NASA Office of Logic Design

NASA Office of Logic Design

A scientific study of the problems of digital engineering for space flight systems,
with a view to their practical solution.

NASA SP-504: Space Shuttle Avionics System

Section 3  Display and Control

The major challenge facing the designers of the Space Shuttle cockpit was to integrate all the controls and displays required for operation of the vehicle and its subsystems into the space available, within the reach and vision of the crew as appropriate for each mission phase. Some of the basic requirements imposed were

In addition, the system would have to provide for both space flight and aircraft aerodynamic flight, a first in the manned space program. In the early design phases, the controls required for these two flight modes were thought to be so incompatible that consideration was given to incorporating two separate cockpits, one exclusively devoted to and equipped for aerodynamic flight, the other for space operations. The program could not afford the cost, complexity, and inefficiency of such an approach, however, and a single, integrated, two-man forward control station was baselined for both regimes. The aft portion of the upper cockpit, because of visibility advantages looking up, aft, and into the payload bay area, was equipped with controls and displays sufficient for on-orbit proximity and payload operations. Despite the integrated approach, however, dedication of some devices to one or the other flight regime could not be avoided. The preferred pilot input devices for aerodynamic flight were a traditional control stick (or yoke/wheel) and rudder pedals. For space flight, three-axis hand controllers for attitude and translation control were desired. After much deliberation and many simulations, the decision was made to adopt a variation of a side-arm controller which would provide pitch and roll input capability in the aircraft mode and pitch, roll, and yaw inputs in the spacecraft mode. These devices were located in the standard aircraft position between the pilot's and copilot's legs, situated to provide clearance for ejection, a capability included on early flights. Rudder/brake pedals, active only in the aerodynamic mode, were included to provide yaw inputs and to apply the wheel brakes. Other devices dedicated to aerodynamic flight included the speed brake and body flap controls. A three-axis translation controller was included to provide on-orbit maneuver capability. Most displays served a dual or universal purpose; however, some, such as air data, the radar altimeter, and those associated with navigation aids, became active only after blackout. The display and control concepts proposed very early in the program included extensive use of multifunction CRT's, reformattable control panels, multipurpose keyboards, head-up displays, and limited use of dedicated switches and circuit breakers. The technology involved was then at the leading edge of the state of the art for aerospace systems, however, and, because it appeared that more conventional approaches would suffice, the decision was made to use off-the-shelf equipment wherever possible. The system which evolved, therefore, contains an extremely large number and variety of components. Control devices include toggle, pushbutton, thumbwheel, and rotary switches; potentiometers; keyboards; circuit breakers; and hand controllers. Displays include circular and vertical meters, tape meters, mechanical talkbacks, annunciators, flight control meters, electromechanical position and attitude indicators, digital readouts, and CRT's. The four CRT's in the final design incorporate multifunctionality but to a much smaller degree than those in the original concepts.

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