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· Nose – the front part of the
aircraft, where the cockpit is.
· Tail – the rearmost part, with
the rudder assembly and
horizontal stabiliser. Sometimes
known as the empennage.
· Wings – the lift producing
surfaces, traditionally forward of
the tailplane, but a canard has
them the other way round. In a
helicopter, the rotor blades are
the equivalent.
· Ailerons – moveable surfaces on
the rear of the wings, at the
outer ends, that alter the way
the wing produces lift, in order
to make it go up or down, most
useful when turning.
· Stall – a condition of flight
where the wings stop producing
lift and the aircraft is no longer
able to stay airborne, when the
4 JAR Private Pilot Studies
machine is not going fast
enough for the conditions.
· Angle of Attack – the angle
formed between the wing and
its path through the air.
The airframe is the complete structure
of an aircraft, without the engines
and instruments. It will be as light
and as strong as possible, because
many forces are encountered in
flight, like compression, tension, torsion,
shearing and bending, so stuff like
wood, fabric, aluminium or carbon
fibre are used (aluminium is too soft
by itself, so it will be mixed with
copper, manganese or magnesium
for strength). Instead of being solid,
where bulk is needed, a honeycomb
construction will keep things light. This
is a framework made of short
hexagonal tubes covered over both
open ends by metal sheeting.
The fuselage is where the pilot,
passengers and cargo are placed, and
to which any wings, tailplanes,
tailbooms and main rotors are
attached. Older aircraft will be made
of a truss construction, or frame and skin,
where aluminium or steel tubing is
joined in a series of triangular shapes
(like the tail boom of the Bell 47
helicopter), then covered with metal
or fabric (in this case, the metal acts
merely as a cover, making no
contribution towards strength). One
disadvantage is that cross bracing
takes up a lot of space.
More modern machines use
monocoque, which is a development of
stressed skin, where the outside
covering itself is rigid and takes the
stresses of flight, and supporting
devices inside, like formers held
together by stringers, or longerons,
provide the shaping (this is also a
typical method used on the tail
booms of most modern helicopters).
Formers give the fuselage its basic
shape, and are assembled one after
the other, changing in size as
required. They will absorb torsion and
bending loads. Longerons run fore and
aft, keeping the formers together,
spreading the load between them
and stiffening the structure in
general. Bulkheads are similar to
formers, but tend to be found at
both ends of the fuselage, at each
end of a compartment, or when
more strength is required.
A firewall is a fireproof partition that
separates the engine compartment
from the cabin. It is normally made
of stainless steel.
In a wing, ribs are the equivalent of
formers, and they are held in place
with spars, which perform a similar
function to longerons. Modern
wings will also contain fuel tanks,
which may or may not contribute to
the strength of the wing.
An egg is a good example of a
monocoque structure, which is
handy, as cocque is French for eggshell.
Aside from saving weight, the big
advantage of monocoque is that it
leaves more space inside. Older
flying boats, made of wood, were
among the earliest examples.
Airflow
Air is a liquid medium, meaning that
it behaves rather like water (as is
shown by submerged aircraft, which
will "fly" to the bottom of the sea,
miles away from where they splash
down). It is also compressible, and
can flow and change its shape.
Principles of Flight 5
The speed at which an object moves
through the air is called the airspeed,
and it doesn't matter whether the
wind flows over it, or the object
itself moves – the effects are the
same. Up to a certain critical
airspeed, airflow round a body is
quite well-behaved, after which it
breaks up to form vortices that may
interfere with any lifting action.
The Aerofoil (or Airfoil)
This is the official name for a wing,
or any other device that creates a lift
reaction out of thin air (in order to
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