Helicopter rotor blade

Claim 1

A helicopter rotor blade having a longitudinal axis, an exterior airfoil configuration including an axially-extending leading edge, a top and a bottom surface, and a trailing edge, said blade comprising: a one-piece metal skin sheet bent to an airfoil shape to form the leading edge and said surfaces, the sheet having a dimension of thickness and a pair of axially extending edges; an axially extending one-piece metal former having oppositely facing walls having top and bottom surfaces extending laterally relative to the axis with respective surface configurations which are geometrically similar to the adjacent airfoil surface, said former having a uniform cross-section from end to end; retainer means integral with the former at its edge nearest to the leading edge comprising a pair of continuous flanges extending for the full length of the former, said flanges and the former forming a circularly arcuate channel, and said former having one open passage extending axially therethrough; a bonding material comprising a layer of spongy, volumetrically compressible, elastic foam and two adhesive layers, the layer of foam being sandwiched between the layers of adhesive material, one of said adhesive layers being bonded to each of said top and bottom surfaces, and the other to the skin sheet, whereby to bond the skin sheet to the former; an axially-extending one-piece metal counterweight member held by said retainer means, a wall of the counterweight member adjacent to the skin being geometrically similar to part of the leading edge of the airfoil, the skin being drawn around and against bonding material on the former and against the counterweight member and the said edges of the skin being fastened together at the trailing edge to form an axiallyextending joint laterally spaced from the former, whereby to form the skin to the said airfoil configuration, the specific gravity of the material of which the counterweight member is made being greater than the material of which the former is made, whereby to shift the center of gravity of the blade toward the leading edge, ahead of where it would have been had the counterweight and the former been made of the same material, the counterweight member being a circularly sectioned rod which extends for the full length of the former.