Transcript Aircraft Motion and Control

Aircraft Motion and Control
Know aircraft motion and how it is controlled.
1.
2.
3.
4.
5.
6.
Identify the axes of rotation.
Identify the effects of flaps on flight.
Identify the effect of slats on flight.
Identify the effects of spoilers on flight.
Identify the effects of drag on flight.
Describe the elements of controlled flight.
Overview
1.
2.
3.
4.
5.
6.
The Axes of Rotation
Flaps
Slats
Spoilers
Drag Devices
Controlled Flight
The Axes of Rotation
• The fuselage of the conventional airplane is
the basic structure to which all the other
parts are attached. The wings, which are the
primary source of lift, have ailerons
attached to them. The tail, or empennage,
consists of the horizontal stabilizer, with
attached elevators and the vertical stabilizer,
with attached rudder.
The Axes of Rotation
• Longitudinal Axis
• Running from the tip of the nose to the tip of
the tail. This axis can be thought of as a skewer
which turns either right or left and causes
everything attached to it to turn.
The Axes of Rotation
• Longitudinal Axis
• The cause of movement or roll about this axis
(or roll axis) is the action of the ailerons.
Ailerons are attached to the wing and to the
control column in a manner that ensures one
aileron will deflect downward when the other is
deflected upward.
The Axes of Rotation
• Longitudinal Axis
• When an aileron is not perfectly aligned with
the total wing, it changes the wing’s lift
characteristics.
• To make a wing move upward, the aileron on
that wing must move downward.
• The pilot can cause a wing to lift very slightly,
or by very positive movement on the controls,
the wing can be made to rise very quickly.
The Axes of Rotation
• Longitudinal Axis
• While the one wing is moving upward the other
wing is moving downward due to the deflection
of its aileron. The reason again is a change in
the amount of the wing airfoil’s lift.
• The “up” aileron’s deflection is greater than
that of the “down” aileron. The “up” aileron
must be deflected to a greater degree in order
for it to affect the airflow and change the lift
characteristic of the wing.
The Axes of Rotation
The Axes of Rotation
• Lateral Axis
• An imaginary rod, running from one wing
tip through the fuselage and exiting the other
wing tip, forms an airplane’s lateral axis.
• Another name for the lateral axis is the pitch
axis.
• The elevator can be deflected up or down as
the pilot moves the control column backward
or forward.
The Axes of Rotation
The Axes of Rotation
• Vertical Axis
• An imaginary rod or axis which passes
through the meeting point of the longitudinal
and lateral axes. It is also referred to as the
“yaw” axis.
• The airplane turns about this axis in a sideto-side direction.
• The airplane’s rudder is responsible for the
movement about this axis.
The Axes of Rotation
Flaps
• The flaps are attached to the trailing edge of
the wing. In cruising flight, the flaps
simply continue the streamline shape of the
wing’s airfoil.
• When flaps are lowered either partially or
fully, lift and drag are increased.
Flaps
• Flaps increase the camber of the wing airfoil
for the portion of the wing that it is attached.
• This causes the air to speed up over the wing
section where the most lift is created.
• On the underside of the wing, dynamic lift is
increased.
• When landing, flaps permit the steep descent that
may be necessary to land on a short runway.
• Using flaps when taking off helps the airplane
get off the ground in a shorter distance.
Flaps
• In addition to the simple hinge flap there are
much more complicated ones.
• When an extended flap leaves a space between
the wing and flap, it is known as a slotted flap.
• This happens because the high-speed relative
wind going through the slot adds energy to the
upper wing airflow.
Flaps and Slats
Slats
• Slats are protrusions from the leading edge of
a wing.
• The secret of the slat is the slot it produces.
• In normal flight the relative wind struck the
leading edge of the slat, passed over the slot,
and continued around the airfoil.
• Modern airplanes have retractable slats.
Spoilers
• Spoilers work to destroy lift.
• Spoilers are found on various aircraft from
the jet airliner to the sailplane.
• On the jet airliners, spoilers are hinged so
that their aft portion is tilted upward into the
smooth airflow.
Spoilers
• A favorable feature about spoilers is that they
can be deployed or retracted quickly.
• The use of flaps lowers the stalling speed.
Spoilers
Drag Devices
• These devices may be located at the trailing
edges of the wings, or they may protrude
from the aircraft’s fuselage upon activation
by the pilot.
