Turns

3.turns. Turns

A turn is one of the four fundamental flight maneuvers and the means by which a pilot changes the airplane's direction of flight. Although it appears simple, the turn requires the coordinated use of all three flight controls — ailerons, rudder, and elevator — together with appropriate power management. A properly executed turn is coordinated, meaning the longitudinal axis of the airplane is aligned with the curved flightpath, the inclinometer ball is centered, and the airplane is neither slipping nor skidding.

Aerodynamic Basis

An airplane turns because the horizontal component of lift pulls it around the curve, not because the rudder yaws the nose. When the airplane is banked, total lift is tilted from the vertical and resolves into two components:

• Vertical component of lift — opposes weight and holds the airplane up.
• Horizontal component of lift — acts toward the inside of the turn and provides the centripetal force that curves the flightpath.

Because the vertical component is reduced as bank increases, the pilot must add back pressure on the elevator to increase the angle of attack and restore total lift. This increases load factor (G-load), which in turn increases stall speed. Stall speed in a level turn equals Vs × √(load factor). At a 60° bank in level flight, load factor is 2 G's and stall speed increases by about 41%.

Classification by Bank Angle

Turns are typically grouped into three categories:

• Shallow turns — bank less than approximately 20°. The airplane's inherent lateral stability tends to roll it back to wings level, so the pilot must hold a small amount of aileron pressure into the turn.
• Medium turns — bank between approximately 20° and 45°. The airplane tends to remain at the established bank; ailerons can be neutralized once the desired bank is reached.
• Steep turns — bank greater than approximately 45°. The overbanking tendency causes the airplane to continue rolling into the turn, requiring opposite (out-of-turn) aileron pressure to maintain a constant bank.

Adverse Yaw and Coordinated Use of Rudder

When aileron is applied to roll into a turn, the down-going aileron on the rising wing produces more lift and more induced drag than the up-going aileron on the descending wing. This drag differential yaws the nose opposite the direction of roll — known as adverse yaw. Rudder pressure in the direction of the turn is required during roll-in (and roll-out) to overcome adverse yaw and keep the longitudinal axis aligned with the flightpath. Once the bank is established and the ailerons are neutralized, very little rudder is needed in a coordinated turn.

Slipping vs. Skidding Turns

• Slipping turn — bank is too steep for the rate of turn, or insufficient rudder is used. The ball falls toward the inside (low) wing. The airplane slides toward the inside of the turn.
• Skidding turn — too much rudder for the bank, or bank is too shallow for the rate of turn. The ball moves to the outside of the turn. A skidding turn at low altitude with back pressure is the classic setup for a cross-control stall and spin — the most dangerous condition in the traffic pattern base-to-final turn.

The correction in either case is the same: "step on the ball" to recenter it, and adjust bank as needed.

Procedure for Entering a Level Turn

1. Clear the area with clearing turns or a thorough visual scan in the direction of the turn.
2. Pick a reference point on the horizon to judge bank attitude.
3. Smoothly and simultaneously apply coordinated aileron and rudder in the direction of the turn.
4. As the bank passes about 15°–20°, add slight back pressure on the elevator to maintain altitude.
5. Add a small amount of power if needed (typically required for bank angles greater than ~30°) to overcome the induced drag and maintain airspeed.
6. Neutralize aileron and rudder once the desired bank is established (in medium turns); apply slight opposite aileron in steep turns to prevent overbanking.

Recovery from a Turn

Lead the rollout by approximately one-half the bank angle in degrees (e.g., begin rollout from a 30° bank about 15° before the desired heading). Apply coordinated aileron and rudder away from the turn, simultaneously releasing the back pressure and reducing any added power as the wings approach level.

Common Errors

• Failure to clear the area before turning.
• Uncoordinated entry — too much or too little rudder, ball not centered.
• Gaining or losing altitude due to incorrect elevator back pressure.
• Fixating on the nose rather than dividing attention between outside references and the instruments.
• Allowing bank to vary because of failure to compensate for overbanking or underbanking tendencies.