The results of an experimental study of blunt-body heat-transfer problems during entry into planetary atmospheres are presented. Equilibrium gas radiance and convective heattransfer rates were measured in several CO2-N 2 gas mixtures over a simulated flight velocity range (approximately) of 30,000 to 45,000 fps. An electrically driven shock tube was used to provide the simulated hypervelocity flight conditions. An unresolved problem concerning the apparent influence of gage surface material on measured convective heat-transfer rates is identified and discussed. The properties and performance of a total radiation cavity gage, used to obtain the gas radiance data, are described. It is shown that species concentrations in a CO2-N2 mixture have only a small effect on convective heating rates. A similar conclusion for gas radiance is inferred at flight velocities above 32,000 fps. The experimental results are compared with appropriate theoretical predictions and other experimental data and are used to predict stagnation-point radiative and convective heating for Venus entry trajectories. Nomenclature= calorimeter gage thickness ra = mass q -heat-transfer rate t = time y e -entry angle down from horizontal X = wavelength p = density Subscripts 1 = initial driven tube conditions 2 = behind incident shock W = wall R = radiative c -convective e = entry conditions (also equilibrium) / = flight conditions 0 = reference conditions * = stagnation conditions (also shock) oo = freestream conditions

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Shock tube instrumentation techniques developed for the study of convective heat transfer and the radiative properties of high temperature gases at conditions simulating hypervelocity entry into planetary atmospheres are described. An electrically heated helium driven shock tube is used; measurement methods suitable for conventional shock tubes must be modified before they can be used in the hypervelocity shock tube. Extremely high shock velocities necessary for proper simulation are associated with very short test times imposing requirements for fast response instrumentation systems. Methods for evaluating test gas quality are illustrated.Techniques described have been applied to several studies; typical results are shown and instrumentation requirements for the extension of aerothermodynamic investigation in the hypervelocity regime are outlined.

This chapter investigates the reasons for the deposition and non-retrieval of Viking Age silver hoards, focusing on the two areas with the biggest hoard concentrations in the Baltic zone: Gotland and Pomerania (the southern shore of the Baltic sea area in modern-day northern Germany and Poland). The chapter advances a new model for determining the possible reasons for hoard deposition and non-retrieval, arguing that hoards intended for retrieval were placed in containers, with containerless hoards likely deposited for ritual motives, without the intention of recovery. The impact on local soil chemistry on the preservation of hoard containers is considered. The evidence for containers is then integrated with analysis of the weight of hoards and local settlement archaeology. A key finding is that, on Gotland, the practice of symbolically depositing small silver hoards on ‘broken fields’ (newly established farms) was widespread.