Wind Tunnel Tests of Natural Shape Balloon Model.

摘要

To further the development of high-altitude tethered balloons, wind tunnel testing of a rigid model of a natural shape balloon was performed. The rigid model tested represented a shape with top loading F/p = zero, superpressure parameter alpha = 0.9315, and Sigma = 0.0315. Aerodynamic data obtained in the 12-foot pressure tunnel include lift, drag, pitching moment, and surface pressure distribution for the Reynolds number range of 450,000 to 12 million. Examination of the data indicates that (1) stall occurs at a positive angle of attack less than 10 degrees, (2) an aerodynamic unstable trim point occurs between 5 and 15 degrees angle of attack, and (3) the drag at zero degrees angle of attack is greater than that of a sphere at the same Reynolds number. (Author)