New Wings for the Huey

Composite rotor blades are advantageous, compared with metal blades, with respect to retirement life, repairability, ballistic tolerance, life-cycle cost, and aerodynamic tailorability. The UH-1 Composite Main Rotor Blade (CMRB) was designed to achieve these advantages. Specific design goals were replacement of the metal blades without other modification to the aircraft, and a 5 percent reduction in fuel flow at 105 knots. The blade is of fiberglass construction with integral attachment lugs at the blade root. The leading edge is composed of polyurethane which is designed to be field repairable and replaceable. The blade is tapered, in planform and uses advanced airfoils to achieve the required aerodynamic performance. The blade tooling and manufacturing had to accommodate the Army requirement of a leader/follower concept. Bell Helicopter Textron Incorporated (BHTI) being the leader and Boeing Vertol (BV) being the follower through the development program. Duplicate sets of matched cavity tools were produced for the leader/follower concept. Foam spar mandrels were used along with tooling devices to achieve the objective of avoiding the normal root boring and machining operations. Not all of these were successful. Contour tolerances were held to a large extent, but twist uniformity has proved to be a problem.