INTEGRATION OF CARBON FIBER COMPOSITE MATERIALS INTO AIR-COOLED RECIPROCATING PISTON ENGINES FOR UAV APPLICATIONS

摘要

The United States Navy (USN) has shown an interest in the development of small displacement, reciprocating piston diesel engines for Unmanned Aerial Vehicles (UAVs). These engines avoid the logistic challenges of relying on gasoline-fueled UAVs, and have relatively low fuel consumption, but suffer from poor power-to-weight ratios. Reducing weight is of significant importance to UAVs to allow sufficient range and loitering times. Carbon fiber composites offer strength-to-weight benefits over the metal components currently used in piston engines. However, composite components have more restrictive operating temperatures. None of the known previous efforts aimed at integration of composites into engines has focused on air-cooled engines and on their potential benefits for UAVs. A small, single-cylinder air-cooled gasoline engine was chosen as a convenient test platform and surrogate for an air-cooled UAV engine. The crankcase and connecting rod from this engine were redesigned using a high fraction of carbon fiber in order to reduce weight. To develop the designs, steady-state temperature profiles were measured both internally and externally.