chamber fan question

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
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Lentamentalisk
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Mon Oct 08, 2007 12:24 pm

I have heard that adding a chamber fan will increase performance by 30%, is that true?
also do you keep it running the entire time, or shut it off right before you fire?
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jimmy101
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Mon Oct 08, 2007 1:09 pm

A chamber fan will boost the performance of a combustion gun. I don't believe anyone has ever posted on exactly how much it helps.

"Boosting performance" really has two parts;
1. A fan makes the gun much more consistent from shot to shot.
2. It probably boost the performance regardless of the shot to shot variablity.

A chamber fan does at least three things:
1. Mixes the fuel before the shot.
2. Add turbulance to the the flame front, making it propagate faster, during the shot.
3. Helps ventilate the chamber after the shot.

So, the fan helps all three phases of shooting a combustion spudgun; loading, firing and venting.

If your batteries can handle it, leave the fan on all the time during a firing session.
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Lentamentalisk
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Mon Oct 08, 2007 1:15 pm

great! thanks for the clarification

...and make this post long enough...
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mtronic
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Mon Oct 08, 2007 5:06 pm

I just used mine to mix and vent, mine didnt want to fire for some reason while the fan was running :( I think my spark gaps were too close to the fan. If you had two spark gaps then maybe this would help?

But yes the power increase was very pleasing :D If your running a 4" chamber a 4" 12v fan fits snugly with a bit of tape at the corners, that way you dont need to screw it into place and only need one hole for the wires.
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