Ok so i'll try and upload some more pictures. I just got back from our homecoming football game where we shot even more shirts. this time we lobbed them nearly straight up (sometimes it went clear over the crowd... oops). i believe we were using around 45 psi. and yes, only air is being used to launch the shirts. and to answer someone else's question, this was our tetra-stacking robot with the tip of the arm removed.
edit: here are some more pictures.
http://i13.photobucket.com/albums/a2...a/IMG_9166.jpg
http://i13.photobucket.com/albums/a2...aircannon2.jpg