| Popis: |
Dry weights for a SSTO vehicle which incorporates 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 weight of a vehicle which incorporates the optimized bulkheads is 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 vehcile dry weight, predicts a reduction of 4365 lb (2.2 percent) from the 200,679 lb baseline vehicle dry weight. In the second, vehicle-level approach, the vehicle dry weight is the objective function for the optimization. During the vehicle-level analysis, modified bulkhead designs are first analyzed, then incorprated 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 vehicle-level analysis predicts a dry weight reduction of 5129 lb, a 2.6 percent reduction from the baseline value. These results suggest that nontangent, developed conour bulkheads may provide substantial weight savings for SSTO vehicles. |
