This example shows a fixed helicopter transmission testbed. The gasoline engine provides power that is sent to the main and tail rotors through planetary gearsets. The main rotor shaft is considered rigid, and flexibility is modeled in the longer, thinner tail rotor shaft. Blade pitch angle is set directly via a physical signal. Swash plate dynamics can be added using the appropriate blocks in Simscape™ Fluids™. The engine stalls after six seconds, but lift is maintained for some time through the unidirectional clutch. This scheme also allows autorotation of the main rotor in a descending helicopter.
The plots below show the torque supplied by the engine and the torque applied to the rotor shafts. The engine is permitted to stall after 6 seconds. Induced and profile drag on the spinning rotors act to slow them down.