CARBON-CARBON/REFRACTORY METAL HEAT PIPES FOR LEADING EDGE COOLING ON REUSABLE HYPERSONIC VEHICLES

REUSABLE HYPERSONIC VEHICLES, OPERATING WELL BEYOND THE PERFORMANCE ENVELOPE OF CONVENTIONAL AIRCRAFT, WILL ENCOUNTER EXTREMELY HIGH TEMPERATURES; DURING REENTRY, THE NOSE WILL EXPERIENCE IN EXCESS OF 5000 DEGREES FAHRENHEIT, AND LEADING-EDGE SURFACES WILL FEEL NEARLY 3500 DEGREES FAHRENHEIT. CLEARLY, LIGHTWEIGHT LEADING-EDGE COOLING CONCEPTS ARE NEEDED TO WITHSTAND SUCH HIGH TEMPERATURES. THE HEAT PIPE--A QUASIPASSIVE, SELF-CONTAINED, LOW-MAINTENANCE DEVICE--SHOULD BE WELL-SUITED FOR LEADING-EDGE COOLING APPLICATIONS. THIS PHASE I PROJECT WILL DEMONSTRATE THE FEASIBILITY OF FABRICATING A STRAIGHT D-SHAPED HEAT PIPE BY CHEMICAL VAPOR DEPOSITION (CVD) AND INFILTRATION (CVI). THE WICK WILL BE A REFRACTORY-METAL-INFILTRATED CARBON FOAM, AND THE CONTAINER WALLS WILL BE A THIN REFRACTORY METAL SKIN OR SHELL. COMPATIBILITY OF THE CHOSEN REFRACTORY-METAL WITH CARBON-CARBON WILL BE ESTABLISHED, AND A CVD TECHNIQUE FOR PRODUCING CONTAINER WALLS OF MINIMUM THICKNESS FOR WEIGHT REDUCTION WILL BE DEFINED. AT THE END OF THE PROJECT, THE HEAT PIPE WILL BE FILLED WITH A WORKING FLUID AND TESTED FORISOTHERMAL OPERATION. THE RESULT WILL BE THE DEFINITION OF TECHNIQUES FOR FABRICATING ACTUAL LEADING-EDGE HEAT PIPE CONFIGURATIONS IN PHASE II AND BEYOND. REUSABLE HYPERSONIC VEHICLES, OPERATING WELL BEYOND THE PERFORMANCE ENVELOPE OF CONVENTIONAL AIRCRAFT, WILL ENCOUNTER EXTREMELY HIGH TEMPERATURES; DURING REENTRY, THE NOSE WILL EXPERIENCE IN EXCESS OF 5000 DEGREES FAHRENHEIT, AND LEADING-EDGE SURFACES WILL FEEL NEARLY 3500 DEGREES FAHRENHEIT. CLEARLY, LIGHTWEIGHT LEADING-EDGE COOLING CONCEPTS ARE NEEDED TO WITHSTAND SUCH HIGH TEMPERATURES. THE HEAT PIPE--A QUASIPASSIVE, SELF-CONTAINED, LOW-MAINTENANCE DEVICE--SHOULD BE WELL-SUITED FOR LEADING-EDGE COOLING APPLICATIONS. THIS PHASE I PROJECT WILL DEMONSTRATE THE FEASIBILITY OF FABRICATING A STRAIGHT D-SHAPED HEAT PIPE BY CHEMICAL VAPOR DEPOSITION (CVD) AND INFILTRATION (CVI). THE WICK WILL BE A REFRACTORY-METAL-INFILTRATED CARBON FOAM, AND THE CONTAINER WALLS WILL BE A THIN REFRACTORY METAL SKIN OR SHELL. COMPATIBILITY OF THE CHOSEN REFRACTORY-METAL WITH CARBON-CARBON WILL BE ESTABLISHED, AND A CVD TECHNIQUE FOR PRODUCING CONTAINER WALLS OF MINIMUM THICKNESS FOR WEIGHT REDUCTION WILL BE DEFINED. AT THE END OF THE PROJECT, THE HEAT PIPE WILL BE FILLED WITH A WORKING FLUID AND TESTED FORISOTHERMAL OPERATION. THE RESULT WILL BE THE DEFINITION OF TECHNIQUES FOR FABRICATING ACTUAL LEADING-EDGE HEAT PIPE CONFIGURATIONS IN PHASE II AND BEYOND.