you can create system that detects when rocket detached from launcher and starts thruster. just put 2 nor gates in rocket and 1 and gate in launcher, then connect and gate to 1 nor gate at rocket and connect this nor gate to another nor gate than connect second nor gate to thruster. How it works - when nor gate has no connections it gives 0 signal but if if has connection to inactive and gate it gives 1 and this output reverses by second nor gate so while rocket welded to launcher and gate from launcher connected to rocjet nor and it gives 1 and reverts it to 0 so thruster off but if you break cardboard piece on what rocket welded to launcher connection to and gate breaks and nor gate outputs 0 and reverses it to 1 so thruster on and flying rocket, so just weld rocket on cardboard with this system and enjoy rocket launcher that dont needs you to break blocks manualy /-------------------------\ /-------\ /-------------\ | | | | | | and gate nor gate norgate | launcher rocket thruster