Aeronautics—The science of aerial navigation.
Aerofoil—A rigid structure, of large superficial area relative to its thickness, designed to obtain, when driven through the air at an angle inclined to the direction of motion, a reaction from the air approximately at right angles to its surface. Always cambered when intended to secure a reaction in one direction only. As the term "aerofoil" is hardly ever used in practical aeronautics, I have, throughout this book, used the term SURFACE, which, while academically incorrect, since it does not indicate thickness, is the term usually used to describe the cambered lifting surfaces, i.e., the "planes" or "wings," and the stabilizers and the controlling aerofoils.
Aerodrome—The name usually applied to a ground used for the practice of aviation. It really means "flying machine," but is never used in that sense nowadays.
Aeroplane—A power-driven aerofoil fitted with stabilizing and controlling surfaces.
Acceleration—The rate of change of velocity.
Angle of Incidence—The angle at which the "neutral lift line" of a surface attacks the air.
Angle of Incidence, Rigger's—The angle the chord of a surface makes with a line parallel to the axis of the propeller.
Angle of Incidence, Maximum—The greatest angle of incidence at which, for a given power, surface (including detrimental surface), and weight, horizontal flight can be maintained.
Angle of Incidence, Minimum—The smallest angle of incidence at which, for a given power, surface (including detrimental surface), and weight, horizontal flight can be maintained.
Angle of Incidence, Best Climbing—That angle of incidence at which an aeroplane ascends quickest. An angle approximately halfway between the maximum and optimum angles.