Blimp

(aerospace engineering) A name originally applied to nonrigid, pressure-type airships, usually of small size; now applied to airships with volumes of approximately 1,500,000 cubic feet (42,000 cubic meters).

A name originally applied to nonrigid airships and usually implying small size. Early blimps contained about 100,000 ft³ (2800 m³) and were only a fraction of the size of the rigid airships of that period. The nonrigid pressure-type airship, however, did not stay small; each succeeding model built was substantially larger than its predecessor until ships with volumes of approximately 1,500,000 ft³ (42,000 m³) were operational in the U.S. Navy. With the advent of these larger sizes it appeared that the name blimp would be replaced by the more general term airship. However, the principles of construction of these ships are basically the same regardless of the size. See also Airship.

The fabric of the main envelope or pressure hull is usually made up of two or three plies of cloth impregnated with an elastomer; at least one of these plies is placed in a bias direction with respect to the others. This tends to make the fabric more resistant to shear loads and results in a stabilized structure. The materials used for the envelope must be lightweight, extremely strong, and resistant to gas diffusion. The airship envelope is a symmetrical airfoil in the form of a body of revolution, circular in cross section and elliptical along its longitudinal axis.

Inside the envelope are catenary curtains (see illustration). They support the weight of the car by distributing the loads imposed by it into the envelope fabric. This suspension system can be arranged in a number of ways, depending upon the particular airship configuration. Basically, however, they all consist of cable systems attached to the car which terminate in fabric curtains, which in turn are cemented and sewed or otherwise sealed to the envelope proper. The envelope also contains one or more air cells, fastened to the bottom or sides of the envelope, which are used to maintain the required pressure in the envelope without adding or valving of gas as the ship ascends or descends. These air cells are called ballonets and are usually made of a fabric much lighter in weight than that of the envelope, because they must merely retain gas tightness and do not have to withstand the normal envelope pressure.

Typical internal rigging of nonrigid airships.

Up until the late 1980s, the only commercial airships operating in the United States were the Goodyear Tire and Rubber Company advertising blimps of about 150,000 ft³ (4200 m³). Fundamentally, they were communications platforms used for public service where airship characteristics are superior to other forms of flight. During the 1980s, several companies other than Goodyear began to produce blimps for advertising purposes, passenger operations, and even possible military missions. Typical of these was Airship Industries of England, which produces the Skyships 500 and 600, used in Europe, the United States, Australia, and Japan, primarily as advertising billboards. In 1988, Goodyear introduced the GZ-22, the largest and most advanced blimp flying at the time, featuring a unique X-configuration tail and shrouded, swivable turboprop power plants.

n. a small airship or barrage balloon; dirigible.

(aviation) to quickly open and close a throttle, as when coming in for a landing, so that if necessary the engine will be ready for a rapid pickup.

See the Introduction, Abbreviations and Pronunciation for further details.