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acceleration/deceleration and longer
distances. TODR will increase by
20% for each 10% increase in weight
and LDR 10% per 10% increase in
weight (factor by 1.2 and 1.1). Very
few aircraft allow you to fill all the
seats with full fuel.
Some manuals give take-off and
landing weights that should not be
exceeded at specific combinations of
altitude and temperature, thus
ensuring that climb performance is
not compromised. These are known
as WAT limits (Weight, Altitude and
Temperature)
Leading Edge Protective Tape
Used on leading edges of rotor
blades to protect against wear and
tear from dust or precipitation. A
partial loss of it can dramatically
affect aerodynamic efficiency,
resulting in substantial increases in
power when hovering. It will also
cause a slight loss in RPM during
autorotation.
The most likely time for the stuff to
come off is during or after flight
through rain, which is just when it's
needed, so you need to check it
before take-off. If it looks like
wearing out, then remove or repair it
before the next flight, removing an
equivalent amount from each blade,
as it may have also been used for
balancing. It will be put on in short
strips of anything between 6-18
inches (so you're not flying with a
great length of it hanging off) which
should be removed as a whole—
don't just cut bits away.
If tape comes off in flight (with a
distinctive "chuffing" sound,
sometimes accompanied by vertical
bounce), reduce power and speed
and make gentle manoeuvres while
landing. If it comes off before
landing, just carry on.
Engine Failure and
Autorotations
This part is not meant to cover
(again) the basic stuff you learn in
flying training, but to offer advice
that would be useful to a working
pilot, who is very often over trees, or
in remote places that the student is
routinely taught to avoid. In short, it
talks about surviving a potential
crash, because you won't always find
yourself over the clear areas you
need for training.
Engine failure in a helicopter is
detected by a noticeable decrease in
engine noise (!), yaw in the same
direction as blade rotation, loss in
height/speed and RPMs, plus
ENGINE OUT audio/visual
warnings (if fitted), because there's
so much noise you can't tell whether
the engine's still going anyway. While
speed is of the essence, there is
usually time enough to verify actual
engine failure by looking at the
instruments while you're reducing to
autorotation speed to maintain
height, certainly in a Bell, unless
you’re very heavy in a high hover
situation, such as long-lining, where
you have no time to do anything
other than dump the pole.
For all practical purposes, your
gliding distance is about equal to
your height or, put simply, what you
can see slightly above the bottom of
the windscreen. If you keep your
Techie Stuff 119
landing spot in the same place in that
area, your speed watch needn’t be so
critical (remember sight picture
approaches?). In fact, once you've
set your speed, keeping a mental
note of the attitude will enable you
to look out more. Loss of RPM at
the entry into autorotation is more
important—a higher angle of attack
from the new relative airflow as air
rushes up through the rotors will
cause enough drag to slow the rotors
drastically, especially if your weight is
high or air density low, meaning that
your blades will be at a higher pitch
angle anyway. Get that collective down,
and bring the airspeed back to autorotation
speed. Then accept the inevitable, that
you may hit something, so your
primary focus now is to ensure you
and your passengers' survival, that is,
to protect the cabin area as much as
possible. Of course, it would be nice
to save the whole ship, but don't
stretch the glide, for example,
towards a clear area and risk losing
the RPM, or having less control over
the rate of sink. Clear areas should
really be within a normal glide.
On this point, remember that the
helicopter is better able to cope with
a vertical rather than a horizontal
crash (oops, sorry, landing), since the
gear can usually take some
punishment, as is proven daily by
student pilots. You can use the tail
boom and main rotors, too,
especially in trees, mentioned below.
To ensure the horizontal element is
reduced, the best tactic will be to
　
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本文鏈接地址：The Helicopter Pilot’s Handbook(79)