Nontangent, Developed Contour Bulkheads for a Single-Stage Launch Vehicle

Abstract

Dry weights for single-stage launch vehicles that incorporate nontangent, developed contour bulkheads are estimated and compared to a baseline vehicle with 1.414 aspect ratio ellipsoidal bulkheads. Weights, volumes, and heights of optimized bulkhead designs are computed using a preliminary design bulkhead analysis code. The dry weights of vehicles that incorporate the optimized bulkheads are predicted using a vehicle weights and sizing code. Two optimization approaches are employed. A structural-level method, where the vehicle's three major bulkhead regions are optimized separately and then incorporated into a model for computation of the vehicle dry weight, predicts a reduction of 4365 Ib (2.2%) from the 200,679-1b baseline vehicle dry weight. In the second, vehicle-level, approach, the vehicle dry weight is the objective function for the optimization. For the vehicle-level analysis, modified bulkhead designs are analyzed and incorporated into the weights model for computation of a dry weight. The optimizer simultaneously manipulates design variables for all three bulkheads to reduce the dry weight. The vehiclelevel analysis predicts a dry weight reduction of 5129 Ib, a 2.6% reduction from the baseline weight. Based on these results, nontangent, developed contour bulkheads may provide substantial weight savings for single stage vehicles. RIIR2 r Nomenclature= ratio of the local circumferential and meridional radii of curvature = normalized radius

Effect of specimen orientation and welding on the fracture and fatigue properties of 2195 Al–Li alloy

“…Its high specific strength and stiffness will improve lift efficiency, fuel economy, and performance, and would also increase payload capabilities of air and spacecrafts. This material has also been considered for use in the bulkheads of reusable single-stage-to-orbit launch vehicles [3] and combat ground vehicles [4]. The effects of composition, processing and aging conditions on the microstructure and tensile properties of this material have been extensively studied.…”