Parametric dynamic load prediction of a narrow gauge rocket sled

Dynamic load prediction of rocket sleds has been of interest to sled designers and analysts since the inception of the Holloman High Speed Test Track, (HHSTT). Dynamic loading along with thrust and aerodynamic loading is a primary contributor to sled design load cases. Dynamic loading comes directly from the rocket sled traversing the gap between the slipper and rail and the resulting sliding impacts. The current study investigates the prediction of narrow gauge sled dynamic loads by applying a systematic process of modeling validation, design parameter variation and dynamic load correlation.;Numerical modeling was employed to simulate the Land Speed Record (LSR) test and the model data was validated by comparing it to the data taken from the sled during the LSR test. Modeling methods validated against the test data were applied to a reduced complexity narrow gauge sled representing a generic version of the LSR sled. Design parameters were identified that contributed to the generation of dynamic loading. The design parameters are: sled mass, slipper gap, vertical rail roughness, lateral rail roughness, vertical sled natural frequency, lateral sled natural frequency, torsional sled natural frequency, and sled velocity. Peak dynamic load results (from evaluating the reduced complexity model while varying the design parameter values over high, low, and typical ranges) were computed at the sled center of Gravity (CG). This peak dynamic loading, eta force, constituted the dynamic load prediction. The correlation of eta to its respective design parameters showed that a multivariate interpolation method was the most accurate method to relate eta force to its respective design parameters. The study revealed a heavy dependence of dynamic load on velocity, rail roughness, slipper gap, and translational sled natural frequencies. The study also showed a favorable comparison of eta force prediction over previously used methods at the HHSTT.