Estimates of Flight Regimes in the Venus Atmosphere

A study of the aerodynamic flight regions that may be encountered during entry into the atmosphere of Venus, and an estimate of the gross aerodynamic behavior of objects entering that atmosphere. It is found that the best evidence available does not permit an estimate of a single likely model atmosphere suitable for aerodynamic use. Substantial differences in flight regions, particularly in the troposphere, must be considered. Depending on the models used, the continuum flight region is entered at altitudes between about 150 and 80 km above the visible cloud layer. In view of this uncertainty in the structure of the Venus atmosphere, a more detailed analysis of flow problems in shock layers, boundary layers, etc., would be premature. The flight regime limits given, however, may provide design criteria for probes approaching the planet or possibly those reaching the cloud layer itself.