A blimp is a kind of airship, or dirigible, that is powered, steerable, and lighter than air. It has no internal structural framework or keel. The pressurized gas used to inflate such a vehicle and the strength of the envelope itself maintain its shape.
Zeppelins, on the other hand, have rigid frames that retain their shape whether or not they are filled with gas. A hot air balloon is not technically an airship because it is not steered by a driver, but relies on the wind to take it to the desired destination.
Blimps are the most commonly built airships because they are relatively easy to build and easy to transport when deflated. However, because of the unstable hull, their size is limited. A blimp with too long a hull may kink in the middle when the overpressure is insufficient or when maneuvered too fast. This led to the development of semi-rigid and rigid airships.
“Overpressure” here is defined as “in excess of normal atmospheric pressure,” meaning that the internal gas must be at a high enough pressure to keep the airship inflated.
The most common theory for the origin of the word “blimp” is that it came to be used during World War I when the British were experimenting with lighter-than-air craft. The initial non-rigid aircraft was called the A-limp; and a second version called the B-limp was deemed more satisfactory.
Another theory is that in 1915, during an inspection, a naval officer flicked the envelope of an airship with his fingers, which produced a sound that he pronounced as ‘blimp’; and that the word caught on as the nickname for all small non-rigid airships. The “B-limp” explanation sounds a lot more likely to me.
As to history, Jacques and Joseph Montgolfier of France invented the hot-air balloon in 1783 and sent one to an altitude of 6,000 ft. Count Ferdinand von Zeppelin of Germany invented the first rigid airship in 1900. It carried five people to an altitude of 1,300 ft and flew a distance of 3.75 mi. Several models of Zeppelins were built in the early 1900s. The most famous was the Hindenburg, destroyed by a fire in 1937 while landing in New Jersey.
In 1925, Goodyear Tire & Rubber Company began building blimps. These were used for advertising and military purposes (such as surveillance and anti-submarine warfare) in World War II. Today, blimps are used mainly for advertising.
Then there’s that other use for “blimp,” to describe a person of generous proportions. But how inaccurate! After all, isn’t a blimp lighter than air?