Client hanging after launching rockets out of flowing water

When rockets are launched into flowing water, their flightpath describes an bow until 90° or more, then suddenly after several launches in short periode, the client hangs up, the server stays normal!
It does not happen when rockets are normally started or blocked by anything, just flowing water produces the problem.
And flighttime must be 3, so the rockets could fly sideways!

i suggest it's a problem with the physics when the rockets start flying downwards