what about something like this? when the part of the chamber on the left side of the piston ignites it pushes the piston to the right venting that side and vice versa.

My first post says it all.
http://www.spudfiles.com/forums/help-wi ... t5396.html

Ok thanks. so if I heat the alcohol I also have to add more air to keep the correct mix? I think this will be too complicated for my current design since the alcohol would have to stay heated for a long time before the shot. If i heat it and it cools off, the alcohol that evaporated will just conden...

Will liquid isopropyl alcohol evaporate to a combustible mix if poured into a closed container? also if more air was pumped in to the chamber to try to create a higher atmospheric mix, wouldn't less alcohol evaporate? does anyone know what the highest mix you can do before the alcohol can't combust?

I don't think i can return it, I've had it for over a year. anyways I'm getting some that actually have at least every 5 psi increment marked. I'm getting a 0-30psi and 0-60psi which are in 1 psi increments for propane fueling and another 0-160 for air. do you think I need a gauge with more the 1 ps...

Me and Drex have been working on a hybrid and we couldn't get the fueling right. I think i found out why. I found the volume of the meter and the volume of the chamber + meter by filling it with water. the chamber + the meter was 759mL and the meter was 74mL. I then pressurized the meter to 100 psi ...

Is the black square the regulator? I think it will work as long as the pilot side pressurizes first except for the ammo loading part. I think the clip needs to be blocked when the piston is back, not when it is forward.

I've made hybrids before but I forgot if you count the meter as part of the chamber when you find the chamber volume since the gas in the meter will expand to the chamber and stay in the meter? most formulas that I have seen to find the correct amount of propane to use don't add the volume of the me...

Is this it?
http://www.spudfiles.com/forums/high-pr ... 18170.html

I'm would guess somewhere between $150 and 200. I'll guess $178 to try to win the 1000 internets.

The winner gets 1000 internets!

By the way what is an internet?

Make sure your battery is full!
If the phone starts beeping because of a low-battery the gun will blast away.

the phone i used died a few times while i was using it. It had a separate speaker that beeped for a low battery. That is a good catch though for other phones.

The nail was about 3/8" diameter. I got it at lowes. I used a sabot made out of aluminum foil and it worked fine(except for one shot where the foil went around the nail and the foil went through one sheet of plywood. )

The barrel was 1" diameter 5' long.
estimated 2000ft/Lbs and 400fps with a 19oz 10" long steel nail.

the blast chamber is made out of cinder blocks. it covered the back and both sides of the gun so that all of the shrapnel would shoot forwards into the trees.

We probably should have made it a little bigger but none of the shrapnel flew backwards so it was good enough.

I am guessing that one of the other 8x shots cracked the inside pipe but the outside pipe still held, then the last shot was mostly acting only on the 2" pipe. There was a lot of shrapnel but it all went straight forward into the trees. The barrier did its job. The only other damage was to my electr...