4763 x 3820 px | 40,3 x 32,3 cm | 15,9 x 12,7 inches | 300dpi
Altre informazioni:
A balloon is a type of aircraft that remains aloft due to its buoyancy. A balloon travels by moving with the wind. It is distinct from an airship, which is a buoyant aircraft that can be propelled through the air in a controlled manner. There are three main types of balloon aircraft: Hot air balloons obtain their buoyancy by heating the air inside the balloon. They are the most common type of balloon aircraft. "Hot air balloon" is sometimes used incorrectly to denote any balloon that carries people. Gas balloons are inflated with a gas of lower molecular weight than the ambient atmosphere. Most gas balloons operate with the internal pressure of the gas being the same as the pressure of the surrounding atmosphere. There is a type of gas balloon, called a superpressure balloon, that can operate with the lifting gas at pressure that exceeds the pressure of the surrounding air, with the objective of limiting or eliminating the loss of gas from day-time heating. Gas balloons are filled with gases such as: hydrogen - not widely used for aircraft since the Hindenburg disaster because of high flammability (except for some sport balloons as well as nearly all unmanned scientific and weather balloons). helium - the gas used today for all airships and most manned balloons. ammonia - used infrequently due to its caustic qualities and limited lift. coal gas - used in the early days of ballooning; it is highly flammable. Rozière balloons use both heated and unheated lifting gases. The most common modern use of this type of balloon is for long-distance record flights such as the recent circumnavigations. The hot air balloon Kongming lantern was developed for military communications around the second or third century AD in China. It is thought that some ancient civilizations may have developed manned hot air balloon flight. For example, the Nazca lines (which are best seen from the air) allegedly presuppose some form of manned flight, such as a balloon.
