Q.A. Inc has come up with a revolutionary new design for engines. The engines move when you pitch, yaw and on the double engines, roll.
The engine with the red front is meant for single engine crafts only. First, detach it by detaching it from the red fuselage price that's connected to the engine. Then save as sub-assembly.
The engine with the blue front is meant for twin engine crafts only. It has roll, pitch and yaw built in. WARNING!!!! Save each engine as a separate sub-assembly!!! Also, do not mirror the engines! You will need to place both by hand!!! Detach both engines from the blue fuselage piece and save as a sub-assembly.
Please give credit if used.