The Gyrosyn compass

Arthur Wahl (lieutenant, United States Army Air Corps, Wright Field, Dayton, Ohio): The primary purpose of the Gyrosyn compass described in this paper is to obtain a stable and accurate indication of azimuth under a wide range of flying conditions and to have this indication as free as possible from the deviations and fluctuations inherent in the direct-reading magnetic card-type of compass. The method of arriving at such an indication by using the earth inductor (called flux valve in this paper) to sense direction with respect to the earth's magnetic field at present can be divided into two classes: Either the earth inductor is allowed to swing pendulously and is made to slave a horizontal axis gyroscope used as the indicator; or the earth inductor itself is stabilized in the horizontal plane by a vertical axis gyroscope, and its signal of direction is amplified through a servo system to give the desired indication. The first of these two, which is employed in the Gyrosyn compass, has been dealt with ably in this paper. The second, which is employed in the Gyro Flux Gate compass built by Eclipse-Pioneer division of Bendix Aviation Corporation, will be described briefly in principle of operation with a short comparison of the two systems.