Hi, for a project at college i am building an ice hockey puck launcher for the development and training of ice hockey goaltenders. I am planning on using two wheels rotating in opposite directions to launch the puck. The pucks will be fed in by a pneumatic cylinder that is powered by a pressurized vessel. The wheels themselves will be driven by a starter motor from a car and six 12V batteries. I havent decided whether to use belt or gears to drive the wheels but i will get to that later in the project. Now, im basing my system somewhat on the tennis ball launchers you see at tennis courts. They use two hard spinning wheels that compress the tennis ball to create more friction between the wheels and the ball. With my design I won't be able to do this because the hockey puck is made of a very hard rubber compound. This means i am using pneumatic tyres so that rather than the puck compress, the tyres will. However, i need to include some calculations in my project but im not sure what calculations there are for this sort of thing. Obviously i can work out things like the torque and rpm of the wheels but really i need some sort of calculations that translate this torque/rpm etc into the speed that the puck will be fired at. Anyone got an ideas? Any help would be much appreciated. Thanks.