• These devices may be called dive brakes, air
brakes, dive flaps, or drag parachutes. Their
purpose is to produce a significant amount of
drag without affecting the airfoil’s lift.
Controlled Flight
• Takeoff and Climb
• After taxiing to the runway, a pre-takeoff
checklist is accomplished.
• As take off airspeed is approached, gentle back
pressure on the control wheel raises the elevator
which causes the nose to pitch upward.
• Once the nosewheel is off the runway, right
rudder is applied to counteract the left-turning
tendency, which is present under low airspeed,
high-power flight conditions.
Controlled Flight
• Takeoff and Climb
• As airspeed increases to the best rate-of-climb
airspeed, back pressure on the control wheel is
adjusted to maintain that airspeed until the first
desired altitude is reached.
• Upon reaching cruising altitude, the airplane’s
pitch attitude is reduced and the airplane
accelerates to cruising speed.
Controlled Flight
• Basic Flight Maneuvers
• Basic flight maneuvers are started from “straight
and level” flight.
• Power setting is maintained at 55 to 75 percent of
available power.
• A series of slight adjustments or corrections in pitch,
yaw, and roll are made to keep the wings level and
heading and altitude constant.
• Basic flight maneuvers include climbs, descents,
turns, and a combination of these.
Controlled Flight
• Climbs are a combination of power and “up
elevator.”
• Best angle-of-climb.
• The climb angle is steep and all available power is
used.
• Used when the pilot must rise quickly after take-off to
avoid objects at or near the end of a runway.
• Other than best-rate and best-angle climbs, most
climbs are very gentle at low angles of attack.
Controlled Flight
• Descent
• A combination of reducing power and adjusting
to maintain the desired airspeed. Airspeed is
maintained by varying pressure on the control
wheel. This varies the angle of attack and
airspeed.
• The rate of descent, measured in feet per minute,
is controlled by applying or reducing power as
needed.
Controlled Flight
• Turns
• Turns are either gentle, medium, or steep, and
they may be made when climbing, descending, or
while not gaining or losing altitude.
• Causing the airplane to turn requires smooth
coordination of aileron, rudder and elevator
controls, pressure on the control wheel and
rudder pedal should be applied simultaneously.
Controlled Flight
• Turns
• The moment a wing begins to rise in a banked
turn, it experiences more drag because of the
lowered aileron and its higher angle of attack.
• Once the coordinated turn is established, ailerons
and rudder usually are neutralized.
Controlled Flight
• Turns
• In-flight turns are measured as the number of
degrees of bank involved.
• At 60o of bank the airplane experiences twice the
normal force of gravity (2Gs).
• At 80o of bank a force of almost six times that of
normal gravity is felt.
• The average light airplane has a design limit of
approximately 3.8Gs.
• In steep turns, those of 35o or more of bank,
considerable back pressure on the control wheel
is required to produce the needed amount of lift.
Controlled Flight
• Landing
• A good landing begins with a good approach.
• Flaps are used to permit a lower approach speed
and a steeper angle of descent.
• The airspeed and rate of descent are stabilized
and the airplane is aligned with the runway
centerline as the final approach is begun.
Controlled Flight
• Landing
• When the airplane descends across the approach
end (the threshold) of the runway, power is
reduced.
• Continuing back pressure on the control wheel,
as the airplane enters ground effects and gets
closer and closer to the runway, further slows its
forward speed and rate of descent.
Controlled Flight
• Landing
• The pilot’s objective is to keep the airplane flying
safely just a few inches above the runway until it
loses flying speed.
• With the wheels of the main landing gear firmly
on the runway, the pilot applies more back
pressure on the control wheel.
Controlled Flight
• Stalls
• At the critical angle of attack, air going over a
wing will separate from the wing or “burble,”
causing the wing to lose its lift (stall).
• This speed will vary with changes in wing
configuration (flap position).
• Most airplanes give adequate warning as the
stalling speed is approached.
Controlled Flight
• Stalls
• Newer aircraft have stall warning horns and/or
lights that activate 5 to 10 knots above the
stalling speed.
• When the wing stalls, the nose of the airplane
starts dropping, even though the control wheel
may be in the full back position.
Summary
1.
2.
3.
4.
5.
6.
The Axes of Rotation
Flaps
Slats
Spoilers
Drag Devices
Controlled Flight