)--The proportion of length to maximum width.

=Flying Position=--A special position in which an aeroplane must be placed
when rigging it or making adjustments. It varies with different types of
aeroplanes. Would be more correctly described as "rigging position."

=Fuselage=--That part of an aeroplane containing the pilot, and to which
is fixed the tail-plane. [12]

=Fin=--Additional keel-surface, usually mounted at the rear of an
aeroplane. [13]

=Flange= (_of a rib_)--That horizontal part of a rib which prevents it
from bending sideways. [14]

=Flight=--The sustenance of a body heavier than air by means of its action
upon the air.

=Foot-pound=--A measure of work representing the weight of 1 lb. raised
1 foot.

=Fairing=--Usually made of thin sheet aluminium, wood, or a light
construction of wood and fabric; and bent round detrimental surface in
order to give it a "fair" or "stream-like" shape. [15]

=Gravity=--Is the force of the Earth's attraction upon a body. It
decreases with increase of distance from the Earth. See "Weight."

=Gravity, Specific=--

Density of substance
--------------------
Density of water.

Thus, if the density of water is 10 lb. per unit volume, the same
unit volume of petrol, if weighing 7 lb., would be said to have a
specific gravity of 7/10, _i.e._, 0.7.

=Gap= (_of an aeroplane_)--The distance between the upper and lower
surfaces of a biplane. In a triplane or multiplane, the distance between
any two of its surfaces. [16]

=Gap, Propeller=--The distance, measured in the direction of the thrust,
between the spiral courses of the blades.

=Girder=--A structure designed to resist bending, and to combine lightness
and strength.

=Gyroscope=--A heavy circular wheel revolving at high speed, the effect of
which is a tendency to maintain its plane of rotation against disturbing
forces.

=Hangar=--An aeroplane shed.

=Head-resistance=--Drift. The resistance of the air to the passage of
a body.

=Helicopter=--An air-screw revolving about a vertical axis, the direction
of its thrust being opposed to gravity.

=Horizontal Equivalent=--The plan view of a body whatever its attitude
may be.

=Impulse=--A force causing a body to gain or lose momentum.

=Inclinometer=--A curved form of spirit-level used for indicating the
attitude of a body relative to the horizontal.

=Instability=--An inherent tendency of a body, which, if the body is
disturbed, ca