Novel Main Transmission Design Concepts

Rotary-wing aircraft use transmission systems to transfer power from the engines to the rotor system. These transmissions employ lightweight high strength metals to reduce overall aircraft weight. The Navy and the helicopter industry would like to further decrease aircraft weight, as an increase in performance can be achieved for every pound of weight reduction. Composites offer advantages over metals in that they can achieve equal or higher strengths with less weight. The Bell V-22 tiltrotor uses higher power, lower volume transmissions than those used in conventional helicopters. These transmissions produce more heat and depend on the metallic transmission housing to dissipate this energy. Typically, commercially available composites systems have low thermal conductivity properties. While composite transmission components may be able to withstand the dynamic and thermal stresses produced by the V-22 transmission, transmission failure or premature wear could result due to the inability of the composite material system to dissipate heat adequately. In this Phase II effort, Texas Research Institute Austin, Inc., with teaming partner Bell Helicopter Textron, Inc., proposes to develop cost effective, lightweight, thermally conductive composite material systems that will meet design requirements and dissipate heat sufficiently to be used in a military helicopter transmission environment.