[euhlmann]

We use a catapult-like pneumatic arm instead of a shooter wheel, but we have found that as other people have stated on this thread, the values we set to make shots look really arbitrary. They're most likely a combination of multiple physical effects and very hard to predict.
We used linear interpolation between values in a lookup table we got from test data. It's been very successful so far, and I suggest you do something similar instead of trying to simulate the physics of the shot. Retaking values for the table took us about 15 minutes on the practice field before our competition last weekend, so it shouldn't be too hard after you've done it a few times.