History of transport balloons filled with hot air were used in the first half of the 19th century and saw considerable action in several mid-century wars, most notably the American Civil War, where balloons provided observation during the Siege of Petersburg. Apart from some scattered reference in ancient and medieval records, resting on slender evidence and in need of interpretation, the earliest clearly verifiable human flight took place in Paris in 1783, when Jean-François Pilâtre de Rozier and François Laurent d'Arlandes went in a hot air balloon invented by the Montgolfier brothers. The Wright brothers made the first sustained, controlled and powered heavier-than-air
Hot air balloon indicators would be useless) and direction. The combined mass of an average system can be calculated as follows: using a density of 0.9486 kg/m³ for dry air heated to 210 °F (99 °C). Increasing the air temperature inside the envelope makes it less dense than the surrounding (ambient) air. The balloon floats because of the buoyant force exerted on it. This force is the same force that acts on objects when they are in water and is described by Archimedes' principle. The amount of lift (or buoyancy) provided by a hot air balloon depends primarily upon the difference between the