SpudFiles

I wanted to convert one of my combustion guns to a hybrid, but didn't want to have the chamber under the barrel; I wanted to keep the chamber behind the barrel in a straight line. I came up with these pictures, but my only question is if you can actually get a 4 way T needed for the second piston. I assumed they make them, but I'm not entirely sure. If you can get one, I think this should work fairly well.

Yeah they do make four way thingys (don't know what they're called) but i don't get the idea of your piston thing.

Well when they chamber is pressurized, the spring holds the first piston up, but when it fires, the spring isn't strong enough to hold it up, so it gets pushed down. The 2 pistons are connected, so when the first one gets pushed down, it pulls the second one down as well, and opens up the barrel.

But when it fire its just going to rip the piston off .
EDIT: or your not going to find a strong enough spring and it will be pushed down when u presurize.

And I doubt that your cannon is made out of high pressure rated parts. If it is just buy a union.and cut off the barrel about 2inchs from the chamber and glue it on.

His idea is basically a reusable burst disk. This idea would'nt work, the air/fuel would just go around the piston, this problem has been overlooked in many people's designs.

...yes, it's very difficult to make seals in that manner.
I wonder if one could modify a gate valve...

how about modifying a home-made slide valve? it could work....

Whats a home-made slide valve???And anyway why mess with something that works fine?

As BLB said, good luck getting that bastard to seal. I do have an idea to make it seal though, I'll post my diagram up when I get a chance.

here my change to the disighn that may i think acualy work but hey never know till u try.
things still to think about with it....
keep the pistons lubricated
distance of the rods holding the pistons and how long each should be to just clear each from the barrel when forced down