[ASD20]

I would not design the system around aiming for a specific distance, but rather just try to design a system that shoots as far as possible. It's cool to try to do the physics, but kinematics does not account for many real life inefficiencies, such as air resistance that are present especially when shooting something like a t-shirt.

In order to get a good shot, you will want to make sure you have as large a flow rate as possible in your solenoid. Some other important variables that I considered when designing a t-shirt cannon are air pressure, barrel length, and volume of air needed. I am sure other, more experienced people, may have slightly different lists. If designed well, you should easily be able to shoot 50 feet and if you need to lower the range, it is fairly easy to lower the air pressure.