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Mission studies have indicated that a launch vehicle pay-load capability void exists between the Saturn IB and Saturn V vehicles. The S-II and S-IVB stages of the Saturn V were investigated to determine the feasibility of utilizing them to satisfy the capability void. To obtain low earth orbital payloads in the range of 75,000-150,000 lb, it is necessary to augment the S-II stage thrust. This paper discusses the application of Minuteman first-stage or Titan III-C type 120 in. strap-onsolid rocket motors to provide the additional thrust to the intermediate vehicle comprised of the S-II and S-IVB. Included is a definition of the candidate vehicle configurations utilizing these solid motors and a definition of the stage modifications. The payload performance and control characteristics of the intermediate vehicles are summarized.

Compensation efforts directed at the stabilization and control of the Saturn S-II engine actuation system have given rise to nonlinear compensation philosophies that are also applicable to other types of hydraulic positioning servos. The analysis presented in this paper shows by theoretically and analog simulation techniques that a lag-lead form of compensation is superior to the presently popular dynamic pressure feedback (DPF) for reducing system step position errors in the presence of a large stiction/cou-lomb gimbal friction component. This result is important because nonlinear friction positioning errors are directly related to the magnitude of the resultant vehicle attitude limit cycle. An analog computer nonlinear system simulation was used to verify the analytical results discussed herein. Using the ITAE criterion, step and ramp responses of the system were compared to evaluate the DPF and laglead networks.

This paper describes the engine actuation system for the second stage (S-II) of the Saturn V vehicle. Four separate hydraulic systems provide thrust vector control for the vehicle during S-II boost by positioning the four gimbaled engines. A summary of the resulting system and component design and performance characteristics is included. Methods of controlling contaminants and controlling the temperature of the system in a cryogenic environment are also presented.