| This strong turbine engine consumes liquid fuel and outputs angular acceleration. Also emits a pleasently high pitched whine.
— C7 Aerospace Division
This engine consumes intake air and liquid fuel to produce angular acceleration (rotation). When you put a set of propellers on it, you can produce thrust. The engine alone doesn't produce thrust. Setting up the engine is tricky, and doesn't have control via throttle by default. It is recommended to set throttle for propeller pitch instead of rotation or torque. Note that the engine requires intake air, so it only works on Kerbin and Laythe. One planets or moons that have a non-breathable atmosphere (Eve, Duna, Jool), electric motors such as the EM-32 Standard Rotor need to be used for propeller planes.