Add this to the con file (not the tweak file!)
All the other drivable vehicles have this, the rocket probably needs this too.
I bet I can get this rocket flyable before you. Mwuahaha I challenge you to a modding race.
Woot. I won! I modified the rotation settings on the engine and finally got the rocket to be flyable. Original settings made the rocket impossible to fly. (It would just spin out of control).
Video uploading now.
One tip though....Don't die. If the rocket dies from hitting something (not an issue if you left the hitpoints at the default 9999) then the game will CTD. I think either the rocket doesn't have a wreck mesh or might need wreck effects added to it.
Finished Code attached. Extract rar file and place con file and tweak file in same location as old files. (replace them with these that is). I remmed out remotecontrol component, replaced most of the physics wings with those from a plane, added a seat and camera, added physics type to con file, and altered the rotation/speed/acceleration vectors on the engine as well as remmed out the gear ratios code.
Keep in mind it's a roughly copy. You can fine tune the rest like the seat and camera position. I fixed the CTD at death issue by setting timeToStayAsWreck to zero and adding a few armor effects. Also note that in it's current state, if the rocket dies you fall of as a dead body.
Interesting as this does not occur on the other vehicles. It would be cool to have dead bodies fly out of jeeps and planes when they explode.