from the vertical position. If you do not increase
lift, its vertical component is insufficient to
maintain the aircraft at a constant altitude. A
change in pitch attitude to increase the angle of
attack of the wings is used to prevent a loss in
altitude. A few degrees of bank angle requires an
imperceptibly small pitch change. A 90-degree
bank in level flight (no altitude change) is
theoretically impossible because of the absence
of vertical lift. As the bank angle changes,
coordination between ailerons and elevators is
necessary to prevent a loss in altitude.
To return to level flight, increase lift on the
left wing by lowering its aileron into the higher
pressure area beneath the airfoil. Reduce lift on
the right wing by raising its aileron into the lower
pressure area at the top of the airfoil. As the wings
become level, neutralize the ailerons.
Movement about the vertical axis is yaw.
Usually this movement is undesirable in an
aircraft. Use the rudder to correct any tendency
of the aircraft to yaw. The rudder is NOT used
to turn the aircraft (change heading).
When placing the ailerons into the airstream,
the aircraft has a tendency to yaw. In banking to
the right, the aircraft produces more lift and drag
on the left wing, and less lift and drag on the right
wing. Even though the intention is to turn to the
right by going into a right bank, the initial
tendency is for the nose of the aircraft to go to
the left. This happens because of the increased
drag on the left wing and decreased drag on the
right wing. This is adverse yaw; you compensate
for it by displacing the rudder in the same
direction as the intended turn.
Figure 8-9.-Flight controls. (A) Elevator and aileron;
(B) Rudder.
If an aircraft in a turn tends to slip into the
inside of the turn or skid to the outside of the turn,
this is also yaw. You also compensate for it by
to operate the rudder pedals. Pressure on either
using the rudder. Many other things may cause
rudder pedal causes rudder deflection in that
yaw, such as the engines on one wing of a
direction.
multiengined aircraft producing more power than
Weight distribution in an aircraft varies for
the engines on the other wing.
many reasons. For example, fuel may be used
You can see, then, when you place a fixed-
faster from one wing tank than from the other,
wing aircraft in a bank angle, coordination
allowing that wing to become lighter. In large
between all three controls--ailerons, elevators,
aircraft where crew members or passengers walk
and rudder--is necessary. The pilot accomplishes
around, the balance point, called the center of
control of elevators, ailerons, and rudder through
gravity (CG), shifts whenever someone changes
the use of a control stick and rudder pedals
position in the aircraft. As fuel is used, the aircraft
gross weight reduces. The pilot must reduce the
control stick right or left in the direction of the
angle of attack of the wings to lessen lift and
intended turn (fig. 8-9, view A). Aft force on the
prevent a gain in altitude.
control stick raises the elevator and causes the
The pilot must use control pressures to
nose to pitch up. Forward pressure on the control
compensate for these unbalanced flight condi-
stick lowers the elevator and causes the nose to
tions. Several methods are used to reduce these
8-7