In this program, the effort will concentrate on attaining a complete understanding of the physics involved in inferring the shape of the forward surface of a carbon/carbon nosetip form the echo waveshape generated by an ultrasonic transmitter/receiver mounted on the back face. The highest priority will be focused on the ability to improve the interpretation of previous and future flight data using current UADS, while a secondary goal will be the ability to optimize the transmitted/receiver design for increased resolution of notes shape. The first phase studies the principles by which (1) acoustic waves are generated at the back surface by practical ultrasonic transmitters which can generate stress waves which are sufficiently intense to be detectable over the acoustic noise in the nosetip, (2) acoustic waves are propagated and reflected within the cold nosetip, and (3) the waves are affected by the high temperature present near the surface of the nosetip. This Phase I study will be primarily theoretical, based on existing mathematical models, but will be supported by selected laboratory tests to provide rough corroboration of the theory. Based on the general understanding of echo behavior in carbon/ carbon nosetips, the existing UADS noise sensors, and a proposed improved transmitters/receiver will be characterized in their ability to distinguish between nosetip shapes. This characterization will then be applied to the existing flight and ground test data to ASSVSS the probability of obtaining improved results from the Phase II experiments.
