Molecular Physics of Elementary Processes relevant to Hypersonics: atom-molecule, molecule-molecule and atom-surface processes.

In the present chapter some prototype gas and gas-surface processes occurring within the hypersonic flow layer surrounding spacecrafts at planetary entry are discussed. The discussion is based on microscopic dynamical calculations of the detailed cross sections and rate coefficients performed using classical mechanics treatments for atoms, molecules and surfaces. Such treatment allows the evaluation of the efficiency of thermal processes (both at equilibrium and nonequilibrium distributions) based on state-to-state and state specific calculations properly averaged over the population of the initial states. The dependence of the efficiency of the considered processes on the initial partitioning of energy among the various degrees of freedom is discussed.

The BCD transient recorder revisited: firmware for the ISA-to-USB bridging card and software for the graphical user interface

This report describes recent updates to the custom-built data-acquisition hardware operated by the Center for Hypersonics. In 2006, an ISA-to-USB bridging card was developed as part of Luke Hillyard's final-year thesis. This card allows the hardware to be connected to any recent personal computers via a (USB or RS232) serial port and it provides a number of simple text-based commands for control of the hardware. A graphical user interface program was also updated to help the experimenter manage the data acquisition functions. Sampled data is stored in text files that have been compressed with the gzip for mat. To simplify the later archiving or transport of the data, all files specific to a shot are stored in a single directory. This includes a text file for the run description, the signal configuration file and the individual sampled-data files, one for each signal that was recorded.

New calibration technique for multiple-component stress wave force balances

Force measurement in hypervelocity expansion tubes is not possible using conventional techniques. The stress wave force balance technique can be applied in expansion tubes to measure forces despite the short test times involved. This paper presents a new calibration technique for multiple-component stress wave force balances where an impulse response created using a load distribution is required and no orthogonal surfaces on the model exist.. This new technique relies on the tensorial superposition of single-component impulse responses analogous to the vectorial superposition of the calibration loads. The example presented here is that of a scale model of the Mars Pathfinder, but the technique is applicable to any geometry and may be useful for cases where orthogonal loads cannot be applied.

Interview with Hans G. Hornung

An interview in two sessions, June and July 2014, with Hans Georg Hornung, Clarence L. Johnson Professor of Aeronautics, emeritus, in the Division of Engineering and Applied Science. Dr. Hornung describes the origins of the German Templer Colony in Palestine and his upbringing there before and during World War II. Family moves to Templer settlement, Melbourne, Australia, 1948. He attends technical college; University of Melbourne; master’s in engineering, 1962. Researcher, Aeronautical Research Laboratories, Melbourne; PhD, Imperial College, London, 1965. He recalls his academic career at the Australian National University, Canberra (1967-1980); his interest in hypersonics; building free-piston shock tunnel with Raymond Stalker. Sabbatical in Darmstadt with Ernst Becker. Seven years as director of fluid-mechanics institute of the DLR [Deutsches Zentrum für Luft- und Raumfahrt], in Göttingen. Comes to Caltech in 1987 to succeed Hans W. Liepmann as director of GALCIT [Graduate Aerospace Laboratories, California Institute of Technology]. Recalls his various aero colleagues, his work with Rocketdyne on Caltech’s T5 (successor to Canberra’s T3 shock tunnel) and Ludwieg tube, collaboration with JPL on space program, and work with graduate students Simon Sanderson and Eric Cummings. Discusses his involvement in various scientific societies and his current activities and continuing research as an emeritus professor.