Reynolds Number, Compressibility, and Leading-Edge Bluntness Effects on Delta-Wing Aerodynamics
An overview of Reynolds number, compressibility, and leading edge bluntness effects is presented for a 65 degree delta wing. The results of this study address both attached and vortex-flow aerodynamics and are based upon a unique data set obtained in the NASA-Langley National Transonic Facility (NTF) for i) Reynolds numbers ranging from conventional wind-tunnel to flight values, ii) Mach numbers ranging from subsonic to transonic speeds, and iii) leading-edge bluntness values that span practical slender wing applications. The data were obtained so as to isolate the subject effects and they present many challenges for Computational Fluid Dynamics (CFD) studies.
The National Transonic Facility: A Research Retrospective
An overview of the National Transonic Facility (NTF) from a research utilization perspective is provided. The facility was born in the 1970s from an internationally recognized need for a high Reynolds number test capability based on previous experiences with preflight predictions of aerodynamic characteristics and an anticipated need in support of research and development for future aerospace vehicle systems. Selection of the cryogenic concept to meet the need, unique capabilities of the facility, and the eventual research utilization of the facility are discussed. The primary purpose of the paper is to expose the range of investigations that have used the NTF since being declared operational in late 1984; limited research results are included, though many more can be found in the references.
A Language Element for Compression Coding
It has been a matter of convenience that language codes have utilized statistical aspects of easily identified language elements such as letters and words although there is no a priori reason to indicate that these are the natural elements of coding in the brain. Other aspects of total redundancy including m-word elements and grammatical constraints are considered in this paper. Conditions are established under which greater compression is achieved by mapping m-words from a source language into a single code word. The results of tests which utilized several language elements are reported and suggestions are made for utilizing some of the techniques of mechanical translation to achieve maximum compression.