Abstract: A rotor blade includes a spar with forward end, an aft end, and a substantially oval cross-section. The cross-section includes an upper portion tapering from a first thickness to a smaller, second thickness beginning between about 55% and about 65% of the distance to the aft end from the forward end and ending between about 65% and about 75% of the distance to the aft end measured from the forward end, and a lower portion tapering from a third thickness to a smaller, fourth thickness beginning between about 55% and about 65% of the distance to the aft end from the forward end and ending between about 65% and about 75% of the distance to the aft end measured from the forward end. The rotor blade further includes an upper blade skin, a lower blade skin, and a leading edge sheath.

Abstract: A rotor blade for a rotary wing aircraft includes a leading edge and a trailing edge defining a chordwise direction. The leading edge defines a forward end of the rotor blade and the trailing edge defines an aft end of the rotor blade. The rotor blade has a center of gravity and an aerodynamic center along the chordwise direction. The center of gravity is aft of the aerodynamic center.

Abstract: A rotor blade for a rotary wing aircraft includes a leading edge and a trailing edge defining a chordwise direction. The leading edge defines a forward end of the rotor blade and the trailing edge defines an aft end of the rotor blade. The rotor blade has a center of gravity and an aerodynamic center along the chordwise direction. The center of gravity is aft of the aerodynamic center.

Abstract: A rotor blade retention assembly is configured to connect a rotor blade to a central hub comprising a hub arm coupled to and extending radially outward from a hub bowl. The hub arm includes a hub arm lug. The rotor blade retention assembly includes a tension-torsion strap with an inboard end and an outboard end, the inboard end including an inboard pin hole and the outboard end including an outboard pin hole. The rotor blade retention assembly further includes an inboard blade pin and an outboard blade pin. The inboard blade pin is configured to extend through the hub arm lug and the inboard pin hole and to couple the inboard end of the tension-torsion strap to the hub arm. The outboard blade pin is configured to extend through a blade lug of a rotor blade and the outboard pin hole and to couple the outboard end of the tension-torsion strap to the rotor blade.