Accession Number:

ADA164596

Title:

Factors Affecting the Vertical Motion of a Zero-Pressure, Polyethylene, Free Balloon

Descriptive Note:

Scientific interim rept. 31 Dec 1983-31 Dec 1984

Corporate Author:

AIR FORCE GEOPHYSICS LAB HANSCOM AFB MA

Personal Author(s):

Report Date:

1985-05-31

Pagination or Media Count:

104.0

Abstract:

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.

Subject Categories:

  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE