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This final report, dated September 10, 1996, was prepared by the Research Triangle Institute for the Department of the Air Force's 45th and 30th Space Wing safety offices. Titled Modeling Unlikely Space-Booster Failures in Risk Calculations, it shows how rare Mode-5 failures, in which a rocket veers well off its intended flight line, are modeled in the DAMP risk-analysis program. An appendix lists Atlas, Delta, Titan and Thor launch and failure histories through August 1996.
From the source:Release of 2026-05-08 Incident: 9/10/96, N/A. This report describes the Modeling of Unlikely Space-Booster Failures in Risk Calculations, documenting historical launch failure modes and recommending corrective actions to address them using novel modelling techniques.
Table 2. Predicted Failure Probabilities for Representative Configurations Vehicle Flight Phase Filter Technic ue Sample Failures /Total Equal Weight Index Count Expon. F =0.99 Expon. F = 0.98 Expon F = 0.97 Atlas 0 0 0 0 0 0 0/7 0-1 0.0256 0.0253 0.0245 0.0219 0.0186 4/156 0-2 0.0449 0.0385 0.0387 0.0313 0.0243 7/156 0-3 0.0769 0.0715 0.0714 0.0643 0.0568 12/156 0-4 0.0833 0.0811 0.0801 0.0740 0.0663 13/156 0-5* 0.1090 0.1100 0.1078 0~1019 0.0929 17/156 Delta 0 0 0 0 0 0 0/125 0-1 0.0160 . 0.0126 0.0134 0.0104 0.0075 2/125 0-2 0.0160 0.0126 0.0134 0.0104 0.0075 2/125 0-3 0.0160 0.0126 ·o.0134 0.0104 0.0075 2/125 0-4 0.0160 0.0126 0.0134 0.0104 0.0075 2/125 0-5* 0.0640 0.0447 0.0535 0.0469 0.0442 8/125 Titan 0 0.0306 0.0210 0.0225 0.0292 0.0352 3/98 0-1 0.0234 0.0305 0.0314 0.0403 0.0470 4/171 0-2 0.0409 0.0496 0.0514 0.0642 0.0750 7/171 0-3 0.0526 0.0581 0.0597 0.0689 0.0773 9/171 0-4 0.0526 0.0581 0.0597 0.0689 0.0773 9/171 0-5* 0.1111 0.1167 0.1188 0.1284 0.1358 19/171 * Includes response mode 'NA' It is apparent from the data in Table 2 that estimates of future vehicle reliability depend on the filtering (i.e., weighting) technique applied. Since there are many ways to perform the filtering, all generally producing slightly different results, the choice of method to use in deriving empirical failure probabilities cannot be totally objective. Subjective decisions must also be made about which past configurations to consider as representative of future vehicles, which flight tests to include_ in the sample, how to weight the individual flights, and, in unusual cases, whether to consider a flight a success or a failure, and to which flight phase to attribute a failure. Except for data weighting (i.e., choice of filter), these decisions were made for Atlas, Delta, and Titan before computing the failure probabilities shown in Table 2. • For Atlas and Delta, it can be seen from Table 2 that the predicted failure probabilities computed. with the exponential filter decrease as the value of F decreases. Since a decreasing F means more emphasis on recent data and less emphasis on the old, the launch reliability for these vehicles is apparently improving. The reverse seems to be true for Titan, suggesting either that Titan reliability is not improving or, possibly, that improvements that have been or are being made to the vehicle are not yet fully reflected in the test· results. For Atlas and Delta, the computed failure probabilities based on equal weighting are higher than for all other filters, and the predicted failure 9/10/96 17 RTI
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Report, from the pursue collection. The PDF is mirrored here; the original link is above. 181 pages are in the text index: search them above, or from the library's search.