There are two ways: you can use a Wraith or Scorpion Tank by going into forge mode and putting them inside it and lifting etc.
Or the other way is put a lot fusion coils in and forget the respawn time, all you have to do is go to one fusion coil go into it's summary (press X) and change the run-time minimum to the same as the run-time maximum and there you go the bomb will never stop which will make the elephant fly!
Note: You can do this bomb thing anywhere else on any map it will continue blowing up and killing any stupid idiot who tries to run through it!