I just re-did the numbers - - no rocket science. Propane: 2 C_3H_8 + 8 O_2 - - > 4 H_2O + 6 CO_2 == 2 mols of propane to 8 mols of oxygen == 88 grams of propane to 256 grams of oxygen == 48 liters of propane to 853 liters of air Propane is 5.3 % of the mixture Butane: 2 C_4H_10 + 13 O_2 - - > 10 H_2...

The flame is not supposed to pass through the valve, but OK it may backfire by the time the air tank is about to run empty.

I was thinking about a piston valve (coaxial or supah).

Soren

I'm only worried that it will be hard to get the gas to ever burn. Igniting gas at x00 MPH and @y bar pressure could be hard. Maybe one of those shelter-things around the burner, as in a real jet engine, would do good. But this has to be tried out. It if fails, it can always just serve as a regular ...

Hi, Having finished my supersonic combustion gun, it's time for me o move on - with something that I don't know if it will work, like last time 8) I thought about this: A hybrid gun that works in the opposite order of the usual: Release first, then ignition. Basically a modified pneumatic gun, witho...

It's actually not so hard to calculate the stoichiometic ratio -- you need to, basically, find out how many molecules of the gas react with hoe many of oxygen. Then, you multiply both with the molar mass of the gas vs. the oxygen, and you have a gram:gram ratio. Then, you just divide both by the res...

A good igniter and careful adjustment. One day, in humid weather, it would not work unless I shorted one of the spark gaps, though.

Søren

Flinchy: A BBQ sparker. I tried to get an auto spark coil to work, but it was too weak. And my friend, who knew about the project, tossed out his old 32" CRT TV the same weekend -- not even bothering to salvage the flyback!!! Søren PS Yes this is not kit-gun land. Most materials, apart from the barr...

noname, I guess we still need to say that the pressure in the chamber will -- hopefully -- rise to something significantly higher then when the bursk disk burst (because of continued combustion). If not, one might as well save the propane and add a little more air instead, right? I wonder about one ...

EEeeeeehh .. oxygen enhancement makes a gun hybrid?

Isn't a hybrid gun a combination of a pressurised gun and a combustion gun? -- the pressurization being a different way to stuff more oxygen into the chamber? I don't pressurize; I increase oxygen concentration instead.

Søren

I think my neighbors would wear out before that pipe :wink: I guess I will try with 60% oxy and a spud, while standing pretty far behind the breech (the safest place near that gun :P ) If it blows up, well, there is only one sound barrier and it has broken it. I think (don't have anything empirical ...

I used to have a gun larger than that, but I used a lot less fuel. Try, instead of 1, 2 or 3 seconds, 1, 2 or 3 pretty light taps on the propane can (do you inject into a small hole you have drilled? If not, you might want to drill one. 1.5 millimeters or around there.) If it ignites but performs lo...

Nice enough gun; I like the steel body but not the duct tape. If you use a spark plug cable or a high voltage cable from an old CRT TV, that will insulate well, too. Try adding LESS fuel. And butane would probably be perfectly safe with a steel gun, + more powerful, cleaner and cheaper than deodoran...

Hi, If any of you have wondered if it is possible to shoot > Mach 1 with a butane gun, I found the answer a few months ago: It is. The gun is made of unrated PVC pipe (somehow I'm still alive, but rated pipe is just too hard to get by in Denmark -- nobody does DIY plastic plumbing). The chamber is 1...