Application Of Advanced Composites To Helicopter Airframe Structures

A preliminary design study has been conducted on the applicability of composite materials to helicopter fuselage structure. The CH-53D, a large, high-speed cargo and troop transport helicopter, was used as a baseline design for the study. The construction of the CH-53D airframe, primarily aluminum skin/stringers/frames, is representative of present generation helicopters. The study indicates that composite materials can be cost-effectively applied to primary helicopter airframe structures in the 1980's. Several composite design concepts were evaluated and compared with the baseline design on the basis of cost and weight. Graphite, Kevlar-49 and glass epoxy were used as the primary structural materials based on an evaluation of candidates which also included boron/epoxy and metal matrix materials. The most promising concept was an all-molded shell (skin/stringer/frame) modular construction. A segment of airframe shell, representative of this concept, has been experimentally fabricated, and a test program has been initiated to investigate the strength and stiffness properties of composite skin panels. A structural weight empty reduction of 18.5 percent was projected for the application of this concept to the CH-53D fuselage. Using this projection, a cost-effectiveness study was made for a fleet capability of 600 H-53 helicopters over a ten year life-cycle. The study projected a $202 million fleet life-cycle cost reduction; approximately $337,000 per helicopter.