F=k * (Lfree - Ldef)
- k is spring constant
Lfree is the uncompressed length of the spring
Ldef is the compressed length of the spring
The force on a piston is found from
F = P * A
- F is force
P is pressure
A is area
So combining these two we should be able to work out suitable springs for the whole series of JSR and SPG spring related autos. Only thing is that's as far as my physics gets me, I can't work it out on practical level.
Lets say I have a blow-forwards design. I need to have 1/2 inch of piston travel, and I want that to happen at 110psi. What spring should I pick?
And next problem, I know that coil springs aren't constant rate, but Ideally I want the force on the spring when uncompressed to be sufficient to shut a valve. and not have the whole thing hang half open in a JSR like way.
I'm thinking that it might be better to pre-load a spring, but again my physics lets me down.