Actually, the mix that I'm referring to is the mix number in a hybrid. Not the fuel-air ratio. A 1x mix is at atmospheric pressure. A 10x is ten times the fuel and air of a 1x mix. Multiple points ignites multiple flame fronts causing the mix to burn faster. Using the stun gun ensures that you have...

So, using multiple ignition points can even make your launcher's shots more powerful and stun guns allow you to be 'less strict' with the fuel mix you are using? That's interesting.

I was just wondering why people use high voltage ignition (tasers) for their spud guns. Is it just so the launcher is more reliable (so there are less misfires)? Is it because hybrids need more ignition power? Also, does having ignition at two different points make the launcher more reliable? Thanks.

I think I have found a way to find the pressure after all. I found it before I read your post (but I read it anyway), thanks anyway for the link.

Yeah, I hadn't realised that and it's obvious there's a temperature change during combustion. I was reading your other reply and I wonder if you could use an example, since I'm not sure if I understand what you mean. Thanks.

I just found this: http://s87572736.onlinehome.us/Writeup.html and thought that it might be interesting to consider the force of atmospheric pressure so that: Wc - Wa = Ec (Wc = work done by combustion force, Wa = work done by the force of atmospheric pressure) Since W = F*x and F = p*S (p0*v0)/(v0+...

I would like to calculate the pressure created by the combustion inside a combustion cannon, therefore the pressure that starts pushing the projectile through the barrel. I thought that: W = p * dv (W for work, p for pressure and v for volume) And if we consider that: W = Ec (kinetic energy of the p...

Ok, I'll try that then.

Yes, I got a flame each time I opened the end cap and as I put more propane the flame got bigger so I thought it probably needed more air inside the chamber. As for the fan, even if I cut the corners it didn't fit in the old launcher, but I've seen it does fit in the new one. Just another question: ...

Finally I've solved the problem. I made a new launcher and realised I had been using too much propane for combustion to happen. It seems that with the propane meter more gas comes out than with the torch head. So I just used less propane (without fan in the end) and the launcher worked. Thanks for t...

If you mean cutting the corners of the fan that make it square shaped, I could try but it wouldn't fit anyway. My chamber is really small so I'll just make a new cannon like I said.

I found a CPU fan which I could use for the cannon, but it doesn't fit in the chamber. Since the chamber is so narrow I'll just build a new cannon and test the metering system there. I'll post the results when I get this done.

Thanks for the replies. I'll try to place a chamber fan (or the bouncy ball) and post the results. As for the structure of the cannon, I know how it looks but it actually works fine and I'm already planning on doing a proper PVC one (but I need this one to work with the meter first). I was also vent...

I recently made my first combustion spudgun. It's quite simple: It's fueled by a propane torch head (not direct injection) and the igniter is a simple igniter that creates a small flame. It worked fine. http://i50.tinypic.com/103d09c.jpg However, I decided to inject propane directly to the chamber, ...