This paper critiques existing aerodynamic-thermodynamic models for predicting the vertical motion of free balloon systems. It demonstrates that: a) the aerodynamic drag coefficient model should be based on Froude number and fractional volume as well as Reynolds number; b) there has been a widespread error in definition of the instantaneous mass of the balloon film involved in the heat transfer process; c) the gas bubble cannot be modelled as a sphere; d) the gas bubble is asymmetrical except when near or at its natural ceiling altitude; and e) the actual gas bubble shape, and most probably the added mass, is directly related to the type of gore pattern. Finally, a procedure is proposed for the analysis of actual flight data to enable the development of a practical, but also theoretically sound, model of the aerodynamic drag coefficient of a zero-pressure, free balloon- and subsequent refinement of the heat transfer models for direct and reflected solar energy.

Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

The thirty-eight papers presented in this volume comprise a selection of those given at the symposium on Scientific Ballooning. The papers have been divided into five sections dealing with balloon design and new balloon materials, balloon programmes and long duration flights, balloons on other planets, instrumentation for balloons and recent scientific observations.