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Inline vs Over-Under

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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Inline vs Over-Under

Unread postAuthor: Hubb » Wed Jul 30, 2008 8:17 am

I'm currently designing another combustion which will have a chamber of 3" Sch40 chamber 18" long, over/under. My current launcher has a 3" Sch40 x 12" chamber, inline. Both sit at .7:1 ratio.

I'm aware that an inline gets better performance than an over/under design, but has anyone conducted tests or similar to determine by how much? How will my current designs compare to each other?

Also, while searching this in the Wiki, I came across the Vogt design. Would this work with a combustion?
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Unread postAuthor: starman » Wed Jul 30, 2008 9:10 am

If you mean this Vogt design, you never know until you try I suppose.

I can't see it being as effective or predictable as the pneumatic version...and your best highest pressure would be 80-100 psi with a 1x combustion setup. Also I have to wonder if the combustion blast wouldn't be too fast to allow the venturi effect to impart much momentum on the balls before the whole thing is over.
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Unread postAuthor: Hubb » Wed Jul 30, 2008 9:22 am

I have to wonder if the combustion blast wouldn't be too fast to allow the venturi effect to impart much momentum on the balls before the whole thing is over.


That's what I was thinking about. I don't plan on trying it, but I may on my next pneu project. it sounds like fun.
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Unread postAuthor: frankrede » Wed Jul 30, 2008 1:55 pm

I highly doubt it would work on a combustion.
IIRC
Cannons that use the VOGT pattern have oversized chambers for more air.

I prefer inline combustions:)









"The chamber volume should be at least 4 times that of the combined barrel/magazine volume."
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Last edited by frankrede on Wed Jul 30, 2008 2:20 pm, edited 1 time in total.
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Unread postAuthor: Hubb » Wed Jul 30, 2008 2:00 pm

I prefer inline combustions:)


I do, too. It's just that this next design, and its size, is going to be just too big to have fun with once constructed.
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Unread postAuthor: BigGrib » Fri Aug 01, 2008 12:52 am

It all depends on how compact you want your cannon. That's a question that only you can answer.
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Yea, that's definitely going to get you at least a tazer.

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