I was looking at some old grenade threads, and I saw Tsukiten's design, and I figured how to make it work. I would change 3 things:
1. Place a spring behind the piston, in between that and the schrader valve.
2. Put a check valve in the piston itself, making air move from the right side to the left, but not the other way, so it can be a perfect sealing piston when it vents.
3. Change the pin to a needle valve composed of a screw with teflon tape with a sharpened tip that plugs a hole in the other side, so when you unscrew it, it slowly vents air out of that hole.
The reason this would work:
When the grenade is filled, air would flow into the vent chamber, and through the check valve into the firing chamber. The needle valve would then slowly vent the right chamber, but because of the spring, it would stay closed for longer, even though the air pressures are now different. When the air would finally overcome the spring, it would trigger, blasting air out the back.
The link to Tsukiten's old grenade: http://www.spudfiles.com/forums/re-usab ... 15877.html
Improved Tsukiten's Grenade
I think with a needle valve for the vent even with a spring the valve will open relatively slowly. You need some changes in surface area so the forces will increase suddenly after a certain point.
Patience is a virtue, get it if you can, seldom in a women, never in a man.
I made a fairly successful airsoft grenade which I never used much. I'll try to find the link...<a href="http://www.spudfiles.com/forums/nonames ... l">Here</a>
Somewhat related I suppose.
Somewhat related I suppose.