How do we fly the
Copyright © Julien Evans
2012, 2016, 2018
Published by Steemrok
All rights reserved. No
part of this book may be copied, recorded,
reproduced or transmitted in any form or by any means without the
written permission of the Publisher
readers with little or no knowledge of the subject, the purpose of this
booklet is to describe basic operation of light aircraft. The contents
are based on excerpts from the book 'Handling
that this booklet is not intended to teach aircraft handling or
piloting procedures, which are the domain of professional instructors.
if the reader is perhaps thinking about taking a trial lesson or might
find himself or herself a passenger in a light aircraft whose pilot
intends to offer them a chance to take the controls, these notes may be
The main features of the
typical modern light
aircraft are shown in Figure 1.
Figure 2 shows the layout of controls and instruments in the cabin.
Although dual controls are
standard on most
aircraft, the pilot usually occupies the left hand seat, which is why
the flight instruments are installed on the left side of the panel. The
that concern us are the control
and 24), the throttle (16), the flap lever (26) and
shows the power output from the engine.
3 shows the layout of the flight instruments. The ones that concern us
are the airspeed
and the direction
The most obvious
difference between aircraft and ground based vehicles
the freedom of aircraft to move in the third dimension. The pilot is
able to control the vertical (up-and-down) flight path of the aircraft
as well as its horizontal (left-and-right) flight path and the speed at
which it is flying. The flight path is controlled by inputs from the
control wheel. Speed is controlled by either control wheel inputs or
engine power setting.
The Primary Flight
primary flight controls are the ailerons,
ailerons and elevators are connected to the control wheel and
rudder to the rudder
pedals. The control wheel can be turned from side
to side (like a car's steering wheel). Additionally it can be pulled
towards the pilot or pushed away from him or her. When
the control wheel is pulled back, the elevators move upwards, and vice
versa (Figure 4).
the elevator position determines the airflow
pattern past the tailplane. If the pilot pulls the wheel back the
aircraft will raise its nose and its speed will decrease. If he or she
pushes it forwards the
aircraft's nose will drop and its speed will increase. Figure
5 shows the pilot's view.
control wheel is turned to
the left, the aileron on the left wing moves up and that on the right
wing moves down. If the wheel is moved to the right the ailerons move
in the opposite sense (Figure 6).
In flight, the effect of
aileron movement is to change the airflow patterns over the wings. If
the pilot moves the wheel to the left the left wing will go down and
the right wing up. This motion is called rolling to the
the wheel to the right makes the aircraft roll to the right.
When the control wheel is centred the aircraft will maintain the angle of bank it has
attained (Figure 7).
Figure 8 shows an angle
of bank of 30° from the pilot's view.
the left rudder pedal is pushed forward the rudder moves to the left,
and vice versa. For manoeuvring on the ground the rudder pedals also
activate the nosewheel steering (Figure 9).
In flight, the rudder position
determines the airflow pattern past the fin, which consequently affects
the force experienced by the fin. For example, if the pilot pushes the
left pedal forward, the nose of the aircraft moves to the left (because
the tail moves to the right). If he or she pushes the right pedal
forward then the nose movement will be to the right. This motion is
Note that we don't turn
the aircraft using the rudder
pedals. We'll see why later .
If the pilot
pushes the throttle
forward, the fuel flow to the engine is increased
and it develops greater power, which means that the propeller delivers
Retarding the throttle reduces propeller thrust.
Attitude and Pitch
pitch attitude relates to the aircraft's nose position in
sense. The pilot assesses the aircraft's pitch attitude by reference to
the earth's horizon, as shown in the previous diagrams.
Of course, these pitching motions change the angle of
attack of the wings and therefore affect the wing lift, which in turn
affects the aircraft's flight path and speed, as we have already noted.
Attitude and Roll
bank attitude relates to the lateral position of the
wings. As we have seen, if the
wings are not level, they are said to be in a banked attitude, which
again the pilot
assesses by reference to
the earth's horizon.
second factor affecting the aircraft's flight path is its airspeed. The
pilot can control speed by two methods. One is to change the power
setting of the engine. For example, increasing the engine power in
level flight (not climbing or descending) makes the aircraft
accelerate, and vice versa. The second method of controlling speed is
by change of pitch attitude, as we noted above. The method chosen
depends on the phase of flight.
