Main rotor for a helicopter
Rotor blade, especially for a rotary wing aircraft
Hubless, hingeless and bearingless helicopter rotor system
Auxiliary helicopter rotor
Composite flexbeam for a bearingless helicopter rotor Patent #: 5096380
ApplicationNo. 903061 filed on 06/22/1992
US Classes:416/134A, Aircraft rotors416/138, With manual control means416/141Plural articulation
ExaminersPrimary: Look, Edward K.
Assistant: Sgantzos, Mark
Attorney, Agent or Firm
International ClassB64C 027/33
AbstractA rotor blade subassembly for a rotor assembly having ducted, coaxial counter-rotating rotors includes a flexbeam, an integrated torque tube/spar member, and an aerodynamic fairing or rotor blade. The flexbeam is a laminated composite structure that reacts centrifugal loads and a majority of the bending loads of the rotor assembly. The flexbeam has a spanwise predetermined linear twist so that the pretwisted flexbeam is unstrained during specified forward flight conditions. The integrated torque tube/spar member is formed as a continuous, filament wound tubular composite structure having high torsional and bending stiffness that provides a continuous torsional load path and facilitates load coupling between the rotor blade and the pretwisted flexbeam. The spar segment of the functions as the primary structural member of the rotor blade subassembly and, is operative to react all bending, torsional, shear, and centrifugal dynamic loads of the rotor assembly. The torque tube segment reacts all torsional loads and some of the bending loads of the rotor assembly. The rotor blade is fabricated from a high modulus composite material and has a high aerodynamic taper such that the tapered rotor blade has a low outboard mass, a high inboard stiffness, and a high chordwise frequency. The high chordwise frequency allows the rotor assembly to be operated over a weaker modal response zone. The tapered rotor blade includes a triangularly shaped trailing edge segment that is responsive to the aerodynamic pressures encountered during operation of the shrouded counter-rotating rotors.