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Month in the Patent Office

Aircraft Engineering and Aerospace Technology

ISSN: 0002-2667

Publication date: 1 December 1950


In a rotary wing aircraft having two or more rotor blades either rigidly mounted or mounted on conventional flapping hinges and/or drag hinges, each blade is provided with one or more auxiliary masses so mounted on pivots attached to the blade as to constitute one or more small vibratory systems tuned to twice the frequency of the rotor. As shown, the blades j of a two‐bladed rotor are mounted by means of hinges k inclined to the plane of rotation, and are provided with auxiliary masses m hinged about axes M‐M. The restoring force on each mass is provided by the component of centrifugal force at right angles to the axis M‐M. According to the Provisional Specification, the mass provided for counter‐balancing a single‐bladed rotor may be located on an arm attached to the blade by flapping and/or ‘drag’ pivots so displaced from the axis of rotation that the natural frequency of the mass is twice that of the rotor.


(1950), "Month in the Patent Office", Aircraft Engineering and Aerospace Technology, Vol. 22 No. 12, pp. 379-379.




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