Conservation of angular momentum plays a significant role in determining how an airplane will spin.
-Depending on wing shape and the aerodynamic properties of a wing, ailerons applied in the direction of spin will cause increased roll and yaw oscillations, while ailerons applied in the direction opposite of spin rotation will tend to dampen roll and yaw oscillations.
-The rudder is the principal control for stopping autorotation in the T-6B. During normal operation a rudder increases the angle of attack on the vertical stabilizer and produces lift, in the horizontal direction, that creates a yawing moment about the center of gravity. Due to the direction of the relative wind in a spin, the vertical stabilizer acts as a flat plate, instead of as an airfoil and the rudder is used to create drag, not lift, to create the yawing moment. The direction of the rudder has a significant effect on the amount of drag created.
-In a stabilized spin, the horizontal stabilizer and elevator are fully stalled due to an angle of attack in excess of 50°. This results in very little lift and a great amount of drag. The drag will be maximized with full down elevator and minimized with full up elevator. The increased drag on the horizontal stabilizer and elevator will cause a more nose- down pitch attitude. Similar to the vertical stabilizer, this drag will also have a vertical and horizontal component.
-A heavier airplane will have a slower spin entry with lesser oscillations due to this large moment of inertia. A lighter airplane will enter a spin more quickly, with greater oscillations possible, but will also recover from a spin faster.
-The pitch attitude will have a direct impact on the speed the aircraft stalls. For a given power setting, stall speed varies inversely with pitch attitude. As an airplane increase its pitch attitude, a larger portion of the thrust vector is in the vertical, in effect, adding lift. This additional lift reduces the load seen by the wings allowing for a slower stall speed. Slower stall speeds make the spin entry slower and with lesser oscillations. At lower pitch attitudes, the aircraft stalls at a higher airspeed and entries are faster and more oscillatory.
-Gyroscopic precession is a phenomenon that occurs when a gyroscope experiences a force. A gyroscopic mass reacts to a disturbance (force) along the rotational axis at a point 90° further in the rotation cycle. The propeller of the T-6B is a clockwise rotating gyroscope (as viewed from cockpit). If an airplane is in a right spin (nose yawing right), the nose of the T-6B will tend to pitch down due to gyroscopic precession. Conversely, if the T-6B is in a left spin, the nose will tend to pitch up. The T-6B will therefore have a flatter attitude when spinning to the left than to the right.
The strength of a vortex depends on three main factors: airplane weight, airplane speed, and wing shape.
-To maintain level flight, a heavier airplane must produce more lift, and will therefore have a greater pressure differential at the wingtip where the vortex is created. Weight is the most significant factor in the strength of wingtip vortices.
-Vortex strength has a direct correlation to induced drag, the greater the induced drag the stronger the vortex. Since induced drag is dominant at lower airspeeds, a slower aircraft will have stronger vortices. Also, a faster aircraft will spread the vortices energy over a greater distance, reducing the effect of the vortex.
-Configuration also plays a significant role in vortex strength. If the flaps are lowered, more lift is created at the wing root, which decreases the pressure differential at the wingtip. The greatest vortex strength occurs when the generating airplane is heavy, slow, and clean.
-Use the longest suitable runway. Consider crosswind, obstacles, runway surface conditions, selecting the runway.
-Use takeoff flaps, but delay rotation (VROT) by the amount of predicted wind shear (up to 10 knots). Notice, this addition applies to increasing performance wind shear.
-Rotate to normal climb attitude at increased VROT and maintain attitude.
-If wind shear is encountered near VROT, abort if possible.
-Set flaps to takeoff and increase approach speed by the amount of wind shear potential (up to 10 knots above normal). Again, notice this addition applies to increasing performance wind shear. By setting the flaps to takeoff, there will be less drag and the aircraft will be able to accelerate more quickly.
-Establish the proper approach pitch, trim, and power settings by 1000 AGL. Resist the temptation to make large power reductions. Keep in mind that increased landing speed means longer landing distances.