Rotor Preliminary Design Trade-Offs for the Advanced Scout Helicopter

The sizing of the main-rotor design parameters in the recent ASH (Advanced Scout Helicopter) preliminary design study is documented. The parameters considered are disc loading, tip speed, number of blades, chord, and blade inertia. Four ASH configurations are considered: (1) single fixedsize engine; (2) single rubber engine; (3) twin rubber engines sized by twin-engine vertical rate of climb; and (4) twin rubber engines sized by single-engine hover in ground effect. A constrained optimization is conducted to find the best design for each of the four configurations. This optimization is dominated by various constraints, including: a maximum disc loading, a maximum tip speed, a maximum blade loading, a minimum blade chord, and a minimum autorotation performance.