曝光台 注意防骗
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notice it!).
The point to realise is that, in
dropping the nose, the angle of
attack improves enough to get lift
again, and the aircraft starts flying,
even if you keep the control column
back, but we want to recover, so
relax the back pressure, and note
how much height is lost during the
exercise, once you recover the cruise
attitude. It will be around 350 feet,
quite critical near the ground, so
applying power just after relaxing the
back pressure will reduce this to a
minimum, sometimes down to
below 100 feet.
Spinning
When spinning, the aircraft is out of
control in all three axes of flight. It
results from uneven stalling. A spin
is basically a stall that is not straight.
That is, you are turning and
descending with one wing (the
downgoing one) in a permanent stall,
hence the spin. The effect is a
continuous roll, which causes yaw.
Left to itself, the aircraft will not
recover, as long as the one wing
remains stalled.
You can't use aileron to get out of a
spin, because of aileron drag making
the condition worse, but rudder is
available, so you shove in a bootful
in the opposite direction to the turn,
until the yaw stops. Then relax the
back pressure on the elevator to
pitch the nose down and reduce the
angle of attack on the stalled wing
(this may be done at the same time,
depending on the machine). Do not
use ailerons, and pull out of the dive
once you have some airspeed. Then
apply power as necessary.
The aircraft must stall first, so if you
avoid stalling you won't get into a
spin. To start a spin deliberately,
shove in a bootful of rudder at the
point of the stall.
Before performing any manoeuvres,
however, you should do:
The HASELL Checks
Remember these well, as they are
useful throughout your flying,
particularly with steep turns:
· Height – are you high enough to
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
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).
196 Canadian Professional Pilot Studies
· 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
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