Turns - P-330_wch50058

CHAPTER FOUR

T-34C CONTACT

407.

TURNS

The turn is the most complex of all the basic flight maneuvers. During the turn, coordinated use

of all three flight controls is required. Although there are other important considerations, the

first requirement for the turn is that balanced flight be maintained.

You will recall that when an airplane is flying straight and level, the total lift is acting

perpendicular to the wings and to the earth. As the airplane is banked into a turn, the lift then

becomes the resultant of two components. One, the vertical component, continues to act

perpendicular to the earth and opposes gravity. The other, the horizontal component, acts

parallel to the earth's surface and opposes centrifugal force caused by the turn. These two lift

components act at right angles to each other, causing the resultant lifting force to act

perpendicular to the banked wings of the airplane. It is this lifting force that actually turns the

airplane, not the rudder, as misinformed pilots might believe. These facts are illustrated in

Figure 4-5.

Vertical Component

of Lift

ot ft

T i

Horizontal

Centrifugal

Component

Force

ct )

Fa rce

ad Fo

Lo (G-

Weight

Figure 4-5 Turn-Bank Lift Vectors

When applying aileron to bank the airplane, the depressed or lowered aileron (on the rising wing)

produces a greater drag than the raised aileron (on the lowering wing). This increased aileron

drag, which is called adverse yaw, tends to yaw the airplane towards the rising wing, or opposite

to the desired direction of turn, while the banking action is taking effect. To counteract the

yawing tendency, rudder pressure must be applied simultaneously in the desired direction of

turn. This produces a coordinated turn.

After the bank has been established in a theoretically perfect turn in smooth air, all pressure on

the aileron control may be relaxed. The airplane will remain at the bank selected with no further

tendency to yaw since there is no longer a deflection of the ailerons. As a result, pressure may

also be relaxed on the rudder pedals, and the rudder allowed to streamline itself with the

direction of the air passing it. If pressure is maintained on the rudder after the turn is established,

the airplane will tend to skid to the outside of the turn. If a definite effort is made to center the

rudder rather than let it streamline itself to the turn, it is probable that some opposite rudder

pressure will be exerted inadvertently. This would tend to force the airplane to yaw opposite its

original turning path. As a result, the airplane would tend to slip to the inside of the turn. The

ball in the turn indicator will be displaced off-center whenever the airplane is skidding or

slipping.

4-10

FUNDAMENTAL FLIGHT CONCEPTS