Dual rotor, rotary wing aircraft

A rotary wing aircraft, comprising:

• an airframe;
• an extending tail;
• a counter-rotating, coaxial main rotor assembly including an upper rotor assembly and a lower rotor assembly, wherein at least one of the upper rotor assembly and the lower rotor assembly includes a main rotor blade;
• and
• a translational thrust system including a propeller positioned at the extending tail, the translational thrust system configured to provide translational thrust to the airframe, wherein the main rotor blade includes a root region, an inboard region, a main region, and a tip region and at least one of chord, twist, sweep, airfoil shape, and thickness/chord of the main rotor blade assembly has been optimized to achieve balanced high speed forward flight and hover relative to both efficiency and high thrust capability.