The Aeroplane Speaks

by H. Barber

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.

Angle of Incidence, Optimum—The angle of incidence at which the lift-drift ratio is the highest.

Angle, Gliding—The angle between the horizontal and the path along which an aeroplane at normal flying speed, but not under engine power, descends in still air.

Angle, Dihedral—The angle between two planes.

Angle, Lateral Dihedral—The lifting surface of an aeroplane is said to be at a lateral dihedral angle when it is inclined upward towards its wing-tips.

Angle, Longitudinal Dihedral—The main surface and tail surface are said to be at a longitudinal dihedral angle when the projections of their neutral lift lines meet and produce an angle above them.