20-Jan-2013 Source: HeliHub.com
Sikorsky have been granted patent number 8,353,673 for “A main rotor blade assembly includes a main spar with an integral cuff. The main spar is directly to a rotor hub assembly through the integral cuff”. Two particular sections of interest from the official US Patent & Trademark Office website posting are listed below
Background of the Invention
The present invention relates to a rotary wing aircraft main rotor blade, and more particularly to a main rotor blade with a cuff integral with the spar.
Rotary-wing aircraft rotor blades often include a composite or metallic main rotor spar of a constant chord and constant wall thickness. To attach the rotor spar to a hub assembly, a separate root end cuff is attached to an inboard section of the main rotor spar. The cuff is conventionally manufactured of a titanium forging or a composite root laminate sized to match an outer mold line of the main rotor spar. The root end cuff is attached to the main rotor spar through a multiple fastener configuration, each fastener of which must be torqued to a required standard.
Although effective, the separate root end cuff assembly and related hub componentry may result in a weight and life cycle penalty as the multiple of components are duplicated on each rotor blade assembly.
Summary of the Invention
A main rotor blade assembly according to an exemplary aspect of the present invention includes: a main spar formed with an integral cuff.
A rotary wing aircraft according to an exemplary aspect of the present invention includes: a rotor hub assembly; a main spar which comprises a root section and an main section, the root section forms an integral cuff, the integral cuff having a first hub mount aperture and a second hub mount aperture; a first pin which passes through the first aperture to mount the main spar to the rotor hub assembly; and a second pin which passes through the second aperture to mount the main spar to the rotor hub assembly.
A method of mounting a main rotor blade assembly according to an exemplary aspect of the present invention includes: attaching an integral cuff directly to a rotor hub assembly.