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should be shown how to secure
seatbelts so they don't flap around in
flight, as part of a proper briefing.
There should be no loose articles in
the cabin, and seats must be
removed, as must be dual controls if
one intends to drop from the front
seat (of a helicopter). There should
be no other passengers.
Don't use static lines and remove the
doors (check the Flight Manual for
limitations on flight without them).
A typical freefall drop needs one
pass over the drop site into wind at
approximately 2000 feet, where the
jumpmaster will drop weighted
paper markers. You then commence
climbing to the drop height, turning
downwind and keeping the markers
in view all the time. When at drop
height, come over the site again at
about 60 knots into wind, where the
jumpmaster will guide you to where
he wants to be.
When dropping, use both sides of
the aircraft if possible (difficult in a
Bell 47), so the lateral centre of
gravity limits are not exceeded – this
is one of those times when you
might want to calculate it for takeoff
and landing. The helicopter should
be level, above 2000' agl with an
airspeed between 20-70 kts IAS.
Mountain Flying
In the mountains, general principles
common to other areas will be vastly
different. You must be prepared to
adapt your flying techniques as the
need arises, for the peculiarities of
the region and the type of aircraft. In
other words, have not only Plan A,
but Plan B, C, etc. up your sleeve,
because, very often, once you’ve
looked at a site and gone round for
finals, you will find a cloud has got
there before you! You cannot afford
to assume that a particular situation
is the same as, or similar to, any
other you might have encountered
previously. You can also expect fog,
66 The Helicopter Pilot’s Handbook
especially in the early morning,
which will often stick to the sides of
valleys for quite some time.
Sometimes, you can create your own
clouds, by pulling down warm air
from an inversion above.
In UK, mountainous areas include
Scotland and Wales, the Lake and
Peak Districts, and generally any hilly
country above 1500 feet amsl,
although a geologist would probably
expect to see 2000. In many other
parts of the world, these would be
considered as just foothills, as one
description of mountain flying
includes a reference to 5000 feet
Density Altitude. Actually, it reads:
"experience in maneuvring a helicopter
at density altitudes of over 5000 feet to
include numerous takeoffs and landings
in situations indicative to difficult
mountainous terrain. This terrain
consists of abrupt, rapidly rising terrain
resulting in a high land mass projecting
above its surroundings, wherein complex
structures in which folding, faulting, and
igneous activity have taken part. These
mountainous areas produce vertical
mountain winds, turbulence associated
with mountain waves, producing abrupt
changes in wind direction often resulting
in up flowing or down flowing air
currents. In the contiguous United
States, the boundaries of these
mountainous areas are defined in the
aeronautical information manual."
In Canada, look out for Designated
Mountain Areas, which naturally
include the Rockies, extending into
the USA (don't blame me for the
English above - it was written by the
US Forestry people).
However, air behaves the same way
round pointy bits of ground
whatever its height above sea level,
and this includes flying around
buildings (we will look at laminar
flow shortly). The big difference
here is that you have less power to
play with, hence the mention of
density altitude.
Performance changes drastically
when both temperature and height
increase—just the opposite to flying
in cold weather, but you knew that
anyway. As far as altitude is
concerned, low-level operations
(below about 5000 feet) probably
won't need you to get too
concerned, apart from taking notice
of airspeed placards and power
limitations, because some of the
power lost with altitude is regained
with cooler temperatures. You will
find that at least 75% power is
available to a fair height, but be
careful (some pilots report no real
difference up to 8500 feet).
Power available is reduced with
height (and temperature), and rotors
turn at the same speed, so, as you
increase altitude, higher pitch and
　
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本文鏈接地址：The Helicopter Pilot’s Handbook(44)