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Flutter in propeller blades

Description: This report considers two different explanations for propeller breaks caused by propeller flutter. The two possibilities are combined vibrations of the blade, similar to those of the wings, which develop by absorbing energy from the air stream and converting it into vibrations without the aid of any periodic external disturbance. The other possibility examined is forced vibrations, which are produced in every structure by periodically variable impulses. Such vibrations are especially dangerous when the disturbing impulses which cause them have a frequency equal to the natural frequency of the system.
Date: October 1, 1931
Creator: Seewald, Friedrich
Partner: UNT Libraries Government Documents Department

On floats and float tests

Description: The principal source of information on float resistance is the model test. In view of the insuperable difficulties opposing any attempt at theoretical treatment of the resistance problem, particularly at attitudes which tend toward satisfactory take-off, such as the transitory stage to planing, the towing test is and will remain the primary method for some time.
Date: September 1, 1931
Creator: Seewald, Friedrich
Partner: UNT Libraries Government Documents Department

Determination of Stresses and Deformations of Aircraft Propellers

Description: A method is described for testing the strength of propellers of any shape. It is shown that the shape of the propeller greatly affects the stresses, and that great caution must be exercised if the relieving effect of the centrifugal force, which exists in every propeller with a straight blade axis, is to be increased by curving the blade axis. In a numerical example, the calculation is made for a certain revolution speed at which the actual distortion is then measured. The results of the calculation agree satisfactorily with the experimental results.
Date: May 1932
Creator: Seewald, Friedrich
Partner: UNT Libraries Government Documents Department

The Small Wind Tunnel of the DVL

Description: A general description of the small DVL wind tunnel is provided, with emphasis on air conduction, blower and velocity regulation, velocity measurement, and balance and model suspension.
Date: January 1934
Creator: Seewald, Friedrich
Partner: UNT Libraries Government Documents Department