| Avionics
- Overview
- Controls,
or assists in controlling, most of the shuttle systems.
- Data
Processing System
- The vehicle
relies on computerized control and monitoring for successful performance.
- Software
- DPS
software is divided into two major groups: system software
and applications software.
- General-Purpose
Computers
- Five
identical computers aboard the orbiter control vehicle systems.
- Mass
Memory Units
- Computing
functions for all mission phases requires about 400,000 words
of computer memory.
- Multifunction
CRT Display System
- Displays
on the flight deck allow onboard monitoring of systems, software
processing and manual control for crew data and software manipulation.
- Master
Timing Unit
- The
GPC complex requires an accurate time source because its software
uses GMT to schedule processing.
- Computer
Data Bus Network
- Network
is divided into specific groups that perform specific functions.
- Multiplexers/Demultiplexers
- DPS
MDMs convert and format serial digital GPC commands into separate
commands for various vehicle system hardware.
- Master
Events Controllers
- Send
signalls to arm and safe pyrotechnics during SRB/ET separation.
- Data
Bus Isolation Amplifiers
- Interfacing
devices for the GSE/LPS and SRB MDMs.
- Backup
Flight Control
- The
fifth GPC, loaded with different software, provides backup
in case primary GPCs fail.
- Guidance,
Navigation and Control
- GNC software
commands effect vehicle control and provide sensor data needed
to compute these commands.
- Flight
Control System Hardware
- Hard-wired
to one of eight flight-critical MDMs.
- Navigational
Aids
- Include
IMUS, tacan units, air data probe assemblies, and more.
- Inertial
Measurement Units
- Consist
of an all-attitude, four-gimbal, inertially stabilized platform.
- Star
Trackers
- Two
star tracker units are part of the navigation system.
- Crewman
Optical Alignment Sight
- Used
if IMU alignment is in error more than 1.4 degrees.
- TACAN
- Determine
slant range and magnetic bearing to ground station.
- Air
Data System
- Provides
information on the movement of the orbiter in the air mass.
- Microwave
Scan Beam Landing System
- Used
during landing phase to determine slant range, azimuth and
elevation to landing runway.
- Radar
Altimeter
- Measure
absolute altitude from the orbiter to nearest terrain within
beamwidth of orbiter's antennas.
- Accelerometer
Assemblies
- Sense
vehicle acceleration along lateral and vertical axes.
- Orbiter
Rate Gyro Assemblies
- Used
by flight control system to sense roll, pitch and yaw rates
during ascent and entry.
- Solid
Rocket Booster Rate Gyro Assemblies
- Used
as feedback to find rate errors from liftoff to SRB separation.
- Rotational
Hand Controller
- Used
by flight crew to gimbal engines and OMS/RCS systems.
- Translational
Hand Controller
- Used
for manual control of translation along the longitudinal,
lateral, and vertical axes to control RCS.
- Control
Stick Steering Push Button Light Indicators
- Indicate
control stick mode.
- Rudder
Pedals
- Command
orbiter rotation about the yaw axis by positioning the rudder
during atmospheric flight.
- Speed
Brake/Thrust Controller
- Used
during ascent to vary thrust level of main engines; used during
entry to control aerodynamic drag.
- Body
Flap Switches
- Provide
manual control for positioning body flap during entry.
- RHC/Panel
Enable/Inhibit
- Provide
signals to GPCs, prohibiting execution of related software
commands while RHC is active.
- Trim
Switches
- Used
to move the aerosurfaces in roll, pitch and yaw.
- Aerosurface
Servoamplifiers
- Receive
commands during atmospheric flight, causing aerosurface deflections.
- Digital
Autopilot
- Composed
of several software modules that interpret maneuver commands
and generate commands for the appropriate effectors.
- Rendezvous
Thrusting Maneuvers
- OMS/RCS
thrusting periods can be used to correct or modify the orbit
as required.
- Component
Locations
- Black
boxes are situated in several locations around the orbiter.
- Dedicated
Display Systems
- Provide
the flight crew with data required to fly the vehicle manually
or to monitor automatic FCS performance.
- Attitude
Director Indicator
- Provide
attitude data, including attitude rates and errors.
- Horizontal
Situation Indicator
- Displays
a pictorial view of the vehicle's position.
- Alpha
Mach Indicator
- Display
vehicle angle of attack.
- Altitude/Vertical
Velocity Indicator
- Display
vertical acceleration, vertical velocity, barometric altitude
and radar altitude.
- Surface
Position Indicator
- Displays
actual and commanded positions of elevons, body flap, rudder,
aileron and speed brake.
- Flight
Control System Push Button Indicators
- Transmit
moding requests to digital autopilot.
- RCS
Command Lights
- Indicate
RCS jet comands by axis and direction.
- G-Meter
- Senses linear
acceleration along the Z axis of the vehicle.
- Head-up
Display
- Optical
miniprocessor that cues the commander during final landing approach.
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