Polymer Based, Thermally Conductive and Erosion Resistant Boot Materials/Concepts for Rotor Blade Leading Edge Protection

The leading edge of the V-22 rotor blade is made of titanium and nickel abrasion strips bonded to the composite substrate. Although effective for rain erosion protection, nickel and titanium show poor sand erosion resistance. In addition, this metal and composite hybrid configuration limits working strain and fatigue life. This hybrid concept also hampers field serviceability and increases the operating and support cost of the rotor blade by inhibiting removal and replacement of the leading edge. It also necessitates frequent inspection to detect incipient fatigue cracks in the metal to ensure flight safety. The Navy is interested in removing the metallic leading edge strip and replacing it with a polymer based, field serviceable and thermally conductive erosion resistant boot materials/concepts directly over the existing composite substrate of the rotor blade. In this proposal, heat conductive fillers, fibers and fabrics will be combined with Hontek erosion resistant molding resins to form molded boot. Finite element analysis techniques will be used to determine the effect of fiber architecture and orientation on the conductivity of candidate molding resins. BENEFITS: It is anticipated that this effort will provide a light weight and conformable erosion protection system for the composite leading edge on current and emerging VTOL/STOL aircraft such as V-22 Osprey. This effort will eliminate the need for frequent inspection to detect incipient fatigue cracks in the metal leading edge, reduce acquisition and operating costs, enhance blade fatigue life, improve mission safety, reduce need for spares, simplify field serviceability and reduce total ownership cost (TOC). The molded erosion protection systems have universal applications to the entire fleet of helicopters and rotorcraft operated by the Navy and the Army.