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 fabric needs to be replaced. Many balloon pilots operate their envelopes at temperatures significantly less than the maximum to extend envelope fabric life. The lift generated by 100,000 ft³ (2831.7 m³) of dry air heated to various temperatures may be calculated as follows: The density of air at 20 °C, 68 °F is about 1.2 kg/m³. The total lift for a balloon of 100,000 ft³ heated to (99 °C, 210 °F) would be 1595 lb, 723.5 kg. This is just enough to generate neutral buoyancy for the total system mass (not including the heated air trapped in the envelope, of