The Aeroplane Speaks. Fifth Edition

=Energy=--Stored work. For instance, a given weight of coal or petroleum stores a given quantity of energy which may be expressed in foot-pounds. =Extension=--That part of the upper surface extending beyond the span of the lower surface. [9] =Edge, Leading=--The front edge of a surface relative to its normal direction of motion. [10] =Edge, Trailing=--The rear edge of a surface relative to its normal direction of motion. [11] =Factor of Safety=--Usually taken to mean the result found by dividing the stress at which a body will collapse by the maximum stress it will be called upon to bear. =Fineness= (of stream-line)--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."