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C:B ratio on my Cannon! :(

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
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C:B ratio on my Cannon! :(

Unread postAuthor: CannonCreator » Fri Aug 17, 2007 9:08 pm

Ok first of all, this is the C:B ration on my FIRST cannon. I didn't have rat calc before this. And even worse I used the instructions in the BACKYARD BALLISTICS book, which abveously didn't have the correct meusurments. Ok theae are my cannon mesurments.

Chamber- 4" sch40 diameter, 15 inches long

Barrel- 2" diameter, 36 inches long

So my C:B ratio is____________ 1.61:1 :shock:

to make me C:B ratio 1.00:1 my barrel needs to be 57.75" rounded to 58"


I have threads on my chamber so I can switch out barrels. If I were to go out and make a barrel long enough to make my C:B ratio 1.00:1 WOULD IT BE WORTH IT? Will it make a big difference?
:?: :?:
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Unread postAuthor: hi » Fri Aug 17, 2007 9:41 pm

yea it should be a decent power up grade. it may get 100 fps or so more is my guess. i'd do it if i were you.
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Unread postAuthor: CannonCreator » Sat Aug 18, 2007 1:03 am

Thanks,

Is there any more Opinions?
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Unread postAuthor: Modderxtrordanare » Sat Aug 18, 2007 1:46 am

.7 or .8 to 1 would be an even better C:B ratio. :)
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Unread postAuthor: jimmy101 » Sat Aug 18, 2007 1:09 pm

Read the SpudWiki page; http://www.spudfiles.com/spud_wiki/inde ... rrel_ratio

Image
Above is a graph of velocity versus C:B ratio for a particular gun. Notice that this particular gun's performance at a 1.5 CB is really crappy, roughly half the muzzle velocity that it has with a CB of 0.8. That is a factor of four in the kinetic energy of the projectile.
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Unread postAuthor: CannonCreator » Sat Aug 18, 2007 2:59 pm

ok so 1:0.60 is for optimal performance?



1:0.60 right isn't that what 0.60 means?
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Unread postAuthor: MisterSteve124 » Sat Aug 18, 2007 5:35 pm

No need to post again. As you can see that won't get anyone to respond quicker. It means that the best C:B ratio is 1:0.6 according to that. But keep in mind that is using a regulated propane set up. So you may want to go higher.
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Unread postAuthor: CannonCreator » Sat Aug 18, 2007 5:43 pm

K, But on rat calc The barrel ratio always stays at 1 dosn't it?

Becuase I cant make the barrel ratio budge, only the chamber ratio
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Unread postAuthor: MisterSteve124 » Sat Aug 18, 2007 5:51 pm

Yeah I just figured out I switched them after I posted. My bad it's .6:1
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Unread postAuthor: CannonCreator » Sat Aug 18, 2007 9:56 pm

0.60:1 CB ratio???
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Unread postAuthor: Mishkan » Sat Aug 18, 2007 10:13 pm

Your chamber is 60% of what your barrel is...
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Unread postAuthor: CannonCreator » Sat Aug 18, 2007 10:44 pm

I know what it means, but isn't the barrel a little long in that sense?

Thats a huge lose in momentum it seems like
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Unread postAuthor: frankrede » Sat Aug 18, 2007 10:55 pm

CannonCreator wrote:I know what it means, but isn't the barrel a little long in that sense?

Thats a huge lose in momentum it seems like
Momentum?
Longer barrel=More power(at least till a point)
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Unread postAuthor: MisterSteve124 » Sun Aug 19, 2007 9:13 am

You could just make ur chamber a little smaller and not have to make your barrel really long.
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Unread postAuthor: CannonCreator » Sun Aug 19, 2007 10:31 am

Ya its jsut hard, becuase I love BIG chambers and SMALL barrels :(
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