An Air-Launched Hypersonic Vehicle Performance Study

Author(s):  
Con Doolan
Author(s):  
Kyle C. Markell ◽  
Keith M. Brewer ◽  
Michael R. von Spakovsky

The results of the application of an exergy-based method to highly dynamic, integrated hypersonic vehicle concepts are presented. Conventional aircraft systems and sub-systems traditionally are designed relying heavily on rules of thumb, individual experience, and rather simple, non-integrated tradeoff analyses, which are highly dependent on the evolutionary nature of vehicle development. In contrast, hypersonic vehicles may contain new sub-systems and revolutionary concepts for which there is no existing database to support an evolutionary synthesis/design approach. Thus, a simple tradeoff analysis becomes virtually impossible, particularly in light of the highly integrated, non-linear relationship between hypersonic vehicle sub-systems and the complexity of the missions involved. Therefore, the departure from existing databases and experience levels requires an integrated approach and a common metric for the synthesis/design of hypersonic vehicles to achieve an optimal synthesis/design. To that end, an exergy-based mission integrated methodology is introduced and compared to traditional measures (including a non-integrated approach) by applying these to the synthesis/design and operational optimization of a hypersonic vehicle configuration comprised of an airframe and a propulsion sub-system (consisting of inlet, combustor, and nozzle components). Results of these optimizations are presented and include a quantification of all vehicle losses in terms of exergy lost or destroyed, providing a common metric for the vehicle designer to identify where the largest improvements in vehicle performance can be made. Furthermore, via a number of parametric studies, the impacts of the design and operational decision variables on exergy destruction are discussed.


Author(s):  
Michael Holden ◽  
Timothy Wadhams ◽  
Gregory Smolinski ◽  
Matthew MacLean ◽  
John Harvey ◽  
...  

2014 ◽  
Vol 45 (3) ◽  
pp. 239-245 ◽  
Author(s):  
Robert J. Calin-Jageman ◽  
Tracy L. Caldwell

A recent series of experiments suggests that fostering superstitions can substantially improve performance on a variety of motor and cognitive tasks ( Damisch, Stoberock, & Mussweiler, 2010 ). We conducted two high-powered and precise replications of one of these experiments, examining if telling participants they had a lucky golf ball could improve their performance on a 10-shot golf task relative to controls. We found that the effect of superstition on performance is elusive: Participants told they had a lucky ball performed almost identically to controls. Our failure to replicate the target study was not due to lack of impact, lack of statistical power, differences in task difficulty, nor differences in participant belief in luck. A meta-analysis indicates significant heterogeneity in the effect of superstition on performance. This could be due to an unknown moderator, but no effect was observed among the studies with the strongest research designs (e.g., high power, a priori sampling plan).


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