SpudFiles

I usually opt for pneumatic cannons but I figured I would give my had at a combustion.

Barrel - 1"SCH40 pvc, 30" long.
Chamber - 1.5" SCH40 pvc, 10" long (C:B ratio at .8:1).
Ignition - piezoelectric igniter, wired to a spark gap in the chamber (to constantly create sparks without fail).
Fuel - propane and propane accessories

Other details include an EZ-bar attached to the end cap to aid in removal and a fuel / air mixing device (similar to a Chambah Chain). Reasons for the mixing device is because I couldn't seem to get a fan to work with such a small chamber.

Shots average about 100 yards with a 16P nail wadded with duct tape.

Oh yeah, it looked kind of ghetto earlier so I took the liberty of painting it so you guys wouldn't tell me to.

Very nice, clean little combustion.

Trying to find a fan that will fit would be my only real suggestion.

Can you use that fuel injection system as a meter, or are you just cracking the valve and counting x seconds? How reliable is it?

Peace,
Pete Zaria.

Very clean look dude.

What exactly is your setup you use to mix the fuel? I'm planning on a external fan for my next combustion. Both combustions I have built have had problems with the fan (pear & persimmon juice).

The propane injection has a quick connect. I plug in the tank, and crack the valve to the torch then turn it back off. I remove the tank then open the ball valve. Then its shake and bake.

As far as reliability, once I figured out the technique of injecting the propane, it fires each time. The ammo (last tested with a glow stick wrapped in tape, due to darkness and lack of spuds) comes out the muzzle with a crack like a .22. I shot it straight up and got me a "1/4 mile."

I also forgot to mention that the cannon is muzzle loaded. The male adapter is for removing the barrel to aid in cleaning (which needs to be done) and exhausting.

@Dornep: The hose clamp used to secure the piezo to the chamber was too long so I clipped it down some. The little piece of hose clamp left was then tied to the interior of the chamber.

UPDATE:

After shooting this thing several times, I have noticed several problems. Over the past few days, I've opted to fix these.

The first, and most noticable, was the lack of a chamber fan. I upgraded the chamber from 1.5" to 2" SCH 40, then placed a small computer fan in the female adapter (the new chamber looks exactly like the old one).

Next, I added a bolt to the end cap, the epoxied it in place. This allows me to use a wrench, if necessary, to remove the end cap. The nail was just not long enough and began cutting my hand.

Pics will be posted as soon as I test fire it and get kinks worked out.