I guess that's also why the horizontal stab folds down in a hover, huh?! So you don't push your own tail down?
(that IS a serious question)
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The stabilator is a variable angle of incidence airfoil that enhances the handling
qualities and longitudinal control of the aircraft. The automatic mode of operation
positions the stabilator to the best angle of attack for existing flight conditions.
The stabilator is programmed to its optimum angle to provide the following functions:
S 1. Streamline with main rotor downwash at low airspeed (30 KIAS and below)
to minimize nose-up attitudes resulting from the main rotor downwash on the stabilator.
(Airspeed/air data transducer)
C 2. Provide Collective coupling to minimize pitch attitude excursions due to
collective inputs. An increase in the collective would result in the helicopter pitching up.
The stabilator will program trailing edge down to prevent the nose from pitching up. As
collective is reduced the stabilator will program trailing edge up to prevent the nose
from pitching down. (Collective position transducer)
A 3. Decrease Angle of incidence (program up) as airspeed increases to
enhance static and longitudinal stability. (Airspeed/air data transducer)
L 4. Lateral Sideslip to Pitch Coupling to reduce susceptibility to gusts. Also
compensates for downwash on the stabilator and tail rotor efficiency. In forward flight,
the downwash on the retreating side is weaker than the downwash on the advancing
side. If a right sideslip is entered (left pedal applied), the stabilator encounters
increased downwash and the nose tends to pitch up, therefore the stabilator programs
down to prevent the nose up attitude. A right sideslip condition also results in increased
induced flow through the tail rotor and a corresponding decrease in the amount of lift
provided by the tail rotor. In a left sideslip (right pedal applied), the stabilator is
positioned in a reduced downwash condition and the nose tends to pitch down. The
stabilator programs trailing edge up to prevent the nose from pitching down. A left
sideslip condition also results in decreased induced flow through the tail rotor and a
corresponding increase in the amount of lift provided by the tail rotor. (Lateral
Accelerometers)
P 5. Provide Pitch rate feedback to improve longitudinal stability and to reduce
susceptibility to wind gusts. Pitch rate is sensed by pitch rate gyros in each stabilator
amplifier and corrections are made to help maintain level pitch attitudes during turbulent
conditions. The stabilator also programs as G loading increases in turns. G forces
acting upon the fuselage tend to pull the nose down in a turn, and the stabilator
programs trailing up to prevent the nose from dropping. (Pitch rate gyros)
I hope that makes it clear as mud as to what the stabilator on the UH-60 actually does.