F
Feathering—A form of construction in which mounting on hinges, or pivots, permits the surfaces to engage the air flatwise in one direction and to pass edgewise through it in other directions.
Fin—A fixed vertical stabilizing surface, similar in form to the fin on the back of a fish.
Fish Section—A term applied to the lengthwise section of an aircraft when the outline resembles the general shape of a fish—blunted in front and tapering toward the rear. This form is believed to encounter less resistance than any other, in passing through the air.
Fixed Wheel—A wheel in a fixed mounting, so that it does not swivel as does a caster wheel.
Flapping Flight—Flight by the up-and-down beating of wings, similar to the common flight of pigeons.
Flexible Propeller—A propeller in which the blades are frames covered more or less loosely with a fabric which is in a measure free to adjust its form to the compression of the air behind it as it revolves.
Flying Angle—The angle of incidence of the main surface of an aeroplane when in flight. See [Ground Angle].
Footpound—The amount of force required to raise one pound to a height of one foot.
Fore-and-aft—From front to rear: lengthwise: longitudinal.
Fuselage—The framework of the body of an aeroplane.