Analysis of advanced ducted rotors and blade structural design

• An aeroelastic model for ducted rotor analysis has been formulated, the model is based on the duct lift and pitching moments estimation and can be further modified by future test data and CFD simulation • The ducted rotor hub vibration is studied in forward flight. The results indicate that the fully ducted rotor will experience low vibration due to the shielding of the duct • Partial open ducted rotors can experience increased vibratory hub loads due to azimuthal variations in the duct-induced rotor inflow, blade tip-loss effect and the blade sectional in-plane air velocity changes • The stiff rotor without cyclic pitch controls can cause asymmetric flap responses, leading to increased blade bending moment (50%) and static hub moments. Further study is required to determine affect on bladed design and vehicle trim • The composite blade design study is conducted, the design is based on the max. allowable strain criteria and the required blade stiffness with satisfactory dynamics • The flap-torsion coupling of the composite blade is explored for its effect on the stiff rotor without cyclic pitch controls. The results indicate that it can reduce the peak root flap bending moments by 10% or even more with reduced torsion stiffness.