Wednesday, July 22, 2009
The hot air balloon is the oldest successful human-carrying flight technology and is a subset of balloon aircraft. On November 21, 1783, in Paris, France, the first manned flight was made by Jean-François Pilâtre de Rozier and François Laurent d'Arlandes in a hot air balloon created by the Montgolfier brothers. Recently, balloon envelopes have been made in all kinds of shapes, such as hot dogs, rocket ships, and the shapes of commercial products. Hot air balloons that can be propelled through the air rather than just being pushed along by the wind are known as airships or, more specifically, thermal airships.
A hot air balloon consists of a bag called the envelope that is capable of containing heated air. Suspended beneath is the gondola or wicker basket (in some long-distance or high-altitude balloons, a capsule) which carries the passengers and (usually) a source of heat, usually an open flame. The heated air inside the envelope makes it buoyant since it has a lower density than the relatively cold air outside the envelope. Unlike gas balloons, the envelope does not have to be sealed at the bottom since the air near the bottom of the envelope is at the same pressure as the surrounding air. In today's sport balloons the envelope is generally made from nylon fabric and the mouth of the balloon (closest to the burner flame) is made from fire resistant material such as Nomex.
Unmanned hot air balloons are popular in Chinese history. Zhuge Liang of the Shu Han kingdom, in the Three Kingdoms era (220–80 AD) used airborne lanterns for military signaling. These lanterns are known as Kongming lanterns (孔明灯). There is also some speculation that hot air balloons could have been used by people of the Nazca culture of Peru some 1500 years ago, as a tool for designing the famous Nazca ground figures and lines. The first documented balloon flight in Europe was by the Portuguese priest Bartolomeu de Gusmão. On August 8, 1709, in Lisbon, Bartolomeu de Gusmão managed to lift a small balloon made of paper full of hot air about 4 meters in front of king John V and the Portuguese court.
The first clearly recorded instance of a balloon carrying passengers used hot air to generate buoyancy and was built by the brothers Joseph-Michel and Jacques-Etienne Montgolfier in Annonay, France. After experimenting with unmanned balloons and flights with animals, the first tethered balloon flight with humans on board took place on October 19, 1783 with the scientist Jean-François Pilâtre de Rozier, the manufacture manager, Jean-Baptiste Réveillon and Giroud de Villette, at the Folie Titon in Paris. The first free flight with human passengers was on November 21, 1783. King Louis XVI had originally decreed that condemned criminals would be the first pilots, but de Rozier, along with Marquis Francois d'Arlandes, successfully petitioned for the honor.
Modern hot air balloons, with an onboard heat source, were pioneered by Ed Yost, beginning in the 1950s; his work resulted in his first successful flight, on October 22, 1960. The first modern-day hot air balloon to be built in the United Kingdom (UK) was the Bristol Belle in 1967. Today, hot air balloons are used primarily for recreation.
Hot air balloons are able to fly to extremely high altitudes. On November 26, 2005, Vijaypat Singhania set the world altitude record for highest hot air balloon flight, reaching 21,027 meters (68,986 feet). He took off from downtown Bombay, India, and landed 240 kilometers (149 miles) south in Panchale. The previous record of 19,811 m (64,997 ft) had been set by Per Lindstrand on June 6, 1988 in Plano, Texas. As with all unpressurized aircraft, oxygen is needed for all crew and passengers on any flight that exceeds an altitude of about 15,000 ft (4,572 m).
On January 15, 1991, the Virgin Pacific Flyer balloon completed the longest flight in a hot air balloon when Per Lindstrand (born in Sweden, but resident in the UK) and Richard Branson of the UK flew 7,671.91 km (4,767.10 mi) from Japan to Northern Canada. With a volume of 74 thousand cubic meters (2.6 million cubic feet), the balloon envelope was the largest ever built for a hot air craft. Designed to fly in the trans-oceanic jet streams the Pacific Flyer recorded the highest ground speed for a manned balloon at 245 mph (394 km/h). The longest duration hot air balloon flight ever made is 50 hours and 38 minutes made by Michio Kanda and Hirosuke Tekezawa of Japan on January 2, 1997