Self-Induced Balloon Motions

Harold N. Murrow NASA Langley Research Center, Hampton, Va.

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Robert M. Henry NASA Langley Research Center, Hampton, Va.

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Abstract

Rigid spherical balloons were released in still air to assess magnitudes of possible self-induced motion. They were found to exhibit oscillations similar to those previously reported for rubber balloons. These oscillations are not simple sinusoidal motion, and are not limited to a single plane. The root-mean-square horizontal velocity is proportional to the vertical terminal velocity, and for the ROSE sphere appears to he one-half the terminal velocity. Slight roughening (roughness ratio = 0.0016) had no apparent effect. Greater roughness (roughness ratio = 0.03) appears to reduce the amplitude and predominant wavelength of the oscillation.

Abstract

Rigid spherical balloons were released in still air to assess magnitudes of possible self-induced motion. They were found to exhibit oscillations similar to those previously reported for rubber balloons. These oscillations are not simple sinusoidal motion, and are not limited to a single plane. The root-mean-square horizontal velocity is proportional to the vertical terminal velocity, and for the ROSE sphere appears to he one-half the terminal velocity. Slight roughening (roughness ratio = 0.0016) had no apparent effect. Greater roughness (roughness ratio = 0.03) appears to reduce the amplitude and predominant wavelength of the oscillation.

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