means to meet such multiple requirements as simplicity, reliability, mobility, jamming  resistance, and availability of components. Work assigned to this system involved constraining the system along a ballistic trajectory from liftoff to  impact, and the principal component that performed this function was the gyro-stabilized platform (ST-90). Important to and located on the ST-90 were three air-bearing supported accelerometers that measured acceleration on the missile in three directions. Primarily, these were needed to detect and act on external forces that might Influence the trajectory. To some extent, certain forces such as standard thrust of the propulsion system, aerodynamic drag, and separation forces could be determined before firing, and, if the missile had only these to contend with, the trajectory would be standard and the G&C problem simple. But non- standard forces, which were quite unpredictable from either points in time or space, did exist and some means had to be available to start a proper reaction. Examples of the non-standard type include wind gusts and deviations in thrust. Thus, the problem at hand, when occasioned by these external forces, was to bring the missile from its actual trajectory to that desired in order to assure a CPE of not greater than 1,500 meters. Since guidance was not feasible during the re-entry phase, these problems had to be solved before nose cone separation 70 . There were also several other major components that made up a part of the G&C system. One of these was the guidance computer, which was packaged  outside the ST-90 because of weight. This unit received its input from a gyro accelerometer, and was concerned with distance and speed information. A  programming device was responsible for tilting the missile in pitch and compensating for environmental conditions      _____________________________

70. Haeussermann, Dr. Walter, the JUP All-Inertial G&C Scheme, 5 Dec 56, Hist Off files.