position indicator is a single display on panel F7 that is active
during entry and during the entry portion of RTLS. The SPI displays
the actual and commanded positions of the elevons, body flap, rudder,
aileron and speed brake.
The four elevon
position indicators show the elevon positions in the order of appearance
as viewed from behind the vehicle (from left to right: left outboard,
left inboard, right inboard, right outboard). The scales all range
from plus 20 to minus 35 degrees, which are also the software limits
to the elevon commands. The pointers are driven by four separate
signals and can read different values, but normally the left pair
is identical and the right pair is identical. Positive elevon is
below the null line and negative is above.
The body flap
scale reads body flap positions from zero to 100 percent of software-allowed
travel. Zero percent corresponds to full up (minus 11.7 degrees);
100 percent corresponds to full down (plus 22.5 degrees). The small
pointer at 35 percent is fixed and shows the trail position.
is displayed as if viewed from the rear of the vehicle. Deflection
to the left of center represents left rudder. The scale is plus
30 degrees (left) to minus 30 degrees (right), but software limits
the rudder command to plus or minus 27.1 degrees.
display measures the effective aileron function of the elevons in
combination. Aileron position equals the average of the left and
right elevon divided by two. Deflection of the pointer to the right
of center indicates a roll-right configuration (left elevons down,
right elevons up) and vice versa. The scale is minus 5 to plus 5
degrees, with minus 5 at the left side. The aileron command can
exceed plus or minus 5 degrees (maximum plus or minus 10 degrees),
in which case the meter saturates at plus or minus 5 degrees.
The speed brake
position indicator indicates the actual position on the upper scale
and commanded position on the lower scale. The position ranges zero
to 100 percent; zero percent is fully closed and 100 percent is
fully open, which corresponds to 98 degrees with respect to the
hinge lines. The small point at 25 percent is fixed and represents
the point at which the speed brake surfaces and the remainder of
the tail form a smooth wedge.
The speed brake
command is scaled identically to position and has the same travel
limits. It always represents the speed brake auto guidance command.
The off flag is set only for internal meter problems or during OPS
8 display checkout.