balloon
balloon lighter-than-air craft without a propulsion system, lifted by inflation of one or more containers with a gas lighter than air or with heated air. During flight, altitude may be gained by discarding ballast (e.g., bags of sand) and may be lost by releasing some of the lifting gas from its container.
Although interest in such a craft dates from the 13th cent., the balloon was not actually invented until the late 18th cent., when two French brothers, Joseph and Jacques Étienne Montgolfier , experimented with inverted paper and cloth bags filled with heated air and, in 1783, caused a linen bag about 100 ft (30 m) in diameter to rise in the air. In the same year the Frenchmen Pilâtre de Rozier and the marquis d'Arlandes made one of the first balloon ascents by human beings, rising in a hot-air-filled captive balloon (i.e., one made fast by a mooring cable to prevent free flight) to a height of 84 ft (26 m). In 1766 the English scientist Henry Cavendish had shown that hydrogen was seven times lighter than air, and the usefulness of this gas in balloon ascension was demonstrated in Dec., 1783, by J. A. C. Charles of France, who with his associates successfully ascended in a hydrogen-filled balloon and traveled 27 mi (43 km) from the starting point.
The first ascent in England was made by James Tytler, a Scottish writer, in 1784, and in 1793 the French balloonist J. P. Blanchard made an ascent at Philadelphia. Blanchard, with Dr. John Jeffries, an American physician, also made the first sea voyage by balloon, crossing the English Channel in 1784. Among the noted balloon voyages of the 19th cent. was that made by the Swedish engineer S. A. Andrée , who, in 1897, attempted unsuccessfully to reach the North Pole by balloon. In the American Civil War and World War I, captive balloons were used to observe troop movements and to direct gunfire. Captive balloons, called barrage balloons, were used as obstacles against low-flying aircraft in World War II.
The helplessness of the free balloon in controlling direction led to the development of the dirigible balloon (see airship ). In 1932 the Swiss physicist Auguste Piccard , one of the major figures in 20th-century ballooning, ascended in a balloon with a sealed spherical gondola to a height of 55,500 ft (17,000 m); since then manned balloons have reached heights of 100,000 ft (30,500 m) and unmanned balloons have exceeded 140,000 ft (42,500 m). The Americans Ben Abruzzo, Maxie Anderson, and Larry Newman made the first transatlantic crossing in 1978, and in 1981 Abruzzo, Newman, Rocky Aoki, and Ron Clark crossed the Pacific. In Mar., 1999, Jacques Piccard, Auguste's grandson, and Briton Brian Jones made the first nonstop balloon flight around the world; the American Steve Fossett completed the first nonstop solo circumnavigation in July, 2002. Today high-altitude hydrogen balloons carry aloft radios and other instruments, used to transmit meteorological readings or to take photographs free from atmospheric distortion.
In contemporary sporting balloons, which use air heated by a small gas-fired burner, altitude is controlled by varying the temperature of the heated air. Hot-air balloons represent the fastest-growing segment of ballooning. Gas bags made with space-age materials are more durable and weigh far less than the traditional silk; heaters have similarly become more efficient. While ballooning remains dangerous, the hot-air balloon's slow response time offers a unique sensation of effortless motion through the atmosphere.
Bibliography: See A. Hildebrandt, Balloons and Airships (1976); J. P. Jackson and R. J. Dichtl, The Science and Art of Hot Air Ballooning (1977); B. Piccard and B. Jones, Around the World in 20 Days (1999).
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