R
Radial Spoke—A wire spoke extending from the hub of an alighting wheel straight outward from the centre to the rim of the wheel. See [Tangent Spoke].
Rarefaction Side—A correct term for the incorrect “vacuum side,” so-called. The side opposite the compression side: the forward side of a revolving propeller blade, or the upper side of a flying surface, or the side of a rudder-surface turned away from the wind.
Reactive Stratum—The layer of compressed air beneath a moving aeroplane surface, or behind a moving propeller blade.
Rib—The smaller construction members used in building up surfaces. Generally they run fore-and-aft, crossing the spars or wing-bars at right angles, and they are bent to form the curve of the wings or planes.
Rising Angle—Technically, the steepest angle at which any given aeroplane will rise into the air.
Rudder—A movable surface by which the aeronaut is enabled to steer his craft in a desired direction. See [Horizontal Rudder] and [Vertical Rudder].
Runner—A construction similar to the runners of a sleigh, used for alighting on some machines, instead of the wheel alighting gear; a skid.