Blimp

A blimp, or non-rigid airship, is an airship (dirigible) or barrage balloon without an internal structural framework or a keel. Unlike semi-rigid and rigid airships (e.g. Zeppelins), blimps rely on the pressure of the lifting gas (usually helium, rather than hydrogen) inside the envelope and the strength of the envelope itself to maintain their shape.Colloquially always were referred to as 'Blimps'. Over the years several explanations have been advanced about the origin of this word. The most common is that in the military vernacular the Type B was referred to as 'limp bag', which was simply abbreviated to 'blimp'. An alternative explanation is that on 5 December 1915, Commander A. D. Cunningham, R.N. of the Capel-Le-Ferne Air Ship Station, flicked the envelope of the airship SS.12 with his fingers during an inspection, which produced a sound that he mimicked and pronounced as 'blimp'; and that the word then caught on as the nickname for all small non-rigid airships.In February 1915 the need for anti-submarine patrol airships became urgent, and the Submarine Scout type was quickly improvised by hanging an obsolete B.E.2c fuselage from a spare Willows envelope; this was done by the R.N.A.S. at Kingsnorth, and on seeing the result for the first time, Horace Short, already noted for his very apt and original vocabulary, named it 'Blimp', adding, 'What else would you call it?'DIRECTV blimp Airship, Model A-170LS Video LightsignAn A-60+, the MetLife Snoopy Two A blimp, or non-rigid airship, is an airship (dirigible) or barrage balloon without an internal structural framework or a keel. Unlike semi-rigid and rigid airships (e.g. Zeppelins), blimps rely on the pressure of the lifting gas (usually helium, rather than hydrogen) inside the envelope and the strength of the envelope itself to maintain their shape. Since blimps keep their shape with internal overpressure, typically the only solid parts are the passenger car (gondola) and the tail fins. A non-rigid airship that uses heated air instead of a light gas (such as helium) as a lifting medium is called a hot-air airship (sometimes there are battens near the bow, which assist with higher forces there from a mooring attachment or from the greater aerodynamic pressures there). Volume changes of the lifting gas due to temperature changes or to changes of altitude are compensated for by pumping air into internal ballonets (air bags) to maintain the overpressure. Without sufficient overpressure, the blimp loses its ability to be steered and is slowed due to increased drag and distortion. The propeller air stream can be used to inflate the ballonets and so the hull. In some models, such as the Skyship 600, differential ballonet inflation can provide a measure of pitch trim control.