the C-hook pickup axis to move laterally from a vertical path will be met with a centering reaction at the Chook pickup axis (see Figure 9). This reaction is the horizontal component of the tension in the cable and increases as the cable angle deviates from vertical. This centering effect also increases as the HGAS deploys as cable length shortens and angle increases. For a deviation of 76 mm (3 in), the horizontal centering force would be on the order of 10 N (3 lb) for the fully deployed system. If HGAS deploys along its designed path this force is negligible. Another subtlety discovered was  the effect of cable length/mass switching sides of the g-negation cable/pulley system. As the  system deployed, cable length on  C-hook end of the cable/pulley system would shorten, while cable length on the C-hook counter  mass end of the system would  lengthen by an equal amount. The C-hook pickup axis moves vertically 1.9 m (75 in) during deployment. This effectively increased the counter mass on the C-hook counter mass side of  the cable and thus decreased the  amount of stow bias from the g-negation system by approximately  0.75 kg (1.65 lb) at the end of  deployment. This feature was  corrected by the addition of a length of chain (with the same linear density as the cable) to the C-hook  counter mass. The chain was hung from the C-hook counter mass to a collection pan on the floor. As the  length of cable shortened on the C-hook side of the cable/pulley system, the same length of chain piled  up in the collection pan on the floor, balancing the effect.   Baseline (Flight-like) Dynamic Model During the course of GPM HGAS manufacture and integration, a dynamic HGAS computer model was  developed using MSC ADAMS to aid in predicting on-orbit deployment path and deployment time. Later,  the model was enhanced by adding ground deployment GSE to simulate g-negated ground deployments. The ADAMS model was very much a “living document”. It was first built with nominal values for spring  torques, dampers, masses, etc. The model was continually updated as more accurate information of various flight components became available. Eventually, the model migrated towards representing the flight configuration in high fidelity with the exception of certain unknowns such as hinge friction coefficients and in-situ harness torques. Key features of the model are detailed below: /g120/g43/g76/g81/g74/g72/g3/g39/g72/g83/g79/g82/g92/g80/g72/g81/g87/g3/g54/g83/g85/g76/g81/g74/g3/g55/g82/g85/g84/g88/g72/g29 The deployment spring torque at both hinges used the torque vs.  angle data gathered for the serialized flight springs during sub-component testing. While the springs  were intended to be constant torque springs, the torque isn’t truly constant and varies as a function of angle. /g120/g57/g68/g85/g76/g68/g69/g79/g72/g3/g39/g68/g80/g83/g76/g81/g74/g3/g38/g82/g72/g73/g73/g76/g70/g76/g72/g81/g87/g86/g29 The fluid hinge dampers have damping coefficients that are a function  of angular velocity and temperature. In addition, the damping varies unit to unit. Damping  performance at various temperatures and angular velocities was measured in the serialized flight units. Damping coefficient vs. angular velocity curves, at various temperatures, were generated based on that test data and incorporated into the ADAMS model.  /g3 Figure 5. Deployment Data for HGAS Qualification   50