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 course) stated in the previous section. Liftoff would require a slightly greater temperature, depending on the desired rate of climb. In reality, the air contained in the envelope is not all the same temperature, as the accompanying thermal image shows, and so these calculations are based on averages. For typical atmospheric conditions (20 °C, 68 °F), a hot air balloon heated to (99 °C, 210 °F) requires about 3.91 m³ of envelope volume to lift 1 kilogram (62.5 ft³/lb). The precise amount of lift provided depends not only upon the internal temperature mentioned above, but the external temperature, altitude above