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This research program addressed the dynamics, estimation, and orbit determination of Tethered Satellite Systems (TSS). In a three year investigation we: (1) considered and reported on the state-of-the-art knowledge regarding TSS identification and motion prediction; (2) reviewed tracking, estimation, and orbit determination algorithms and models currently used by the Air Force; (3) developed algorithms for the detection, quick identification, orbit determination, and tracking of TSS: (4) developed techniques for the accurate prediction of the motions of TSS that have been detected, identified, and tracked; (5) developed-methods of detecting changes in the configuration of a TSS; and (6) use the knowledge and experience gained in (1) through (5) above to define and complete additional tasks of interest to the Air Force. Eased on the results of both simulated and real data, we have demonstrated that the three-stage orbit determination method developed and presented in this report can indeed be used for the preliminary orbit determination, quick-look identification, and long-term orbit determination and motion prediction of TSS. While the results are encouraging, additional work is clearly needed in order to verify, test, and develop these new techniques to achieve software packages which will be operationally useful.

Results are reported of an investigation into the passive control capability of launchers for free-flight rockets. Cause of free-flight rocket dispersion (principally thrust misalignment), the general concept of passive control and the potential of launchers as passive controllers are discussed. Control of important free flight rockets by altering launch conditions is treated as a preliminary step. Next, launcher conditions caused by rocket imperfections are considered. The concept of 'nonlinear frequency response' of a launcher/rocket system is used to define frequency bands which result in favorable launch conditions. Although only limited numerical results are obtained, they indicate that for a non-tip-off, light-weight (as compared to the rocket) launcher, or sub-launcher, of the type considered there are two frequency bands, one very high and one fairly low, within which the launcher is very effective as a passive controller of rocket dispersion. For a tip-off launcher, the results are similar, but operation within a low frequency band produces better control. Theoretically, dispersion can be reduced to less than fifty percent of the 'rigid launcher' value. (Author)

The results of an analysis of the effects of transverse vibration of a spinning, flexible, free-flight rocket during its guidance phase on its attitude motion subsequent to end of guidance (EOG) are presented. Two models of a spinning, flexible, free-flight rocket are described. One is a simple two-body model. The other is a 'continuous' model. A physical explanation is given for the way transverse vibration during the guidance phase causes the appearance of a transverse angular rate at EOG. The two-body model is used to obtain a simple equation from which estimates of the transverse angular rate can be found. Typical results from the two models are presented and agreement between the results is shown.

Results of an investigation concerned with evaluating factors which contribute to the mallaunch of free rockets are reported. Modifications to a previously developed digital computer code which simulates the dynamics of a single-round rocket/launcher, from the time the rocket is at rest on the launcher until it impacts, are described. These modifications make the simulation much more realistic. A new 'rigid-constraints' model for a single-round rocket/launcher system is described and vector/matrix methods are used to obtain matrix ordinary differential equations which govern the system's motion. A digital computer code which implements the numerical solution of these equations is included. Both codes (modified and new) are very general and provide for modeling the effects of launcher motions, rocket dynamic unbalance, thrust malalignment, winds, rocket aerodynamics and variable rocket inertia characteristics. The new code also provides the capability for modeling jet damping and requires less computer time than the modified code. Typical simulation results are presented. Pitch data from two free rocket test flights are compared with simulation results. It is concluded that dynamic unbalance and/or thrust malalignment affected the motions of the two rockets considered, but that other factors of uncertain origin were also presented. Recommendations for further study are made. (Author)

A concept is advanced for using the motion of launchers of a free-flight launcher/rocket system which is caused by random imperfections of the rockets launched from it to reduce the total error caused by the imperfections. This concept is called 'passive launcher control' because no feedback is generated by an active energy source after an error is sensed; only the feedback inherent in the launcher/rocket interaction is used. Relatively simple launcher models with two degrees of freedom, pitch and yaw, were used in conjunction with a more detailed, variable-mass model in a digital simulation code to obtain rocket trajectories with and without thrust misalignment and dynamic imbalance. Angular deviations of rocket velocities and linear deviations of the positions of rocket centers of mass at burnout were computed for cases in which the launcher was allowed to move ('flexible' launcher) and was constrained so that it did not rotate ('rigid' launcher) and ratios of flexible to rigid deviations were determined. Curves of these error ratios versus launcher frequency are presented. These show that a launcher which has a transverse moment of inertia about its pivot point of the same magnitude as that of the centroidal transverse moments of inertia of the rockets launched from it can be tuned to passively reduce the errors caused by rocket imperfections.