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Analysis and design of total temperature probes for accurate measurements in hot, high-speed flows remains a topic of great interest in aerospace propulsion and a number of other engineering areas. Despite an extensive prior literature on the subject, prediction of error sources from convection, conduction and radiation is still an area of great concern. For hot-flow conditions, the probe is normally mounted in a cooled support, leading to substantial axial conduction along the length of the probe. Also, radiation plays a very important role in most hot, high-speed conditions. One can apply detailed computational methods for simultaneous convection, conduction and radiation heat transfer, but such approaches are not suitable for rapid, routine analysis and design studies. So, there is still a place for low-order approximate methods, and that is the subject of this paper.

1 Most traditional methods and equations for estimating the structural and nonstructural weights and aerodynamics used at the aircraft conceptual design phase are empirical relations developed for conventional tube-and-wing aircraft. In a computation-heavy design process, such as Multidisciplinary Design and Optimization (MDO) simplicity of calculation is paramount, and for conventional configurations the aforementioned approaches work well enough for conceptual design. But, for non-traditional designs such as strut-braced winged aircraft, empirical data is generally not available and the usual methods can no longer apply. One solution to this is a movement toward generalized physics-based methods that can apply equally well to conventional or non-traditional configurations.

This paper details the multidisciplinary design optimization (MDO) of a strut-braced wing aircraft and its benefits relative to the cantilever wing configuration. The multidisciplinary design team is subdivided into aerodynamics, structures, aeroelasticity and synthesis of the various disciplines. The aerodynamic analysis consists of simple models for induced drag, wave drag, parasite drag and interference drag. The interference drag model is based on detailed computational fluid dynamics (CFD) analyses of various wing-strut intersection flows. The wing structural weight is partially calculated using a newly developed wing bending material weight routine that accounts for the special nature of strut-braced wings. The remaining components of the aircraft weight are calculated using a combination of NASA’s Flight Optimization System (FLOPS) and Lockheed Martin Aeronautical System formulas.