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combustion marble gun....

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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combustion marble gun....

Unread postAuthor: nightshot » Thu Jan 03, 2008 7:41 am

I want to build a marble rifle, but I don't have a compressor, and I want to make a combustion, so I have 2 questions... Is it safe ?? How much meters the marble can go ??
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Unread postAuthor: Hubb » Thu Jan 03, 2008 7:44 am

Yes

It depends on the setup, C:B ratio, fuel, fuel / air mix, etc.
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Unread postAuthor: jackssmirkingrevenge » Thu Jan 03, 2008 7:46 am

If you can make something like this with a barrel suitable for marbles you'll be fine, as to range it depends on the variables hubb017 mentioned, but the bigger you make it the better.
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Unread postAuthor: nightshot » Thu Jan 03, 2008 7:57 am

Specs:

Combustion Chamber = 7cm x 45cm
Barrel = 3cm x 90cm
C:B Ratio = 1:2
Propane powered
With a Computer Fan on chamber ...

If this specs are not good please tell me ;D
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Unread postAuthor: Hubb » Thu Jan 03, 2008 8:24 am

Some have said that to make an efficient combustion, one would need a ratio of around .8:1. Also, is there a computer fan that small? I've never seen one and was just wondering.
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Unread postAuthor: TurboSuper » Thu Jan 03, 2008 9:28 am

Yeah, a standard fan is 80mm, and they go much smaller.

Anywho, i'd reccomend a .8:1 for a propane-powered one.
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Unread postAuthor: nightshot » Thu Jan 03, 2008 9:48 am

well, can you recommend me a good setup for my cannon with at least 150cm of Length please... =]
thx
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Unread postAuthor: Hubb » Thu Jan 03, 2008 10:44 am

I don't feel like doing math right now, but the RatCalc should be able to help you. Also, the rest of Burnt Latke's site may be able to answer any othe questions you may have. If not, we can.
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Unread postAuthor: jimmy101 » Thu Jan 03, 2008 1:11 pm

nightshot wrote:Specs:

Combustion Chamber = 7cm x 45cm
Barrel = 3cm x 90cm
C:B Ratio = 1:2
Propane powered
With a Computer Fan on chamber ...

If this specs are not good please tell me ;D

Chamber volume = Pi(r<sup>2</sup>)L = (3.14)(7/2)<sup>2</sup>(45) =1730 cm<sup>3</sup>
Barrel volume = Pi(r<sup>2</sup>)L = (3.14)(3/2)<sup>2</sup>(90) = 635 cm<sup>3</sup>
C:B ratio = 1730/635 = 2.72

The chamber is way too big for the barrel.

Perhaps drop the chamber to 25cm and increase the barrel to 150cm.
Chamber volume = (3.14)(7/2)<sup>2</sup>(25) =961 cm<sup>3</sup>
Barrel volume = Pi(r<sup>2</sup>)L = (3.14)(3/2)<sup>2</sup>(150) = 1060 cm<sup>3</sup>
C:B ratio = 961/1060 = 0.9
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Unread postAuthor: TwitchTheAussie » Thu Jan 03, 2008 6:31 pm

Cough nerd cough :lol: . Yeah mate the ratcalc can help you heaps trust me. But if ya wanna do things the easy way, try the water method. Block one end of the pipe to be your barrel, fill your chamber with water and tip it into the barrel. Minor equations can be used to get you .8:1 ratio
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Unread postAuthor: f.c » Fri Jan 04, 2008 7:01 am

look up the amc made by me. its a combustion powered marble gun.
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Unread postAuthor: Pyro Ninja » Fri Jan 04, 2008 7:34 am

I believe "experiment_u2" made a nice combustion marble gun.
Its called the "famas combustion"
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Unread postAuthor: ALIHISGREAT » Fri Jan 04, 2008 7:37 am

Pyro Ninja wrote:I believe "experiment_u2" made a nice combustion marble gun.
Its called the "famas combustion"


dude thats one sick looking cannon, dead space could have been a problem but i see he used a burst disc which would counteract the dead space.
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