Airplane Turns

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Although somewhat different from a car, steering an airplane is really not very difficult. An aircraft turns because of a change in the direction of lift—a change from completely vertical lift to lift at a horizontal angle relative to the horizon. This change is implemented when the ailerons are manipulated to place the airplane in a banked attitude—aiming the wings lift in the direction of the desired turn. It is the bank that causes the turn—not the ailerons themselves. As long as the airplane remains in a banked attitude, the turn will continue.

A properly coordinated level turn begins when the aileron and rudder are added simultaneously to cause the aircraft to bank to the desired position. A small amount of backpressure is added to the elevator to keep the nose up and maintain altitude. When the desired amount of bank is reached, everything except the elevator is returned to neutral. The reason the aileron and rudder are returned to neutral is to stop the aircraft in the desired bank. If you were to hold the aileron and rudder in, the aircraft would continue to roll, and neither you nor your trainer aircraft is probably ready for descending rolls.

The elevator should be kept slightly aft of neutral to maintain altitude because an aircraft loses vertical lift any time it is in a banked configuration. To make up for this loss, a small amount of up elevator must be held through the turn.

If the ailerons produce the banking motion, then what is the rudder good for? Why is it on the aircraft at all? It is there for two very good reasons. One is to allow the pilot to have control over the yaw, or side-to-side movement, of the aircraft. The other is to overcome adverse yaw produced by the ailerons during the turn entry.

Try this little experiment the next time you fly and you should gain some insight into turns. Fly straight and level and put your feet on the floor. Pick a prominent object or reference point over the nose, and roll into a turn without the use of the rudder. The nose will actually seem to go in the opposite direction for an instant, and then it will resume its correct flight path. This phenomenon is called adverse yaw and is caused by the induced drag of the downward aileron.

Now, level the wings and start another turn using the same reference point. This time purposely lead the turn with the rudder and then apply aileron. The result will be the plane yawing in the direction of the turn and is known as a skid. With too much rudder, the plane moves laterally to the outside of the turn, as shown by the ball on the right side of the turn-and-slip indicator.

In a properly coordinated level turn using outside visual references, the nose of the aircraft will roll about a point and then continue in the direction of the turn as the bank is established. There should be no undesired yaw motion as ailerons are applied.

Let’s begin with entry into the turn. Figure shows the forward view looking from the pilot’s seat over the nose of the plane in straight and level flight. The dot in the figure is an imaginary reference point on the windscreen that is directly in front of the pilot. As you enter the turn you want to maintain level flight and not climb or descend. The best visual reference you can have is the point on the horizon on the windscreen directly in front of you, which is represented by the dot. During turns, that point will remain at almost the same relation to the horizon above the control panel as it did in level flight.

Figure illustrates when the plane is banked in a left turn. The dot shows where the horizon was during level flight. In this case the horizon has stayed on the dot, and the plane does not climb or descend during the turn. Figure shows the horizon has moved below the dot, which means the nose of the plane has risen and the plane is climbing during entry into the turn. Figure shows that the horizon has moved up in relation to the dot, meaning the nose of the plane has dropped and the plane is losing altitude. This visual reference can be verified by using the artificial horizon, altimeter, and VSI, which will also show when the plane is climbing or descending. A word of caution, though. Many student pilots become so focused on the instruments during turns that they stop looking outside the plane and stare intently at the instrument panel. When flying in VFR conditions, these instruments should verify what you are seeing by looking outside the plane, not act as your primary reference during turns.

Before you begin a turn, always look in the direction you are turning toward to make sure there are no other aircraft or obstacles in that direction of flight. In a high-wing airplane this may require you to raise the wing slightly to clear the area. Once the turn area is cleared, you can look forward again and set your horizon reference point for attitude. Apply aileron in the direction of the turn, at the same time applying just enough rudder to prevent the nose from yawing and to keep the ball centered in the turn and bank indicator.

You will also need to apply just enough up elevator to maintain your reference point on the horizon. It takes practice to become used to how much of each control should be used during a turn, and you will find that this changes not only from plane to plane, but also is affected by the airspeed.

To exit the turn you will roll the wings back to level flight, using rudder and aileron in a coordinated movement, just as when you entered the turn. As you reduce the bank, the lift vectors will again be used to keep the plane at altitude, and you will need to reduce backpressure on the control yoke.

There’s also another important factor you need to take into consideration during turns. In a shallow banked turn, from 0 to 20 degrees bank, the dihedral of the wings will attempt to restore the plane to wings-level flight, so you will need to keep ailerons input throughout the turn. In a medium banked turn, 20 to 45 degrees, the plane will have a tendency to remain in the bank, and you will be able to neutralize the ailerons to some extent once the bank has been established. In a steep banked turn, greater than 45 degrees, the plane will have a tendency to roll steeper, and you may need to feed in some opposite aileron to counteract this tendency. Remember, as you make these varying aileron inputs you will also need to adjust your rudder inputs to maintain coordinated flight.

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