Span (Spread)—The dimension of a surface across the air stream.
Streamline—Exposing as little surface as possible to offer resistance to air.
Skids—In connection with model aëroplanes, steel wires or strips of bamboo allowed to extend below the frame to protect the model in landing and to permit its rising off the ground or ice.
S or Motor Hooks—A piece of wire bent in a double hook to resemble the letter “S.” One end to be attached to the frame hook, the other serving as accommodation for the rubber strands.
T
Tail—The plane or planes, both horizontal and vertical, carried behind the main planes.
Tandem—An arrangement of two planes one behind the other.
Thrust—The power exerted by the propeller of an aëroplane.
Tension—The power exerted by twisted strands of rubber in unwinding.
Tractor—An aëroplane with the propeller situated before the main supporting surfaces.