dirigible: Definition and Much More from Answers.com

Dirigibles, or motor-driven lighter-than-air craft that can be flown against the wind and steered, were first constructed in America by Caesar Spiegler. His first dirigible made its maiden flight 3 July 1878, with the great American balloonist John Wise as its pilot. Thomas Scott Baldwin built the first dirigible for the government; it was 96 feet long and had a 20-horsepower engine built by Glenn H. Curtiss. Called the SC-1, it made its first flight at Fort Myer, Virginia, in August 1908.

When the United States entered World War I, the U.S. Navy ordered sixteen dirigibles of the nonrigid type. Developed from a British model the Royal Navy used for antisubmarine patrols, U.S. Navy personnel who had been positioned in England used the English nickname for the nonrigid airship—"blimp"—and the term subsequently came into common usage in the United States. By the end of the war the navy had twenty "B-type" blimps (77,000–84,000 cubic feet; single engine) and ten "C-type" blimps (182,000 cubic feet; twin engine). In 1919 the navy airship C-5 failed in its attempt to fly across the Atlantic, but nevertheless set a 1,177-mile nonstop distance record between Montauk, New York, and Saint John's, Newfoundland, where it was destroyed in an accident.

In 1917 an army-navy joint board delegated to the navy the development of the much larger and more complex rigid airship, and in July 1919 Congress authorized the procurement of two rigid airships, one to be built in the United States and the other to be purchased abroad. The army transferred the site of Camp Kendrick, a military facility near Lakehurst, New Jersey, to the navy, which erected a huge hangar, mooring mast, and other facilities there. The Lakehurst Naval Air Station came into commission in 1921, and for the next forty-one years it was the center of American lighter-than-air aeronautics.

As the navy began the development of rigid airships, the army also began to operate dirigibles, concentrating on the semirigid type and blimps. In 1921 the army purchased the Italian semirigid T-34 airship named Roma, 412 feet long, having a gas volume of 1.2 million cubic feet, and powered by six 400-horsepower Anasaldo engines. As it had been shipped to the United States disassembled, army engineers erected it at Langley Field, Virginia, where it made its first American flight on 21 November 1921. During a trial flight with new Liberty engines on 21 February 1922 the Roma went out of control and flew into a high voltage electrical transmission line. Being inflated with hydrogen, the Roma went up in flames and crashed, killing thirty-four of the forty-five men aboard. In 1922 the army airship C-2 made the first coast-to-coast flight achieved by a lighter-than-air craft. And on 15 December 1924, a Sperry Messenger airplane equipped with a skyhook hooked onto a trapeze hung from the blimp TC-3, demonstrated the possibility of the airship's becoming an aircraft carrier. In 1925 the army procured the semirigid RS-1, fabricated by the Goodyear-Zeppelin Corporation and erected by the army's center of lighter-than-air aeronautics at Scott Field, Illinois. The RS-1 made its first flight on 9 January 1926, and although its project engineers hoped to develop it into an airplane carrier, they never conducted appropriate experiments. Shortly after its last flight on 16 October 1928, during which it sustained serious damage, the army dismantled the RS-1.

In the meantime the navy had progressed in the development of rigid airships. To begin with, the navy purchased the British airship R-38, which became the ZR-2. On 24 August 1921, the ZR-2 suffered a catastrophic structural failure during its flight trials, broke up in the air, and crashed near Hull, England, killing forty-four of the forty-nine men on board. The navy's own first rigid dirigible, the ZR-1, was 677 feet long, had a gas volume of 2.235 million cubic feet, and was powered by six 300-horsepower Packard engines. It made its first flight on 4 September 1923, and became the first rigid airship in the world to be inflated with nonflammable helium gas, following the example of the navy blimp C-7, which became the first airship of any type to use helium rather than hydrogen on 1 December 1921. (The following year, despite the greater cost of helium and its inferior lift, the navy adopted a policy of using only helium in its dirigibles, rather than highly flammable hydrogen.) On 10 October 1923, the navy formally christened the ZR-1 the U.S.S. Shenandoah. The Shenandoah made fifty-seven flights totaling 740 hours, including two coast-to-coast flights in 1924, maneuvers with the Atlantic fleet, and moorings to a floating mooring mast on the stern of the tanker U.S.S. Patoka. On 3 September 1925, the Shenandoah broke up in a violent thunder storm and crashed near Ava, Ohio, killing fourteen of the forty-three men on board.

At the end of World War I the navy was to have received two rigid dirigibles, German zeppelins, as spoils of war, but their German crews destroyed them before they could be delivered. In compensation Germany was obliged to build a new zeppelin for the navy. Germany thus constructed the LZ-126, the navy's ZR-3, best known as the U.S.S. Los Angeles. The Los Angeles was 658 feet long, had a gas volume of 2.762 million cubic feet, and relied on five 530-horsepower Maybach engines for power. It made its first flight at the Zeppelin factory in Friedrichshafen, Germany, on 27 August 1924; it made its delivery flight to the United States from 12–15 October, a transatlantic passage of eighty-one hours with thirty persons on board, the sixth transatlantic flight made by any type of aircraft. (Charles A. Lindbergh's celebrated transatlantic crossing by airplane was the seventh.) During the next eight years the Los Angeles served as a training and experimental airship for the navy, making 331 flights totaling 4,398 hours, which included two flights to Bermuda and two to Panama. The navy decommissioned it on 30 June 1932, but retained it at Lakehurst for various structural tests until scrapping it in 1940.

