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controlling the aircraft
The airplane is controlled by deflection of flight
control surfaces. These are hinged or movable
surfaces with which the pilot adjusts the
airplane's attitude during takeoff, flight
manoeuvring, and landing (airplane attitude refers
to whether the airplane is pointing up, down,
etc.). The flight control surfaces are operated by
the pilot through connecting linkage to the rudder
pedals and a control yoke.
The
control yoke
is similar to the steering wheel of a car.
However, you can push and pull it in addition to
turning it. The push/pull dimension controls the
third direction (up and down). Remember, a car
can only go straight or turn (move in two
dimensions), but an airplane can go straight,
turn, or move up and down.
control yokes rudder pedals and panel of a Cessna 152 trainer
The
rudder
is attached to the vertical stabilizer.
Controlled by the rudder pedals, the rudder is
used by the pilot to control the direction (left
or right) of yaw about the airplane's vertical
axis for minor adjustments. It is NOT used to
make the airplane turn, as is often erroneously
believed. Banking the airplane makes it turn. axes of rotation
The airplane can rotate around one, two, or all
three axes simultaneously. Think of these axes as
imaginary axles around which the airplane turns,
much as a wheel would turn around axles positioned
in these same three directions.
flight controls and control surfaces
(see the illustration below.)
Lateral
(pitch) axis -- an imaginary line from wingtip
to wingtip
Rotation about the lateral axis is called
pitch and is controlled by the elevator.
The rotation is similar to a seesaw. The bar
holding the seesaw is the lateral axis.
This is known as the airplane's pitch
attitude.
secondary effect of elevator actuation
The primary effect is to change the aircraft's
pitch. The secondary effect will change the
speed.
Climbing will slow the plane and descending in
increase its speed.
Elevators
The
control yoke is connected by means of wires, rods or
hydraulics to the tail section's elevators. By
moving the yoke, the pilot can change the position
of the elevators. When the control column is pushed
in, the elevators move down, pitching the tail of
the airplane up and the nose down, rolling the
airplane down. When pulling the control column back
makes the elevators move up, bringing the tail of
the airplane down and the nose up, pitching the
airplane upwards.
click arrows to operate movie
Longitudinal
(roll) axis -- an imaginary line
from the nose to the tail
Rotation about the longitudinal axis is called
roll and is controlled by the
outboard movable portions of each wing: the
ailerons. The term "aileron" is
the French word for "little wing." Ailerons
are located on the trailing (rear) edge of
each wing near the outer tips. When deflected
up or down, they in effect change the wing's
camber (curvature) and its angle of attack.
This changes the wing's lift and drag
characteristics.
Their primary use is to
bank (roll) the
airplane around its longitudinal axis. The
banking of the wings results in the airplane
turning in the direction of the bank, i.e.,
toward the direction of the low wing.
The
ailerons are interconnected in the control
system to operate simultaneously in opposite
directions of each other. As the aileron on
one wing is deflected downward, the aileron on
the opposite wing is deflected upward.
The
ailerons are controlled by turning the control
yoke.
secondary effect of aileron actuation
The ailerons
primarily control bank. However because the
air underneath a wing is denser than that
above it, the lowering aileron causes more
drag on its side than the rising aileron.
Using ailerons causes a small amount of yaw to
occur. This is more pronounced for light
aircraft with long wings, such as gliders. It
is usually counteracted by the pilot with the
rudder. Another most import consideration is
that the stall speed of the aircraft
increases with the angle of roll. Large
angles of bank at slow speed may very well
result in a stall and spin.
click arrows to operate movie
Vertical
(yaw) axis -- an imaginary line
extending vertically through the intersection of
the lateral and longitudinal axes
Rotation about the vertical axis is called yaw
and is controlled by the rudder. This rotation
is referred to as directional control or
directional stability.
The
rotation is similar to a weather vane, in
which the post holding the vane is the
vertical axis but the rotation is directional.
Rudder
The
rudder
is attached to the vertical stabilizer.
Controlled by the rudder pedals, the rudder is
used by the pilot to control the direction (left
or right) of yaw about the airplane's vertical
axis for minor adjustments. It is NOT used to
make the airplane turn, as is often erroneously
believed. Banking the airplane makes it turn.
When the foot pressure on the left rudder pedal
moves the rudder to the left, causing the nose of
the airplane to move to the left.
When the foot pressure on the right rudder pedal
moves the rudder to the right, causing the nose of
the airplane to move to the right.
secondary effect of rudder actuation
Using the rudder causes
one wing to move forward faster than the other.
Increased speed means increased lift, and hence
rudder use causes a small roll effect. For this
reason ailerons and rudder are generally used
together on light aircraft.
click arrows to operate movie
Power
The application of power will
increase the aircraft speed with a secondary effect
of climb. A reduction in power will reduce speed
with a secondary effect of descent.
click here to operate movie
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