Innovative casting technique for determining heatshield mass loss in an erosive particle environment

An innovative technique has been developed for determining the mass loss due to single particle impacts in an ablative heatshield material. This technique is based on casting an easily molded, high density compound into the crater. Then by employing both weight differences and X-ray photos of the crater, the crater size and characteristics can be determined. This procedure has proven itself especially valuable with charred specimens where a preheat is employed to obtain high surface temperatures, and with specimens, charred or virgin, which are impacted at shallow angles. The X-ray photos have also been of value in that they delineate the crater surface area and depth to an extent that yields a correlation with velocity. This latter information has been of particular benefit to the determination of obscuration times, principally at shallow impact angles, where the use of mass loss ratios has proven inappropriate.