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perform the exercise and to
recover if something should
happen, without hitting the
ground?
·  Airframe – clean – flaps are in,
undercarriage is up, etc.
·  Security – hatches and harness all
secure (i.e. doors closed and
seat belts done up), no loose
20 Canadian Private Pilot Studies
articles in the cabin that could
fly about and injure you, etc.
·  Engine – fuel is on, and enough
for what you want to do, with
temperatures and pressures OK,
carb heat green, etc. (carb heat
should be on before reducing
power below a certain RPM, as
it won't have enough power to
defrost if any already exists).
·  Location – no good wondering
where you are when the engine
stops, better find out now! Also,
make sure you are not over
anywhere you are not supposed
to be, like congested areas,
water, etc.
·  Lookout – make sure there is no
traffic above, below or around.
Do a couple of turns to make
sure, but not a steep turn at this
stage, because you will learn
how to do them later!
Note: the above checks are slightly
different from those in current
textbooks – they were the ones I was
taught, and I believe the better ones.
Low and Slow
This manoeuvre, which is defined as
operating somewhere between stall
and endurance speeds, can kill the
unwary. It's commonly used on
pipeline inspections, or police
patrols, and is especially dangerous
with steep turns. When banking hard
over, your lifting aileron is fully
deflected, so you can turn.
Unfortunately, it's also producing
maximum drag, which will tend to
cause an adverse yaw in the opposite
direction, that is, the aircraft wants
to go right, but is being forced left,
or whatever. In contrast, the aileron
on the other wing has very little
profile above it, so is producing very
little drag. It isn't just the ailerons –
the wing rolling motion doesn't help
the situation, but the point is that, if
you don't use rudder to counteract
this, the wing causing the yaw slows
down and produces less lift, which
will stop it rising as told to by the
aileron. The other wing moves
faster, and gets more lift. The end
result is that you roll the wrong way,
or at least the Wright Brothers did.
Modern design methods have
reduced the risks in the normal flight
envelope, but when in extreme
situations, such as in a steep turn,
near the stall (and don't forget that a
stall can happen at any speed with
the wrong angle of attack) it may
well catch you by surprise if you use
the ailerons too abruptly, especially
when the lifting wing stalls and puts
you in a spin, which is just what you
don't want at 200 feet (remember the
aileron's purpose is to temporarily
increase the angle of attack). Tip:
use ailerons last out of a steep turn.
Put the control column forward and
use opposite rudder first,
remembering that the controls are
much less effective at slower speeds.
This can also be a problem when
taking off from a short strip, with
both wings at a high angle of attack.
Sharp movement one way or the
other will increase the angle on the
lifting wing and stall it the wrong
way. Again, modern design, such as a
twist in the wing that makes the tip
ride flatter, has improved matters,
but try it in a Cessna 152 (a long way
off the ground!) to see what I mean.
Principles of Flight 21
Stability
The stability characteristics of an
aeroplane describe its ability to
return to its flight path after a
disturbance without input from the
controls. A stable aircraft is easier to
fly and more pleasant, but one too
much that way will not be so
manoeuvreable. The static stability is
the initial tendency, while the dynamic
stability concerns the overall tendency,
after a series of ever-decreasing
oscillations – having one does not
necessarily lead to the other. Its
significance lies not just with you
nudging controls by accident, but if
you encounter turbulence, which has
the most to do with knocking your
aircraft off its flight path.
If positive stability is a tendency to
return to the flight path, negative
stability tends to move it further
away in increasing movements:
You could then say that the aircraft
is unstable. This could be a problem
when the increasing oscillations lead
you to stall or dive. Be aware that a
　
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