Flight Instructors Training Procedures _revised AIC_x

iii. Rolling moments.
12. ENTRY
The aerodynamic moments are strong pro-spin, while the resultant of the inertial
moments are anti-spin. This gives a pro-spin characteristic.
Therefore autorotation is necessary to spin as it is the yaw and roll which gives the
pitching moment.
i. Wing drop at the stall.
ii. Autorotation.
iii. Position of flying controls (Full up elevator / Full Rudder in direction of spin).
iv. Engine considerations (Power assisted or power off).
13. IN THE SPIN
i. Position of flying controls (maintain aerodynamic inputs).
ii. Spinning characteristics of the aircraft type.
14. RECOVERY
i. Confirm throttle fully closed.
ii. Control use.
Anything which will reduce the yaw will be anti-spin. Anything which will reduce the roll
will eventually reduce the pitch and will, therefore, be anti-spin.
Yaw plus roll = nose up pitch.
The yaw moment is the most important, but not the only means available to the pilot to
aid the recovery from the spin. In most basic trainers the aerodynamic factors in a spin
are strong and so full opposite rudder, followed by the control column being moved
forward until the spin stops, will recover the aircraft from the spin, at which point the
rudders must be centralised to avoid a spin entry in the opposite direction and the
throttle closed.
This procedure means that the rudder will not be blanked off by the elevator during the
initial stages of the recovery.
iii. Effect of ailerons.
B (pitch) gyro plus roll = Anti-Spin yaw.
A (roll) gyro plus pitch = Pro-Spin yaw.
In aircraft with large B/A ratios, the application of aileron into the direction of the spin
will assist recovery.
This is because an increase in the rate of roll of the pitching gyro makes the yawing
moment out of spin, stronger. In aircraft where the B/A ratio is less than one (i.e.
greater mass distribution about the longitudinal axis than about the lateral axis), the Agyro
is strongest, and the effects described above will be reversed, A (roll) plus pitch –
Pro-Spin yaw.
15. WHAT HAPPENS DURING THE RECOVERY
If a full opposite rudder is applied, the aircraft does not stop yawing immediately.
However, as the control column is pushed forward, the C (yawing) gyro, plus the nose
down pitch will give an increased rate of roll, indicating an incipient recovery.
In addition, the outer wing recovers from the stall first, giving an additional increase in
the rate of roll.
The result is that the spin will seem to tighten up just before the recovery.
Note: Refer to the CL vs Angle of Attack graph.
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