Struts.—The pieces which hold together longitudinally the main frame beams.
Superposed.—Placed one over another.
Surface Area.—The amount of cloth-covered supporting surface which furnishes the sustaining quality.
Sustentation.—Suspension in the air. Power of sustentation; the quality of sustaining a weight in the air.
Triplane.—Flying machine with three surface planes.
Thrust of Propeller.—Power with which the blades displace the air.
Width.—The distance from the front to the rear edge of a flying machine.
Wind Pressure.—The force exerted by the wind when a body is moving against it. There is always more or less wind pressure, even in a calm.
Wing Tips.—The extreme ends of the main surface planes. Sometimes these are movable parts of the main planes, and sometimes separate auxiliary planes.