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The Apollo command and service module sequential events control subsystem is described, with particular emphasis on the major systems and component problems and solutions. The subsystem requirements, design, and development and the test and flight history of the hardware are discussed. Recommendations to avoid similar problems on future programs are outlined.
The environmental control systems and system requirements of the Apollo command service module and the lunar module are described. The overall performance of both systems during the Apollo program is discussed. Other topics covered include: dust control, EVA provisions, Apollo 13 emergency, component redundancy, modular construction, and subatmospheric design.
A set of planning guidelines for multi-community command and control systems in law enforcement is presented. Essential characteristics and applications of these systems are outlined. Requirements analysis, system concept design, implementation planning, and performance and cost modeling are described and demonstrated with numerous examples. Program management techniques and joint powers agreements for multicommunity programs are discussed in detail. A description of a typical multi-community computer-aided dispatch system is appended.
A detailed description is presented of the simulation philosophy and process used in the development of a Separate Surface Attitude Command control system (SSAC) for a Beech Model 99 Airliner. The intent of this system is to provide complete three axes stability augmentation at low cost and without the need for system redundancy. The system, although aimed at the general aviation market, also has applications to certain military airplanes as well as to miniature submarines.
A review of the command and service module controls and displays subsystem is presented. The subsystem is described, and operational requirements, component history, problems and solutions, and conclusions and recommendations for the subsystem are included.
Communication system processes subcarrier that is modulated with sequential range codes and with command data. Loop locks in on range codes as they occur in sequence. When range code modulated with data-frequency arrives, loop switches to DEMOD to receive data.
The selection of relative velocity as the independent variable for the space shuttle first stage guidance attitude command tables was assessed to support the first stage guidance point design. The criterion for selecting the independent variable for first stage open loop guidance is to reduce or minimize performance dispersions, primarily those affecting structural loads. The products of angle of attack and angle of sideslip times dynamic pressure are used as load indicators, and minimizing their dispersions will indicate a minimum loads dispersion. Relative velocity is shown to be an acceptable steering independent variable.
A flight investigation was undertaken to assess the potential benefits afforded by a vertical-velocity command system (VVCS) for VTOL (vertical take-off and landing) aircraft. This augmentation system was conceived primarily as a means of lowering pilot workload during decelerating approaches to a hover and/or landing under category III instrument meteorological conditions. The scope of the investigation included a determination of acceptable system parameters, a visual flight evaluation, and an instrument flight evaluation which employed a 10 deg, decelerating, simulated instrument approach task. The results indicated that the VVCS, which decouples the pitch and vertical degrees of freedom, provides more accurate glide-path tracking and a lower pilot workload than does the unaugmented system.
On-orbit commandable lubrication of ball bearings accomplished by direct oil application to the moving ball surfaces was studied. Test results for the lubricant applicator portion of the system are presented in conjunction with a design approach for the reservoir and metering components.
Acoustic data are analyzed from a series of ground tests performed on an Aero Commander propeller-driven aircraft with an array of microphones flush-mounted on one side of the fuselage. The analyses were concerned with the propeller blade passage noise during static operation at several different engine speeds and included calculations of the magnitude and phase of the blade passage tones, the amplitude stability of the tones, and the spatial phase and coherence of the tones. The results indicate that the pressure field impinging on the fuselage represents primarily aerodynamic (near field) effects in the plane of the propeller at all frequencies. Forward and aft of the propeller plane aerodynamic effects still dominate the pressure field at frequencies below 200 Hz; but at higher frequencies, the pressure field is due to acoustic propagation from an equivalent center located about 0.15 to 0.30 blade diameters inboard from the propeller hub.
Operational application of the command generator (CG) was examined in detail in a simulation of a flight control system with the augmentor wing jet STOL research aircraft. The basic repertoire of single axis maneuvers and operational constraints are discussed, and the system behavior is tested on a rigorous STOL approach path and as affected by various approximations in the CG synthesis and types of disturbances found in the operational environment. The simulation results indicate that a satisfactory nonlinear system with general maneuvering capabilities throughout the flight envelope was developed which satisfies the basic design objectives while maintaining a practicable degree of simplicity.
The results of a feasibility study showed that on-orbit commandable lubrication of ball bearings can be accomplished by direct oil application to the moving ball surfaces. Test results for the lubricant applicator portion of the system are presented, in conjunction with a design approach for the reservoir and metering components.
The acoustic data from ground tests performed on an Aero Commander propeller driven aircraft are analyzed. An array of microphones flush mounted on the side of the fuselage were used to record data. The propeller blade passage noise during operations at several different taxi speeds is considered and calculations of the magnitude and phase of the blade passage tones, the amplitude stability of the tones, and the spatial phase and coherence of the tones are included. The measured results are compared to theoretical predictions for propeller noise and various evaluations which reveal important details of propeller noise characteristics are presented.
Spacecraft command and control are currently taking on the characteristics of general computer-to-computer interprocess communication. The evolution of these systems during the 1980s will give NASA a true general-purpose end-to-end data request capability for the first time. This concept is presented in outline, with consideration of many of the detailed analyses and subsystem tradeoffs being performed as part of the NEEDS (NASA End-to-End Data System) program.
Command detector unit operates over wide range of data rates and signal levels in space environment. It consists of signal conditioning, read-only memory, random-access memory, and digital processor. Entire unit fits on single multilayer printed-wiring board.
A flight research program was conducted to assess the effectiveness of manual control concepts and various cockpit displays in improving altitude (pitch, roll, and yaw) and longitudinal path control during short takeoff aircraft approaches and landings. Satisfactory flying qualities were demonstrared to minimum decision heights of 30 m (100 ft) for selected stabilization and command augmentation systems and flight director combinations. Precise landings at low touchdown sink rates were achieved with a gentle flare maneuver.
A functional description of command subsystem software modifications providing computer-controlled prepass data transfer, validation tests, and revised displays are described. The Mark 4-A implementation schedule is presented and subsystems configurations for the Mark 4-85 system summarized.
The Deep Space Communications Complex Command Subsystem will require major changes for the Mark IVA era. A description of the subsystem and its assemblies is contained in this article.