|
Pitch, Yaw, Roll and
throttle
This diagram shows the main parts and controls of an aircraft.
The primary flight controls on any aeroplane are: Pitch, Roll, Yaw,
Throttle.
The following descriptions give an explanation of the effect of each
control in isolation, for a theoretical aircraft. Obviously in flight,
control are operated together, and there are also secondary effects
of controls to consider.
|
Pitch changes raise or lower the nose of the aircraft. This
effect is caused by the operation of the elevator.
As the elevator is raised, the force of the airflow pushes
the tail down, rotating the aircraft about the balance point
and raising the nose.
Secondary effect of pitch:
If the elevator is used to pitch the nose
of the aircraft up, this has the secondary effect of increasing
the angle of attack of the wing and so more lift is generated
which will make the aircraft climb, however at the same time
the change of attitude will increase the drag of the aircraft
which will tend to slow it down and cause it to descend. So,
provided the engine output remains the same, the secondary
effects of the elevator are to control the speed of the aircraft.
|
|
|
Roll is a rotation around the long axis of the fuselage. This effect
is caused by the operation of the ailerons.
To roll left, the left aileron is raised and the right aileron
lowered. The combined effects of the airflow on the controls
lifts the right wing and lowers the left wing. The operation
is reversed to roll right.
Secondary effect of roll:
If the stick is moved to the left the aircraft will bank to
the left. As the lift always acts at 90º to the wing, and
weight always acts straight down, the resultant imbalance
of forces causes the aircraft to sideslip to the left.
Also, his sideslip causes
a flow of air towards the fuselage
sides. As there will be more area behind the Centre of Gravity
than in front of it, the resultant force will tend to rotate
the aircraft causing it to yaw.
|
|
|
Yaw is a horizontal rotation around the vertical axis of
the aircraft, and is initiated by the rudder.
If the rudder is deflected left, the pressure from the airflow
pushes the back around and the aircraft rotates around the
vertical axis. Right rudder makes it rotate in the opposite
direction. In the absence of any other control inputs, the
aircraft will carry on the original direction of flight but
with a sideways motion; it will only turn as a consequence
of the secondary effects of controls.
Secondary effect of yaw:
Application of the rudder causes the model to yaw from
side to side. This yaw means that the wing on the outside
of the turn is moving faster through the air, while the
inside wing moves slower. This speed change generates more
lift from the outside wing and less from the inner, causing
the aircraft to roll in the direction of the turn. The application
of rudder then, causes first a yaw, followed by a roll.
It is this secondary effect that allows aileron-less rudder
only models to be controlled.
|
|
|
Controls the amount of power the engine produces. Contrary to
what you may see at the flying field, most models are not required
to be flown around at full throttle all the time!
Opening the
throttle will cause the aircraft to speed up, thus creating more
lift, resulting in a climb. Closing it will cause the aircraft
to slow down, reducing the lift and hence making the aircraft
descend. |
|
|
