Method for making a helicopter rotor blade

Claim 1

A method for making a helicopter rotor blade, comprising: (a) in a first longitudinally-extending trough-like mold having a pair of side walls and a curved bight joining said side walls, placing a longitudinally-extending counterweight member in the region of said bight, said counterweight member including a root member attached thereto, and a retention member projecting from the root member, laying a group of fibers in the mold atop the counterweight member and on each side of the root member, wrapping the group around said retention member, and laying at least a part of the wrapped around portion atop at least part of the group underneath it, whereby to form a bight in the group to provide for longitudinal restraint by the retention member, filling the interstitial spaces within the aforesaid with a curable initially liquid plastic material, curing said plastic material to form a monolithic spar with an outer shape determined by the mold where contact is made with the mold; (b) in a second and a third longitudinally-extending mold, each having a mold-wall with a concave curvature which is substantially the reverse of half of a convex air foil, layering sheets of reinforcing material on said mold wall and filling all interstitial spaces with a curable initially liquid plastic material, and curing said plastic material to form a first and a second skin section, each having an outer convex surface which is substantially one-half of an airfoil surface, with a leading edge and a trailing edge; (c) placing said cured skin sections in opposition to one another, with the spar member and a longitudinally-extending spacer member between them, and bonding said skin sections to said spar member and to said spacer member and their trailing edges to each other, while exerting a clamping force against said two skin sections.

Claim 2

A method for making a helicopter rotor blade, comprising: (a) in a first longitudinally-extending trough-like mold having a pair of side walls and a curved bight joining said side walls, placing a longitudinally-extending counterweight member in the region of said bight, said counterweight member including a root member attached thereto, and a retention member projecting from the root member, laying a group of fibers in the mold atop the counterweight member and on each side of the root member, wrapping the group around said retention member, and laying at least a part of the wrapped around portion atop at least part of the group underneath it, whereby to form a bight in the group to provide for longitudinal restraint by the retention member, filling the interstitial spaces within the aforesaid with a curable initially liquid plastic material, curing said plastic material to form a monolithic spar with an outer shape determined by the mold where contact is made with the mold; (b) in a second and a third longitudinally-extending mold, each having a mold-wall with a concave curvature which is substantially the reverse of half of a convex air foil, layering sheets of reinforcing material on said mold wall and filling all interstitial spaces with a curable initially liquid plastic material, and curing said plastic material to form a first and a second skin section, each having an outer convex surface which is substantially one-half of an airfoil surface, with a leading edge and a trailing edge; (c) placing said cured skin sections in opposition to one another, with the spar member and a longitudinally-extending spacer member between them, and bonding said skin sections to said spar member and to said spacer member and their trailing edges to each other, while exerting a clamping force against said two skin sections.