neeewwww wrote:@spudmanb3 - I were planning to use a 1" or 3/4" Ballvalve actuated by spring... So, going from a 3/4" or 1" BV to a 1/2" QEV wouldn´t be THAT perfomance gain or I´m wrong?
Performance gain or loss comparing a QEV and ball valve boils down to how fast can you open the valve? When open the ball valve beats the socks off a QEV because of a larger orifice and no bends in the flow.
In a ball valve the loss is due to the short distance from the breech to the muzzle. The projectile has left long before the valve is open very far, so most of the shot is done with a mostly closed valve. The advantages of a QEV start to shrink as you move to longer barrels with very large chambers. A small high pressure launcher has poor results compared to a QEV with the slow ball valve.
Even those with large cannons and long barrels have to find ways to get a ball valve open quickly to get reasonable performance.
This video is from one of our competitors in the Engineering Challenge. This cannon did not place. We beat them in a landslide with a faster valve.