In 1928 the Goodyear-Zeppelin Corporation started work on two rigid airships for the navy, the ZRS-4 and ZRS-5. They were sister ships, 785 feet long, having a gas volume of 6.850 million cubic feet, and powered by eight 560-horsepower Maybach engines. At that time they were the largest airships in the world, not exceeded in size until 1936, when Germany constructed the airship Hindenburg. These airships were unique in that each could carry five Curtiss F-9C fighter planes housed in a hangar within their hulls; the airplanes were equipped with sky-hooks, and the airships could launch and retrieve planes in flight by means of a trapeze lowered from a T-shaped door in their undersides.

The ZRS-4, christened Akron, made its first flight on 25 September 1931. It made seventy-three flights totaling 1,695 hours, including two coast-to-coast flights and one to Panama. On the night of 4 April 1933, a violent electrical storm over the Atlantic caught and destroyed the Akron, which crashed at sea; of the seventy-six men on board, only three survived. The ZRS-5, christened Macon, made its first flight on 21 April 1933. It made fifty-four flights totaling 1,798 hours, including three coast-to-coast flights, and participated in several war games with the U.S. fleet. While returning from maneuvers on 12 February 1935, it suffered a minor structural failure that became uncontrollable, and the Macon crashed in the Pacific. Miraculously, only two of the eighty-three persons were killed in the accident.

The loss of the Macon ended the navy's development of the rigid airship, but the blimp remained. On the eve of World War II the navy had only a half-dozen blimps, but during the war the navy expanded its blimp forces to more than 160 airships for antisubmarine patrols. By the end of the war the United States had constructed a network of blimp bases that reached from South Weymouth, Massachusetts, to Key West, Florida, extending across the Caribbean and down the coast of South America to Rio de Janiero. In 1944 the navy flew five airships to French Morocco, where, based at Port Lyautey, they flew a low-altitude antisubmarine barrier over the Strait of Gibraltar.

The basic training airship of the war years was the L-type blimp (146 feet long, 123,000 cubic feet gas volume, two 146-horsepower Warner engines). The backbone of the antisubmarine patrol forces was the K-type blimp (251 feet, 425,000 cubic feet gas volume, two 425-horsepower Pratt & Whitney engines). During the war the United States lost only one airship to enemy action, the K-74, on 18 July 1943, after its bombs failed to release in an attack on the German submarine U-134 in the Caribbean.

After the war the navy continued its blimp development, increasing the size, lift, endurance, and versatility of its airships. In 1954 the ZPG-1-type blimp appeared (324 feet, 875,000 cubic feet, two 800-horsepower engines). The ZPG-1 was unusual in the new configuration of its tail surfaces; formerly all airship tail surfaces had been affixed to the hull at right angles to the vertical, but the ZPG-1, and all navy airships thereafter, had their tail surfaces disposed in an X configuration, 45 degrees to the vertical, which contributed to increased maneuverability.

Dirigibles have never been fast aircraft; what has recommended their use is their great lift relative to the small engine power required, and their great endurance. An airplane can be airborne for only a few hours; an airship can cruise the air for days. In 1954, for example, an American ZPG-2 stayed in the air for 200 hours. And in 1957 a ZPG-2 made a leisurely nonstop circumnavigation of the North Atlantic, 8,216 nautical miles, from South Wey-mouth, Massachusetts, to Portugal, Morocco, and the Antilles, finally landing at Key West, Florida, after being in the air for 264 hours.

The ZPG-2 that flew this nonstop double crossing of the Atlantic was 342 feet long and had a gas volume of 975,000 cubic feet. Like all other navy blimps, it was an antisubmarine aircraft. In addition, the navy modified five other ZPG-2's into ZPG-2W's that could carry an extraordinarily large air-search radar for airborne early warning duty. In 1956 the navy procured four more ZPG-3W's to carry an even larger radar. With a gas volume of 1.5 million cubic feet, the ZPG-3W was the largest non-rigid airship ever built.

By 1960 high-speed, deep-cruising nuclear submarines were rendering the blimp's antisubmarine capabilities obsolete; in addition, experts had begun to fear an attack by missiles rather than by bombers, which degraded the airship's early-warning mission. In June 1961 the navy decommissioned its blimp squadrons, and on 21 August 1962, terminated all flight operations by airships.

Since the 1920s the Goodyear Tire & Rubber Company has maintained a small fleet of advertising blimps, beginning with the Pilgrim of 1925. The Goodyear fleet reached its maximum strength in the 1930s, when it operated six airships, the Defender, Resolute, Enterprise, Reliance, Rainbow, and Ranger, all of which had been turned over to the navy as training ships by 1942. Goodyear revived its fleet after the war, but fear of the competition of television advertising caused the company to cut back its investment in the enterprise. Goodyear had only one blimp remaining when a study revealed what the American public had long known: the blimp was a unique advertising vehicle, and "blimp" had become synonymous with "Goodyear." Since 1969 three Goodyear blimps have been cruising the skies of the United States, the Columbia, Mayflower, and America, while a fourth, the Europa, operates in Western Europe. Goodyear's was the only organized airship operation in the world in the 1970s. Since then a number of other companies have built smaller blimps, including MetLife insurance company, which operates the blimps Snoopy One and Snoopy Two (decorated with images of the dog Snoopy, from the Peanuts comic strip). These flying billboards have become common sights at American sporting events, where they often provide aerial shots to television networks in exchange for free advertising.

Bibliography

Kirschner, Edwin J. The Zeppelin in the Atomic Age: The Past, Present, and Future of the Rigid Lighter-Than-Air Aircraft. Urbana: University of Illinois Press, 1957.

Robinson, Douglas H. Giants in the Sky: A History of the Rigid Airship. Seattle: University of Washington Press, 1973.

Smith, Richard K. The Airships Akron & Macon: Flying Aircraft Carriers of the United States Navy. Annapolis, Md.: U.S. Naval Institute, 1965.

Toland, John. Ships in the Sky: The Story of the Great Dirigibles. New York: Holt, 1957.

—Richard K. Smith/C. W.