Rotor blade, especially for a rotary wing aircraft

Claim 1

in a rotor blade for connection to a rotor hub, especially for a rotary wing aircraft, having a radially outer blade wing section, a radially inner blade root section for connection to said rotor hub, and a blade neck section interconnecting said blade wing section and said blade root section in a torsionally yielding manner, the improvement comprising a torsion stiff blade angle control sleeve bridging said blade neck section without contacting said blade neck section for transmitting blade angle adjustment torque moments to said blade wing section, said torsion stiff sleeve having a circumferentially closed radially outer end, first means rigidly connecting said circumferentially closed radially outer end of said torsion stiff sleeve to said blade wing section, said torsion stiff sleeve further having a circumferentially closed radially inner end connectable to blade angle adjustment means for adjusting a blade angle through said torsion stiff sleeve, second means for flexibly connecting said circumferentially closed radially inner end of said torsion stiff sleeve to said blade root section, said torsion stiff sleeve further comprising a leading edge, a trailing edge and a longitudinal inspection gap in said trailing edge, said longitudinal inspection gap extending intermediate said circumferentially closed radially inner and outer ends of said torsion stiff sleeve for visually inspecting said torsionally yielding blade neck section through said inspection gap, said torsion stiff sleeve having a reinforced upper longitudinal edge and a reinforced lower longitudinal edge along said inspection gap for compensating any loss in torsion stiffness of said torsion stiff sleeve due to said inspection gap, whereby said torsion stiff sleeve permits a proper blade angle adjustment and also a visual inspection of said blade neck section.