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pride. This makes sense, because it is
where you will spend most of your
flying life.
Correct small amounts of yaw (less
than 10°) with rudder only – larger
amounts need aileron as well to
prevent rolling. In a similar vein,
small changes in altitude are less
than 100 feet, for which you can just
use the elevator. Larger amounts
need power as well.
After initiating a manoeuvre, it will
continue unless you centralise the
controls, so, having started a turn,
for example, return the controls to
where they started when you get to
the position you want.
Turns
A "proper" turn is one in which the
aircraft is in balance, and there are
no acceleration forces, unless you are
climbing and descending
deliberately. That is, there is a
constant rate of change of direction,
maintaining height, and the forces
acting on the machine are in
equilibrium. You turn by making the
aircraft bank in the required
direction with ailerons.
Having done that, some of the lift
force is applied to the turn, so the
lift vector is reduced. You must
therefore apply some backwards
control column movement to force
the tail down and the nose up, at the
cost of a little speed (if you want to
keep the same speed, you must also
apply some power). There will also
be a yawing moment applied the
opposite way to the turn, because
the upgoing wing has more aileron
in the airflow, and is producing more
drag to slew the nose round (adverse
aileron yaw). This will need a little
rudder movement to keep the ship
straight, although this can be allowed
for in modern designs by adjusting
the movement of the ailerons, or the
shape, like the Frise aileron, which
produces a counter drag from a lip
that appears underneath the wing
when it is moved upwards. You will
also need a slight force to stop the
machine turning, because the outside
wing will be moving faster and
producing more lift.
The greater the rate of turn, the
more the lift must be increased to
maintain height, and the more the
weight artificially increases to keep
the forces balanced, which is one
good reason for not being
overweight, because you never know
when you will need the power. At
3G, for example, the weight is the
equivalent of three times what it would
be in straight and level flight.
A turn will continue unless the
controls are centralised. The nose
drops because the lift vector moves
away from its opposition to gravity
(weight). You can either increase
speed or the angle of attack, but the
latter is preferable, although power is
required for steep turns (see below).
Principles of Flight 15
To judge the right angle of attack,
you must get used to the position of
part of the aircraft against the
horizon (usually the nose or
instrument panel), which will be
different in a left or right turn. In
practice, as long as you keep that
position, you will stay level during
the turn, only checking the alitmeter
occasionally to make sure, because
you should keep the lookout going.
Remember that a bigger angle of
attack means more drag, that
requires a bigger angle, and so on.
Centrifugal force will tend to alter
the longitudinal axis of the aircraft
against the arc of the curve. Look at
the turn coordinator. A slip or skid
will alter the wing's lift-producing
characteristics and force you into
unwanted adjustments.
You need to start rolling out slightly
before the point at which you wish
to end up, otherwise you will
overshoot – you will be turning (at
an increasingly lesser rate) all the
time you are rolling out.
To roll out of a turn on a selected
heading, lead by half the angle of
bank, that is, for a 30° bank, roll out
15° before the desired heading. Use
small angles of bank for small
heading changes. Usually half the
number of degrees of heading
change is enough.
The approximate angle of bank to
produce a rate one turn may be
calculated with: (KIAS divided by
10) + 7 = bank angle. Add 5 instead
of 7 for statute miles per hour.
Use ailerons and rudder, and relax
the back pressure, otherwise the new
lift vector generated in the turn will
still be active and you will climb.
Climbing turns should be no more
than 15°. The load factor increases
with bank angle, as does the stalling
speed. Also, lift is lost with bank,
reducing the climb capability. The
　
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