FLIGHT TEST ABLATION MONITORING OF NATIONAL AERO-SPACE PLANE (NASP) ENGINE COMPONENTS BY SURFACE LAYER ACTIVATION

DEVELOPMENT OF ENGINES CAPABLE OF PROPELLING VEHICLES AT HYPERSONIC SPEED REQUIRES MATERIALS AND DESIGNS CAPABLE OF PERFORMING IN EXTREME THERMAL ENVIRONMENTS. IN A PROTOTYPE VHEICLE IT WILL BE NECESSARY TO NON-OBTRUSIVELY INSTRUMENT THE ENGINE TO MONITOR PERFORMANCE, DURABILITY, AND STRUCTURAL INTEGRITY OF NEW COMPONENTS. SEVERAL TECHNIQUES FOR PRECISE IN-FLIGHT REMOTE MONITORING OF SURFACE LOSS WERE DEVELOPED BY SPIRE IN THE EARLY 1970S TO MEASURE ABLATION OF MISSILE NOSE CONES DURING REENTRY. ONE APPROACH, TERMED SURFACE LAYER ACTIVATION (SLA), USES RADIONUCLIDES PRODUCED BY PARTICLE ACCELERATOR BOMBARDMENT AS SURFACE MARKERS. ACTIVITY REDUCTION REMOTELY MEASURED BY A MINIATURIZED GAMMA RAY DETECTION SYSTEM IS USED TO DEDUCE THE AMOUNT OF SURFACE MATERIAL REMOVED WHILE IN FLIGHT IN REAL TIME. THIS APPROACH HAS SINCE BEEN FOUND TO BE IDEAL FOR UNOBTRUSIVE MEASUREMENT OF MICROMETER-SCALE WEAR IN OPERATING SYSTEMS, WITH SUCCESSFUL APPLICATION TO ENGINE COMPONENTS SUCH AS PISTONS, CYLINDERS, RINGS, LINERS, BEARINGS, CAMS, AND GEARS. THE PROPOSED RESEARCH WILL INVESTIGATE THE FEASIBILITY OF ADAPTING SLA TO IN-FLIGHT MONITORING OF CRITICAL ENGINE COMPONENTS IN HYPERSONIC VEHICLES.