Flight Path and
combination of pitch
attitude setting and power
setting will determine
whether the aircraft flies level or climbs or descends, and also the
speed at which it flies. To make the aircraft achieve a desired
vertical flight path and speed the pilot must select the appropriate
pitch attitude and power setting. Only one combination will give the
correct result. Expanding what was said above about phases of flight,
the pitch attitude chosen by the pilot is sometimes used to control the
vertical flight path of the aircraft and sometimes to control its speed.
level flight the aircraft neither gains nor loses altitude. In other
words the indication on the altimeter remains constant. In level flight
the vertical flight path is
controlled by pitch attitude and the speed is controlled by power
setting. If an undesired increase in altitude is observed, the pilot
will move the control wheel slightly forward to set a lower pitch
attitude and thus correct the error. If the speed is too high, the
pilot will retard the throttle slightly. An increase of power will be
necessary if the speed is too low. Figure 11 shows a typical cruise
climbing flight the engine is set to climb power. The aircraft's speed
is therefore controlled by pitch attitude. If the indicated speed is
too low, the pilot will move the control wheel forward to set a lower
pitch attitude. If the speed is too high, a higher attitude will be
needed. Figure 12 shows a typical climb attitude.
controls are used as for the climb. In other words the speed is
controlled by pitch attitude and the rate of descent is controlled by
power. Figure 13 shows a descent at cruising speed with the engine at
If engine power is increased the aircraft will begin to
accelerate and so to maintain this speed a higher nose attitude will be
needed. This new combination of pitch attitude and power setting will
result in a reduced rate of descent and hence a shallower descent
gradient. When approaching to land, however, the controls are used
differently. Now the pitch attitude is adjusted as necessary to control
the vertical flight path, in this case to achieve the correct approach
angle, while power is set as necessary to control speed.
the wings are level the aircraft will fly straight and the direction
indicator will show a constant heading. The direction
indicator is referenced to
magnetic north, which is the datum for navigation. To start a turn, the
control wheel is turned in the desired direction until the desired bank
attitude is attained. Then the wheel is centred again. The bank will
remain at the attained attitude and the tilted lift
force will make the aircraft turn, with
the direction indicator showing a changing heading.
the difference between turning a car and turning an aircraft. In a car
the steering wheel must be held in its displaced position to maintain
the turn, whereas the aircraft will turn whenever the wings are banked,
even though the control wheel is centred. Therefore to stop the turn
the control wheel must be turned away from the lower wing to level the
wings again. If the wings are level the aircraft will fly straight. If
they are not, the aircraft will turn towards the lower wing. The
greater the angle of bank, the more quickly the aircraft will turn. Of
course, this is true regardless of whether it is climbing, descending
or flying level.
Is The Rudder For?
Why do we bank
the wings to turn the aircraft? Why don't we use the rudder? The answer
is that the turn has to be balanced.
If we used the rudder to turn, the
aircraft would skid, flying sideways through the air, with its
occupants feeling a sideways force. If however we bank the wings to
turn, the outward force is balanced by the tilted attitude and so the
occupants of the aircraft feel no sideways force one way or the other.
Aerodynamically, this technique is the best to follow because the
airflow past the aircraft is symmetrical and therefore no extra drag is
Why do we need a rudder
at all, then? Well, there are
times when we can't control heading with wing bank, for example during
take-off and landing. Keeping straight on the runway will require
inputs from the rudder.
The lowering and raising
the flaps is controlled by the flap lever (Figure 14).
To fly safely at
low speeds the flaps are lowered to increase the wing curvature and so
generate more lift. On grass runways take-off is often made with flaps
partially lowered to reduce length of ground run required. For the
landing they are selected fully down.
pilot opens the throttle fully and concentrates on keeping the aircraft
running straight along the centreline, using the rudder pedals (but not
the brakes at the tops of the pedals). Initially the steering is
through the nosewheel steering mechanism but as airspeed builds up the
rudder itself becomes effective. Figure 15 shows the view ahead at the
start of the take-off run.
At rotation speed the pilot pulls
the control wheel back to lift, or rotate, the nose to the take-off
attitude. During rotation, the angle of attack of the wings increases
and so the lift they generate also increases. Eventually the lift force
will exceed the aircraft's weight and the wheels will leave the ground.
Now the pilot
concentrates on adjusting pitch
attitude to maintain the correct climb speed. Any turning required will
be done by bank inputs from the control wheel (not the rudder!).
control wheel inputs the pilot must maintain the correct vertical
flight path to the runway threshold, simultaneously adjusting
engine power as necessary to hold the correct final approach speed.
The pilot must also keep the aircraft lined up with the runway
centreline, using bank inputs to control heading (Figure 16).
aircraft nears the runway the pilot must raise the nose, or
arrest the descent rate, simultaneously retarding the
throttle to idle. This manoeuvre is judged visually, rather than by
reference to the instruments. The aircraft will attain a level flight
path just above the runway. As it loses speed it will start to sink,
which is prevented by raising the nose progressively (the hold off)
until the landing attitude has been achieved (Figure 17).
At this point it
is allowed to touch down on its mainwheels, followed by the nosewheel.
To keep straight during the landing roll requires rudder inputs (the
control wheel will no longer be of any use). The brakes are applied as
necessary to slow to
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