 Spud Bux
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| Try Lowes and Home Depot, I have the luxury of a really cheap plumbing supply house near me. |
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