SpudFiles

Instead of making a piston the way Fnord did with his hybrid, would it be effective to install a strong spring inside a swing check valve so it contains the pressure just enough before it ignites? The advantage to this idea (if it works) is that it is inline (less turbulence) and provides for a faster opening time and greater flow. My worry is that despite having a strong spring behind the swing, the air against the sealing face will still leak through because check valves are made to do that. Here is a diagram showing where the spring would be placed:

if the spring strong enough it be a good burst disk
advantages ( if i spelt that right) dont have to put a new disk in every time u get ready to fire/load it

I think it would cut down on flow though.

unfortunatly, it probably wont work. For a job like that you need something that will lock in place and then snap open with a certain force.

I cant really think of anything off the top of my head...

I might be a bit worried about the swingy thing hitting too hard inside the valve. Other than that the idea sounds pretty good...How do you plan on attaching the spring to the flap?

thedeathofall: I think you are right because if the valve can budge it will let out air.

noob of noobs: I am just toying with the theory right now but I am going to check out one of these check valves an see if the spring can be conveniently placed.

Depending on the pressures used, you might have a difficult time finding a spring strong enough to hold back the flap.

Whats the surface area hat your trying to push back?
That plays a role as well.

I had something similar cooked up a while ago, but abandoned it.

Replace the heavy spring merely with a light one to reseal the swing after opening, and attach the head of a ball-detent type torque wrench to the shaft the swing is attached to (assuming the swing is fixed to the shaft). That way, you can set the torque on the wrench to a high enough setting to hold back the pre-ignition pressure, but the clutch mechanism will allow the swing to open on ignition.

You want this thing to "pop" open instead of leaking. The simplest way to do such thing is to make it have extra surface area as soon as it starts opening. Like a popoff. This is also how most piston hybrids work.
It will be very hard to make this valve pop though...