Better flights with a twist

When designing a rotary aircraft such as a helicopter or tilt-wing, engineers must strike a balance between the blade angle that works best for forward flight and the angle that works best for vertical flight.

Through a project called the reconfigurable rotor blade (RRB), the Office of Naval Research is supporting development of a device that twists the blades in-air to optimize the angle for each mode of flight and thereby increase aircraft fuel efficiency, range, and payload.

ONR and the Naval Air Systems Command are jointly developing the RRB, with Boeing acting as the prime contractor. "At the heart of the RRB is a solid-state, electronic torsional actuator that changes the 'spanwise' twist of a blade, allowing the rotors to operate at maximum efficiency during takeoffs and landings, and while cruising," said ONR program officer Lawrence Ash.

The small package—about 18 pounds—is compatible with the existing blade and hub structures on many Department of Defense helicopters and the tiltrotor V-22 Osprey, for easy retrofit.