Extract from a report on the resistance of spheres of small diameter in an airstream of high velocity

A. Toussaint, Hayer
naca-tn-45
Mar 1921


Much attention is given here to the design of the wind tunnel and the experimental set-up. In comparing their results on the wind resistance of spheres to the results of other researchers, the authors find wide discrepancies. They are unable to explain the cause of the discrepancies, concluding, as they do, that the differing results could not be explained by the action of the wind tunnel walls.

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http://naca.central.cranfield.ac.uk/reports/1921/naca-tn-45.pdf