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During testing at the Holloman High Speed Test Track (HHSTT) and other tracks, “sleds” (means to carry the unit under test and propulsion) are constrained to the rail by metal “slippers” that wrap aro... During testing at the Holloman High Speed Test Track (HHSTT) and other tracks, “sleds” (means to carry the unit under test and propulsion) are constrained to the rail by metal “slippers” that wrap around the rail head and ensure the sled follows the trajectory defined by the track. Slipper wear tribology, continues to be a limitation for certain sled tests, especially during high-speed tests or when the sled is required to travel longer distances. The physical interaction between the slippers and the rail during sled testing is not well understood. Excessive slipper wear (to the point where the sled could leave the rail) is thought to be caused by large forces generated from impacts between the slippers and the rail, friction forces applied over time, and potentially other interaction effects. High speeds and long travel distances tend to increase slipper wear, but the accurate prediction of slipper wear has proven to be challenging. Slippers that wear to the point of structural failure are of most concern, especially with higher velocities and longer travel distances expected in the future. One of the central problems in the development of wear-resistant materials for use in slippers is the lack of a validated, high-speed wear prediction model. Without a validated prediction model the amount of wear slippers are likely to experience during a sled test cannot be accurately predicted. Atch 1 Request Due Date: 22 May 2025, 10:00 AM CST