Space Shuttle Avionics: Difference between revisions

=== ASCENT TRAJ 1 (OPS 101 and 102) ===

This screen is almost as accurate as the original. It shows the vertical situation during the ascent - the central section is a plot of altitude vs. relative speed and the line is the planned ascent trajectory. If the Shuttle symbol moves above the line, it means the climbing angle is too steep and the spacecraft is too high for its velocity, if it falls below it means the ascent is too shallow. A predictor circle shows the anticipated state of the spacecraft 20 seconds in the future assuming no changes in attitude or throttle occur. This allows to plan the ascent path when flying manually.

=== ASCENT TRAJ 2 (OPS 103) ===

This screen becomes visible during the second part of the ascent (after SRB separation). It is an accurate version of the original (PASS and BFS) and shows the same vertical situation as the previous screen, but at different scales. In addition, it offers information in throttle setting and remaining propellant. The inertial speed scale is magnified from 25.000 to 26.000 ft/s in the upper part of the screen and shows the anticipated point of main engine cutoff (marked by CO).

=== MNVR (OPS 104, 105, 202, 301, 302, 303) ===

With this screen, orbital maneuvering is controlled. Changes to the current orbit can be entered as so called Powered Explicit Guidance (PEG) targets, and when the target is loaded, the guidance computes automatically burn attitude, duration and the resulting changes to apoapsis and periapsis. The Shuttle can then be instructed to maneuver automatically into burn attitude and fires the OMS engines when the EXEC key on the pad is pressed as soon as attitude is reached and an EXEC symbol is flashing.

=== UNIV PTG (OPS 201) ===

Using the maneuver screen, the attitude of the Shuttle can be automatically controlled. Various options are available, ranging from specifying an inertial yaw/pitch/roll to selecting a body axis and pointing this body axis automatically towards a target (the Sun, Earth, a location on Earth,...).

=== ENTRY TRAJ 1 (2,3,4,5) (OPS 304) ===

During entry, the ENTRY TRAJ display series is used to control the deceleration for successful range management to arrive at the desired TAEM interface. The series consists of five displays, all of them showing range to go on the x-axis vs. inertial speed on the y-axis - if the Shuttle symbol is above the desired trajectory, it is too fast and needs to establish a higher sinkrate (higher bank angle) to decelerate more, if it is below the sinkrate needs to be reduced. In addition, the display also shows Delta Azimuth for planning roll reversals and the current values of deceleration and dynamic pressure qbar. To display a meaningful range, a landing site needs to be selected and entry guidance needs to be active, otherwise the avionics does not know where the Shuttle is aimed.

=== RTLS TRAJ 2 (OPS 601) ===

For the powered stage of an RTLS abort, this display provides a set of sample trajectories to guide maneuvering. It is a representation of horizontal velocity component against altitude with a zero line in the center, i.e. at the left end of the display, the Shuttle is flying back to the launch site.

=== GPC MEMORY (SPEC 0) ===

The GPC memory display is the base layer of the Shuttle software - it is what is available after a GPC has been moded to RUN. Consequently it is used to determine what application software the GPC should load.

=== TIME (SPEC 2) ===

The time utility display is responsible for how time is displayed in the generic DPS display mask. It allows to switch between GMT and MET (mission elapsed time), to define a CRT timer which can count independently of the global timer, to set three alarms (two on MET, one on CRT time) and to arrange for a count-down of time to a specific MET in the upper third.

=== GPC/BUS STATUS (DISP 6) ===

The GPC and bus status utility display contains an overview over the software configuration currently running. For each of the five GPCs, the current status (run, standby or halt) is shown along with the application software loaded (G for GNC, S for systems management, the number represents the OPS sequence.

=== DAP CONFIG (SPEC 20) ===

Using the DAP configuration, the maneuvering characteristics of the Shuttle in orbit can be customized. Both DAP-A and DAP-B can be accessed, as well as pre-loaded alternative configurations for both can be retrieved from memory or edited (the latter is not implemented in FG).  

In addition, various other options allow to (de-)select forward or aft thruster pods or to ask for compensation for mode-mixing when maneuvering.

=== S TRK/COAS CNTL (SPEC 22) ===

On the star tracker / COAS control display, two of the attitude sensors of the Shuttle can be operated.  

=== RCS (SPEC 23) ===

The RCS display page is used to monitor and manage the state of the RCS thrusters as well as (in a limited way) the propellant flow. For each individual thruster, its current state (i.e. whether it is operating normally, failed leaking, failed OFF i.e. refuses to ignite or failed ON i.e. refused a shutdown command), whether it is selected to be used and its priority in the jet table is shown.

=== RM ORBIT (SPEC 25) ===

The orbit redundancy management display is used to check (and if necessary) deselect the transducers of the various control sticks - the two forward and one aft rotational hand controller (RHC) and the forward and aft translational hand controller (THC). Whenever a controller is moved, it shows the signal picked up by the transducers.