A place for general potato gun questions and discussions.
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Urban Ninja
- Specialist 2
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- Location: Sydney Australia.
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Sun Jan 01, 2006 6:10 am
Hi Im new to this site and was just wandering if you could build a combustion spudgun out of copper piping
![Idea :idea:](./images/smilies/icon_idea.png)
? The chamber being 22mm and the barrel 15mm. I know that someone on this site has built the pistol version but Im really looking to build a rifle version.
![Question :?:](./images/smilies/icon_question.png)
Do you think it could even get the projectile out of the barrel? Ive never built a proper combustion before but loads of pneumatic, so i have no idea how to make one.
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boilingleadbath
- Staff Sergeant 2
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Sun Jan 01, 2006 3:41 pm
I understand that often people have trouble getting a proper fuel mixtures in long, thin chambers. I would suspect that the same problem would present it's self with multiple chambers.
So, let's say you put a 75mm long chamber on it (which should be short enough to avoid mixture problems). This means your barrel can be (at most) 230mm long ((22mm^2 / 15mm^2) / .7 * 75mm), for a total launcher length of some 300 mm... which is pretty short.
This could be fixed by using a larger diameter chamber or a smaller diameter barrel.
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Urban Ninja
- Specialist 2
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Mon Jan 02, 2006 12:02 am
Ill probrably use a BBQ ignitor, but do you think that a piezo out of a lighter would work? Thanks.
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Technician
- Private 3
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Mon Jan 02, 2006 8:31 am
I agree with boilingleadbath as small barrels present their own problem when it comes to getting the right fuel/air mix and ignition. The smallest useful chamber fan is around 40mm so that's out, yet it would really help if you had one.
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spudshot
- Sergeant
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Mon Jan 02, 2006 12:24 pm
small chambers are a bitch to get right, i found that out the hard way with my pocket rocket, about 1 in 10 tries would work, i've got it down to a science now, i use butane from a mini torch