There are three
rotational hand controllers on the orbiter crew compartment flight
deck: one at the commander's station, one at the pilot's station
and one at the aft flight deck station. Each RHC controls vehicle
rotation about three axes: roll, pitch and yaw. During ascent, the
commander's and pilot's RHCs may be used to gimbal the SSMEs and
SRBs. For insertion and deorbit, the commander's and pilot's RHCs
may be used to gimbal the orbital maneuvering system engines and
to command thrusting of the reaction control system engines. On
orbit, the commander's, pilot's and aft flight station RHCs may
be used to command RCS engine thrusting. During entry, the commander's
and pilot's RHCs may be used to command RCS engine thrusting during
the early portion of entry and may be used to position the orbiter
elevons in roll and pitch axes in the latter portion of entry.
dictate that an RHC deflection produce a rotation in the same direction
as the flight crew member's line of sight. The aft flight station
RHC is used only on orbit. An aft sense -Z switch on panel A6 selects
the line-of-sight reference about the minus Z axis (overhead windows),
and the -X position selects the line-of-sight reference about the
minus X axis (aft windows) in order for aft RHC commands to be correctly
transformed to give the desired orbiter movement.
are located on the RHC. A backup flight system (BFS) mode button
on the commander's and pilot's RHCs engage the BFS when depressed.
The commander's, pilot's, and aft flight station RHCs have a two-contact
trim switch that can be pushed forward or aft to add a trim rate
to the RHC pitch command; pushing it left or right adds a roll trim
rate. The aft RHC's trim switch is inactive. The communications
switch on each RHC is a push-to-talk switch that enables voice transmission
when the switch is depressed.
Each RHC contains
nine transducers: three redundant transducers sense pitch deflection,
three sense roll deflection and three sense yaw deflection. The
transducers produce an electrical signal proportional to the deflection
of the RHC. The three transducers are called channels 1, 2 and 3;
the channel selected by redundancy management provides the command.
Each channel is powered by a separate power supply in its associated
display driver unit. Each controller is triply redundant; thus,
it takes only one good signal from a controller for the controller
Each RHC has
an initial dead band of 0.25 of a degree in all three axes. To move
the RHC beyond the dead band, an additional force is required. When
the amount of deflection reaches a certain level, called the softstop,
a step increase in the force required for further deflection occurs.
When a software detent position is exceeded, that RHC assumes control.
occurs at 19.5 degrees in the roll and pitch axes and at 9.5 to
10.5 degrees in the yaw axis. To reach the softstop in the roll
axes, 40.95 inch-pounds of static torque deflection are required;
38.2 inch-pounds are needed in pitch and 7 inch-pounds in yaw.
hardstop that can be obtained in an axis is 24.3 degrees in the
roll and pitch axis and 14.3 degrees in the yaw axis.
flows from the RHCs to the flight control system through redundancy
management and a SOP before it is passed to the aerojet digital
In a nominal
mission, the flight crew has manual control of the RHC during every
major mode except terminal countdown. When an RHC deflection exceeds
the detent in an axis, the RHC SOP generates a discrete signal that
converts the RHC from the automatic mode to control stick steering,
or hot stick. However, during ascent when the ascent digital autopilot
is active, a CSS pitch and/or roll/yaw mode push button light indicator
on panel F2 or F4 must be depressed in order for manual inputs to
be implemented into the flight control system from the commander's
or pilot's RHC. When a CSS pitch or roll/yaw push button light indicator
is depressed on panels F2 or F4, the white light for the push button
indicator will be illuminated and that axis will be downmoded from
automatic to CSS.
When the flight
crew commands three-axis motion using the RHC, the GPCs process
the RHC and motion sensor commands; and the flight control system
interprets the RHC motions (fore and aft, right and left, clockwise
and counterclockwise) as rate commands in pitch, roll and yaw and
then processes the flight control law (equations) to enhance control
response and stability. If conflicting commands are given, no commands
flight, any one of the three stations can input three-axis control
commands to the flight control system. During entry and landing,
the commander and pilot have two-axis (roll and pitch only) capability.
Roll, pitch and yaw aerosurface deflection trim is controlled by
the panel trim switches, while roll and pitch vehicle rate trim
is controlled with the trim switches on the RHC. For a return-to-launch-site
abort, both the commander's and pilot's RHC have three-axis capability
during major mode 601 and roll and pitch during major modes 602
RHC is powered when the flt cntlr (controller) on/off switch on
panel F7 is positioned to on . The pilot's RHC is powered when the
flt cntlr on/off switch on panel F8 is positioned to on. The aft
RHC is powered when the flt cntlr on/off switch on panel A6 is positioned
to on .
If a malfunction
occurs in the commander's or pilot's RHC, the red RHC caution and
warning light on panel F7 is illuminated.
The RHC contractor
is Honeywell Inc., Clearwater, Fla.