Vertical Air Launch Sled (VALS) l/32~(nd) Scaled Flight Test Article and Experimentally Validated Stability Predictions

摘要

This paper details recent progress made on performance predictions using reduced scaled test vehicles for a new unique air launch concept called the Vertical Air Launch Sled (VALS). Through use of scaling parameters such as Froude, Reynolds, and Mach numbers, a 1/32~(nd) scale model was found to be justifiable for dynamic testing. A 1/32~(nd) scale fully functional model was manufactured and vibration tested. Three accelerometer placements were used to test for longitudinal, lateral, and multi-axial modes on the vehicle. Natural frequencies and coupled modes were estimated by plots of the frequency response functions. The stability of the VALS is analyzed by estimation of stability derivatives, incorporating them into linearized longitudinal equations of motion, and calculating the eigenvalues and eigenvectors for four configurations of VALS with a launch vehicle (LV): (Config 1: "wings-down" with LV attached, Config 2: "wings-up" with LV attached, Config 3: "wings up" with LV detached, and Config 4: "wings down" with LV detached). Two different scales were studied, a l/32~(nd) scale VALS model and a full scale VALS model. Eigenvalues confirm that the full scale system is stable longitudinally for all the configuration phases.