Abstract
The course of development of Army radio equipment at the Signal Corps Engineering Laboratories for the measurement of upper wind velocities is reviewed. It is indicated that this type of information is needed for the successful navigation of aircraft, for weather predictions, and for the determination of ballistic winds used in connection with artillery fire. Operation of the two latest types of direction-finders, for upper wind measurements up to 100,OO~O feet altitude, is described in some detail. Performance data are given. Sources of error in connection with accuracy measurements are discussed quantitatively. ,Standard angular errors of the apparatus considered are in the range from 0.05 to 0.15 degrees.
