I had this same problem. Most of my hand launches were marginal at best and it just didn't seem to work well, so I built a catapult from Warbirds ltd. It worked well but wasn't very powerful, and some of the launches just barely missed the ground, but at least they were level. I modified the catapult so it ran on ball barrings and added 2 pegs that hold back the airplane when the launcher is pulled back so I can throttle up to full power before releasing the launcher. Ever since I made those modifications I haven't had a problem launching. The design is fairly straight forward. I'll have to dig through my pictures to see if I can find good shot of the catapult if your interested in it.