A fixed-wing aircraft with two sets of wings mounted, generally, one above the other.

External bracing wires, usually of streamline section, which support the wings when the aircraft is on the ground.

Method of lateral control adopted by Wright brothers and many early builders/designers, in which a flexible wing is twisted (warped) to provide roll control as with ailerons.

The maximum altitude above sea level at which a heavier-than-air craft can be maintained in level flight.

(I) Air cushion landing system, or (II) automatic carrier landing system.

Automatic Direction Finding; utilizing an automated radio direction finding (RDF) technique.

Voluntary maneuvers, initiated by a pilot, other than those for conventional flight.

An area set aside for the operation of aircraft.

The branch of fluid mechanics dealing with air (gaseous) motion, and the reactions of a body moving within that air.

A body or structure shaped to obtain an aerodynamic reaction when travelling through the air.