T-45C TS & ADV CO-09; IUT CO-05
Velocity Vector
LESSON NOTES
When the velocity vector is limited due to a high
positive (or low negative) AOA, the HUD pitch ladder
will rotate, as required, to accurately display the True
velocity vector's position on the pitch ladder.
Consider the following example: Pitch angle is zero;
aircraft nose is on the horizon. True AOA is +25
degrees; the HUD digital readout is approximately 33
(units). The velocity vector is at the bottom of the
HUD and is flashing to indicate it is limited.
The pitch ladder is rotated in order to show the velocity
vector at minus 25 degrees descent angle, which
correlates with True AOA (+25 degrees) and zero pitch
attitude. Pitch ladder rotation is necessary to display
True AOA at minus 25 degrees, since the 11.13 degree
HUD vertical display limit is exceeded. That causes
the climb/dive waterline pitch reading to become
invalid. Instead of it indicating zero pitch attitude (the
aircraft's actual pitch), the HUD waterline reference
now indicates the aircraft nose to be pitched down 14
degrees, which is an incorrect pitch representation.
Fourteen (14) degrees represents the amount of
rotation required to display the limited velocity vector
at its 25 degrees nose down position in the HUD field-
of-view.
d.
The velocity vector can also become
Sg 3, fr 5
laterally limited
LATERALLY LIMITED VELOCITY
VECTOR -- NO PITCH LADDER
ROTATION
Page 9-8
(10-99) Original
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