Design Optimization of Rotor Systems for Tilt-Rotor Aircraft That Fold for Shipboard Compatibility

Preliminary design studies have identified the best design concepts for 4-bladed prop-rotors that must fold for shipboard compatibility. All practical combinations of folding method and hub configuration were evaluated for operational suitability, maintainability, reliability, cost, and developmental risk. Results show that the scissorsfolding hingeless rotor is best if the aircraft configuration can accept a prop-rotor folding length of the prop-rotor diameter. For an aircraft configuration that requires the prop-rotor to fold to a length of approximately the rotor radius, a flexure and elastomeric articulated hub is the best choice.