Sorry for delay, but no, however will google them after this reply, thanks for lead. My problem is this, I think I have a viable design for imparting a fair amount of velocity to the ball. It uses a dense coil of catapult elastic which is stretched using a geared crank. releasing the coil propels the ball via a bellows type arrangement which in effect is a large caliber pea-shooter. I want to estimate the range of the design as it stands to see if it will reach the minimum 50m range. To do this I guess I need to find muzzle velocity and then find the amount of energy needed to accelerate the ball to that velocity. Then I need to figure out the amount of energy that can be stored by the elastic. I am hoping the quantity of elastic in the design is sufficient to achieve the range. Any further hints welcome.