Figure 1-8 Turn Needle

T-34C OUT-OF-CONTROL FLIGHT

CHAPTER ONE

The turn needle is the only reliable indicator of spin direction.

Figure 1-8 shows the needle pegged in the direction of rotation and the balance ball simply

oscillating around the center position, which is typical for the T-34C in an erect spin.

Figure 1-8 Turn Needle

Generally speaking, ailerons are not very effective in light aircraft at stalled AOA and should not

be used for entry or recovery. In fact, application of ailerons creates a yawing motion in the

opposite direction, known as adverse yaw. At spin initiation, a cross control situation enhances

spin entry. Conversely, deflection of ailerons into the spin reduces the autorotation rolling

moment by reducing the AOA on the "inside" wing and can produce the adverse yaw necessary

to aid rudder yawing moments to effect recovery. Figure 1-9 diagrams the forces, which occur

during the spin that cause the aircraft to autorotate.

1-6 INTRODUCTIONS AND SPINS