The present invention relates to a rotor having a hingeless and bearingless blade connection for a rotary wing aircraft. The rotor or wing blades are connected to a rotor head by a respective blade neck section which is yielding or flexible relative to blade angle adjustment movements as well as relative to flapping and lead-lag movements. The connection points between the rotor head and the flexible blade neck sections are stiff. The blade angle adjustment is accomplished or controlled for each rotor blade by a control rod extending from the center of the rotor head so as to bridge the respective flexible blade neck section. The control rod is stiff against torsion loads.
A rotor as just described is relatively simple in its construction and its structural weight is correspondingly small since separate mechanical blade bearings and blade hinges have been obviated. Additionally, such rotor type is less prone to wear and tear as compared to other conventional rotors. However, due to the absence of blade angle bearings the individual torsion yielding or flexible blade neck section requires a large structural length for strength reasons. As a result, it is unavoidable that the flexible blade neck section is subject to substantial excursions in response to the blade flapping movements and in response to the blade lead-lag movements. Therefore, it is necessary to decouple the torsion stiff control rod for the blade angle adjustment from these excursions of the blade neck section to the extent that such excursions do not impair the operability of the control rod. Heretofore it was customary to accomplish said decoupling by means of a special cardanic or universal joint which forms a hinge type bearing for the control rod. This hinge type bearing is yielding against bending loads, but stiff against torsion loads. The hinge type bearing is arranged at both ends of the control rod at the blade proper and at the rotor head which does increase the risk of damage to the rotor or to the means for the blade angle control or adjustment.
German Patent Publication (DE-OS) No. 2,658,828 discloses a rotor head which simultaneously performs a housing function for the means for controlling the blade angle adjustment.
German Patent Publication (DE-AS) No. 2,806,119 discloses a type of rotor blade or wing blade suitable for the present purposes.
USPTO Backgrounds
USPTO Backgrounds