Mathias, Donovan — Page 3 | Engineering Papers

NASA NTRS2006

Simulation Assisted Risk Assessment: Blast Overpressure Modeling

A probabilistic risk assessment (PRA) approach has been developed and applied to the risk analysis of capsule abort during ascent. The PRA is used to assist in the identification of modeling and simulation applications that can significantly impact the understanding of crew risk during this potentially dangerous maneuver. The PRA approach is also being used to identify the appropriate level of fidelity for the modeling of those critical failure modes. The Apollo launch escape system (LES) was chosen as a test problem for application of this approach. Failure modes that have been modeled and/or simulated to date include explosive overpressure-based failure, explosive fragment-based failure, land landing failures (range limits exceeded either near launch or Mode III trajectories ending on the African continent), capsule-booster re-contact during separation, and failure due to plume-induced instability. These failure modes have been investigated using analysis tools in a variety of technical disciplines at various levels of fidelity. The current paper focuses on the development and application of a blast overpressure model for the prediction of structural failure due to overpressure, including the application of high-fidelity analysis to predict near-field and headwinds effects.

Lawrence, Scott L.↗

NASA NTRS1992

TBD(exp 3)

When asked by the Aeronautical Engineering staff to design a viable supersonic commercial transport, most of the students were well aware that Boeing, McDonnell Douglas, and other aircraft companies had been studying a cadre of transports for more than 30 years and had yet to present a viable aircraft. In the spirit of aviation progress and with much creative license, the TBD design team spearheaded the problem with the full intention of presenting a marketable high speed civil transport in spring of 1992. The project commenced with various studies of future market demands. With the market expansion of American business overseas, the airline industry projects a boom of over 200 million passengers by the year 2000. This will create a much higher demand for time efficient and cost effective inter-continental travel; this is the challenge of the high speed civil transport. The TBD(exp 3), a 269 passenger, long-range civil transport was designed to cruise at Mach 3.0 utilizing technology predicted to be available in 2005. Unlike other contemporary commercial airplane designs, the TBD(exp 3) incorporates a variable geometry wing for optimum performance. This design characteristic enabled the TBD(exp 3) to be efficient in both subsonic and supersonic flight. The TBD(exp 3) was designed to be economically viable for commercial airline purchase, be comfortable for passengers, meet FAR Part 25, and the current FAR 36 Stage 3 noise requirements. The TBD(exp 3) was designed to exhibit a long service life, maximize safety, ease of maintenance, as well as be fully compatible with all current high-traffic density airport facilities.

Baughan, Jim↗