Skid Materials

The ASD sponsored an experiment that was essentially a product evaluation program of materials selected for use on the Dyna-Soar. Researchers bonded cermet (ceramic-metallic composite) runners to the rear landing-gear skids on the X-15 for five flights using X-15-3 in early 1964. Two additional flights were conducted using X-15A-2 to evaluate Inconel X skids. Engineers compared these data with those obtained on five earlier flights that used standard 4130-steel skids but carried additional instrumentation to measure landing loads:*206!

One of the outcomes of the study was an evaluation of skid wear. The amount of skid wear depended on the speed of the sliding, the hardness of the skid material, the strength of the surface material, and the sliding distance. For this evaluation, engineers measured the thickness of the X-15 skids after each flight, generally near the point of attachment to the main strut. The difficulties involved in removing and reinstalling the skids in a timely manner precluded weighing them. The cermet skids experienced a considerable amount of wear during the first landing because of the soft outer layer of copper-nickel, but showed less wear on later landings because the tungsten-carbide chips were uncovered.-1207

The data for the 4130-steel skids showed an increasing amount of skid wear as the sliding distance increased beyond 6,400 feet. The wear characteristics of the Inconel X skids were not determined because of the difficulty of measuring the chemically milled areas inside the skid. However, preliminary data indicated a wear resistance superior to that of the 4130 steel, with or without a cermet coating.-208