Patent ID: 8632310

Claim:
A helicopter rotor blade, comprising: a structural composite skin defining a cavity therein; a composite spar disposed within the cavity and adhesively bonded to the skin, a portion of the spar exhibiting a C-shape in cross section; and a foam core disposed within the cavity and adhesively bonded to the skin; a composite tube disposed within the cavity and formed from a plurality of plies urged against and adhesively bonded to the composite spar, the foam core, and the skin, so as to provide a compaction pressure internal to the blade during curing of the blade, the composite tube and extending between the composite spar and the foam core, the composite tube being formed from the expansion of a mandrel; wherein the structural composite skin forms an external, closed box structure configured to transmit mechanical loads encountered by the rotor blade; and wherein the structural composite skin is configured for providing significant stiffness and mechanical strength to the rotor blade.