Electrical engineering: Gyroscopic stabilizer for tank guns

IN 1939 the problem of stabilizing guns in tanks for the condition of traveling over rough terrain was presented by Colonel David J. Crawford, Ordnance Department, United States Army, then a captain at Aberdeen Proving Ground. Colonel Crawford had previously seen certain regulating devices involving the use of gyroscopes and felt that such a combination of equipment would be necessary in the solution of his problem. Consideration was given to this, and it was found that the required speeds and accelerations of the power drive for such a stabilizer were in excess of anything previously attempted. For example, the principal disturbances were at about 1 1/2 cycles per second corresponding to the pitching frequency of the tank on its springs, and displacements were such as to cause rates of about 30 degrees per second and accelerations of 300 degrees per second per second.