Radiative Heating Results from the Fire II Flight Experiment at a Reentry Velocity of 11.4 Kilometers Per Second

The results of the Fire 11 radiation experiments on a blunt Apollo-shaped reentry package indicated values of stagnation radiative heating rate that for the flight conditions at peak heating, are predictable by existing theory. The results of ground-facility experimentation are compared with the Fire data. Changes are suggested in the existing empirical relationships for nonequilibrium radiative heating associated with early reentry.

The radiation-limiting phenomena of truncation, collision limiting, absorption, and radiation cooling, and the coupling between the radiative and convective modes of heating are analyzed from the standpoint of the Fire experiment. The stagnation radiation data present strong evidence of the dominating influence of near- infrared atomic line contributions for conditions through the time of peak heating. Significant radiation from vacuum-ultraviolet sources was indicated from a combined analysis of the calorimeter and radiometer experiments.