🌬️ Rotor Spin-Up, Spin-Down and Wind Torque: Turbine Shaft Dynamics Case-Study Lab

A flywheel bench, a spin-down test and a fixed tip-speed-ratio turbine from the original scenarios in one rotor-shaft model, extended with wind torque from a power-coefficient curve, a generator load and a free rotor, checked against closed forms and a steady-state root-finder.