A New Methodology for Calculating Launch Vehicle Ascent Loads

Determining an effective structural design of a launch vehicle is critical to both mission success and crew safety. In order to evaluate the adequacy of a launch vehicle?s structural design, the ascent loads experienced by the vehicle must be determined. Computation of the ascent loads is a complex, multi-disciplined undertaking that involves an assessment of both natural and induced environments. Currently, ascent loads are calculated primarily using a somewhat restrictive constant Mach number squatcheloid approach. A method to compute the ascent loads of a launch vehicle through a direct coupling of the six-degree-of-freedom trajectory simulation with a time correlated flexible body simulation of the structure is proposed. Load dispersions due to the statistical uncertainties associated with both environmental effects (e.g., winds) as well as vehicle uncertainties (e.g., thrust misalignment) may be assessed directly from a set of Monte Carlo runs of the synchronized trajectory and loads simulations. The Phase I research is directed at developing the necessary algorithms and providing a proof-of-concept simulation. During Phase II, a complete modular computational framework will be developed that will integrate the 6DOF trajectory tools with the loads prediction software, allowing for a more accurate and unified loads analysis of the vehicle.