The electrodynamometric balance of the small wind tunnel of the French Service of Aeronautical Research
This investigation shows the attempt to improve the electrodynamomoter designed by Mr. Villey. The force to be measured acts on a flexible steel plate which is placed in front of a fixed plate. The deformation varies the original thickness of the layer of air between the two plates, thus causing a more rapid variation in the coefficient of electrostatic attraction of the two plates than in the capacity of the condenser formed by the dynamometer. The measurements are made by a differential method. The capacity of the test dynamometer is compared with that of a similar instrument of constant capacity, this comparison being made by means of an electrometer. Diagrams are shown of the dynamometer, the electrometer, and the electrical connections.