ANTENNA WINDOW HIGH TEMPERATURE PROPERTY MEASUREMENT

ACCURATE PREDICTIONS OF THE WINDOW/HEATSHIELD ABLATED SHAPE AND IN-DEPTH HEAT TRANSFER ARE VITAL TO ENSURE VEHICLE SURVIVAL AND THE ANTENNA WINDOW'S TRANSMISSION PERFORMANCE. THESE PREDICTIONS REQUIRE ACCURATE THERMOPHYSICAL PROPERTY DATA ON THE MATERIAL. SOME OF THE THERMOPHYSICAL DATA CURRENTLY USED AT HIGH TEMPERATURE HAS A HIGH UNCERTAINTY AS IT HAS BEEN EXTRAPOLATED FROM LOW TEMPERATURE DATA OR HAS BEEN PREDICTED FROM ANALYSES OF WINDOW PERFORMANCE TESTING IN WHICH THERE ARE A NUMBER OF UNKNOWN VARIABLES. THE OBJECTIVE OF THIS PROPOSED EFFORT IS TO DEVELOP THE CAPABILITY OF OBTAINING THIS DATA AT HIGH TEMPERATURES. IN PHASE I, THE OBJECTIVE WILL BE TO EVALUATE CANDIDATE TEST TECHNIQUES, SELECT THE TECHNIQUES MOST SUITABLE, AND PREPARE A PRELIMINARY DESIGN OF THE TEST HARDWARE AND PROCEDURES. THIS WILL INCLUDE MEASUREMENT SYSTEMS WITH THE CAPABILITY FOR MEASURING THE VISCOSITY, DENSITY, AND THERMAL COEFFICIENT OF EXPANSION AT TEMPERATURES UP TO, AND EXCEEDING IF POSSIBLE, 5000 DEG R. THE PHASE II EFFORT WILL INCLUDE THE ASSEMBLY OF THE MEASUREMENT SYSTEMS SELECTED, AN EVALUATION OF THE ASSEMBLED SYSTEMS, AND MATERIAL CHARACTERIZATION TESTING. IN ADDITION, THE FEASIBILITY OF DEVELOPING MEASUREMENT TECHNIQUES FOR OTHER PROPERTIES WILL BE EVALUATED.