Thanks for all the comments, and I happen to be an engineer, so maybe that's why I don't ask many questions? By the way, the launchers were used last night at Metlife (Giants) stadium in NJ. Fired from the sideline, the "flaming arrows" landed on the far line of hashmarks for about 30 yards distance...

I built these 2 air cannons as props for the high school marching band that 2 of my kids play in. The concept of the show this year is medieval knights, castles, etc. So the idea of flaming arrows shot from the "castle" came about. The idea is to shoot 2 arrows from each side of the field at the sta...