[Ginger Power]

I currently have a limited budget and an air tank with only one port which is for a 1/2" NPT fitting. I'm aware that most people here reccomend going no less than 3/4" NPT as the smallest point from tank to barrel. So can I make a 1/2" NPT fitting work? What other aspects of the T-shirt cannon can I modify to increase shot distance? Obviously increasing the barrel length will help, but how long should it be? Is there a way to calculate how the barrel length will affect shot distance?

For reference, the T-shirt cannon will be mounted on a drivetrain with 4 pneumatic wheels, and will be designed to be used at high school football games. The air tank is a 10 gallon tank, and it will be filled with an off board compressor.