why can't I get a better result when firing?

[wdotten]

I just made a standard spud gun for the first time but I can't seem to get the right fuel to air mix, it seems to be very unreliable, I use propane instead of hairspray but it still is shotty?? Anyone know what I can do to get it more consistent?

[saefroch]

A neophyte! Welcome!

You're looking for the section called "Combustion Cannon Discussion," in particular a sticky called How to Build a Propane Meter.

To actually answer your question:
No, using propane will be no more reproducible than other propellants if you're trying to gauge the mix by feel. You have to deal with variations in your timing and how far you're opening the valve, both of which will carry over to propane.

[jackssmirkingrevenge]

[youtube][/youtube]

[iknowmy3tables]

very basic combustion spudguns are often called spray and prays, if I'm correct this is more about reliable triggering rather than power right? here are some steps that you may want to improve your combustion cannon

1)first experiment, spray, vent, shoot try try different spraying techniques, virgin sacrifices, different fuels adjusting the spark gap, etc
2)upgrade your chamber to use a fuel mixing fan with a brushless motor
3)upgrade your ignition, try a camera flash circuit, a cheap stungun
4)finally make an fuel meter, it's usually considered a project for advance builders but when paired with that last two things you'll have completed an advance spudgun

[jsefcik]

personally, a fan will be the best improvment,i still have a spray and pray i put in a fan and best thing i ever did, carb cleaner !!!