Maybe one of you savvy people can show me how this is calculated?
F = p*L^2*ft(e,L/R,a)
F is pulling force of the pleated muscle
p is pressure
L is muscle extended length
e is extension
a is a number that depends on material elasticity and in ideal circumstances can be set to zero
You can find it in the first link in the above post (and in some of the other links).
I don't know how to calculate what's inside the parenthesis, and also what units to use.