Evaluation of Two Ballistically Tolerant Forward Bell Crank Concepts for the CH-47 Helicopter
ARMY AIR MOBILITY RESEARCH AND DEVELOPMENT LAB FORT EUSTIS VA EUSTIS DIRECTORATE
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The objective of this program was to investigate a ballistically tolerant, lightweight, low-cost flight control system for the forward rotor control of the CH-47 helicopter. Both 6Tetro-Core6 a three- dimensional, filament-wound space structure AND TUBULAR FIBERGLASS CLOTH CONCEPTS WERE EVALUATED. Weights of less than 2 pounds were achieved, as compared to 3.4 pounds for the existing metallic bell crank. Of the two basic concepts, 6Tetra- Core6 offers structural effectiveness superior to the existing metallic components. It was found that venting reduced the damage on the exit side of the glass cloth specimens. In addition to the bell crank, ballistically tolerant push rods and bearings of FRPepoxy were investigated. Limited research on the components indicates favorable tolerance to ballistic impact, along with potential weight and cost savings.