I am confused

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.
Hashbrowwns 4flip
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Sun Jul 29, 2012 5:08 pm

So I built my propane injection launcher and all the test fires went perfect. Put spuds through 3/8 inch plywood at 50 feet and fired consistently. I know my mix is a little rich because I used a 4 inch nipple because I couldn't find a 3 and 1/2 inch. Took it apart to paint it. Made a golf ball barrel. Put it back together . Took it to the mountains and it isn't getting enough air so it is now inconsistent. Haven't tried it at home again yet. A few thousand feet shouldn't change atmospheric pressure enough to throw me that far off should it? Could weak batteries cause the fan to not blow hard enough?
evanmcorleytv
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Sun Jul 29, 2012 9:18 pm

Hashbrowwns 4flip wrote:So I built my propane injection launcher and all the test fires went perfect. Put spuds through 3/8 inch plywood at 50 feet and fired consistently. I know my mix is a little rich because I used a 4 inch nipple because I couldn't find a 3 and 1/2 inch. Took it apart to paint it. Made a golf ball barrel. Put it back together . Took it to the mountains and it isn't getting enough air so it is now inconsistent. Haven't tried it at home again yet. A few thousand feet shouldn't change atmospheric pressure enough to throw me that far off should it? Could weak batteries cause the fan to not blow hard enough?
Yes, a change in atmospheric preddure can affect copmbustion cannons. Go to Spudtool online.
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Hubb
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Mon Jul 30, 2012 3:40 am

If you were already rich with your mix, then taking oxygen away is only going to make it worse. As suggested, check the calculations and go from there.

You also said you've taken it apart. Check it over a couple of times to make sure everything went back the way it was before.

Good luck.
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mark.f
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Wed Aug 01, 2012 9:37 pm

I notice you're getting the desired amount of fuel by adjusting the meter volume rather than pressure. It would be much more accurate to use a larger meter pipe and adjust the pressure using a regulator.
Hashbrowwns 4flip
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Thu Aug 02, 2012 8:59 am

Guess I will buy a regulator. Thanks guys
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