Chord—Usually taken to be a straight line between the trailing and leading edges of a surface.
Cell—The whole of the lower surface, that part of the upper surface directly over it, together with the struts and wires holding them together.
Centre (Line) of Pressure—A line running from wing-tip to wing-tip, and through which all the air forces acting upon the surface may be said to act, or about which they may be said to balance.
Centre (Line) of Pressure, Resultant—A line transverse to the longitudinal axis, and the position of which is the resultant of the centres of pressure of two or more surfaces.
Centre of Gravity—The centre of weight.
Cabane—A combination of two pylons, situated over the fuselage, and from which anti-lift wires are suspended.
Cloche—Literally “bell.” Is applied to the bell-shaped construction which forms the lower part of the pilot's control lever in a Bleriot monoplane, and to which the control cables are attached.
Centrifugal Force—Every body which moves in a curved path is urged outwards from the centre of the curve by a force termed “centrifugal.”
Control Lever—A lever by means of which the controlling surfaces are operated. It usually operates the ailerons and elevator. The “joy-stick”.
Cavitation, Propeller—The tendency to produce a cavity in the air.