AC-80

Its mainly due to weight and the rocket fly though the thing it is connected to during flight. I think at a certain area the rocket engines just happen to glitch. But it isn't to do with when it is on the launch pad. Also with some designs the rocket tears itself apart.

I totally agree ilithyia. I just hope that eventually this will be fixed as the KW rocketry pack is beautiful and I hope I can get to use it properly eventually.