Hot Air Balloons
Real hot air balloons allow people to break the law of gravity, if only for a few hours, to soar quietly over the land for a bird's eye view of city and countryside. A hot air balloon is a lighter-than-air aircraft which uses the basic scientific principle that warm air rises in cooler air. Hot air has less mass than cool air. When hot air fills the balloon it floats or suspends in mid air. A hot air balloon large enough to carry a basket full of people into the air has to be very large because in order to lift at least 1,000 lbs the balloon needs to be filled with 65,000 cubic feet of hot air.
The largest part of a hot air balloon is called an envelope. The envelope is the part of the aircraft that contains the heated air necessary to keep the craft afloat. Suspended beneath the envelope is the gondola or wicker basket. Passengers ride in the basket portion. The balloon pilot controls the source of heat, usually open flame from a liquid propane tank. The balloon design can allow the pilot to control altitude and vertical speed but hot air balloon are not practical for travel as they can only move as fast as the wind blows and can't be steered in any defined direction.
The Sky lantern, or Chinese lantern is the oldest form of hot air balloon. The unmanned lanterns were used during the Three Kingdoms era (220–280 AD) as airborne lanterns to send signals to military leaders and troops.
Hot air balloon festivals and sporting events attract millions of spectators every year when thousands of balloon take to the skies. Enthusiasts claim balloon travel is both an exhilarating and serene experience.