Team 314 is using a "spear gun" tubing catapult and we find it effective for about 700-900 shots before we have to replace it which when done is cut to correct length then tested with scale to make sure of the same force. We have changed it 3 times through build season and our first district this weekend which was kettering. I dont know what all of you consider accurate or a "good" launcher but if you want to judge go to youtube and FIRSTinmichigan and you will find archived matches. Ill leave this one up to you guys to decide.
