Hot air balloon technology. The first untethered manned hot air balloon flight was performed by Jean-François Pilâtre de Rozier and François Laurent d'Arlandes on November 21, 1783, in Paris, France, in a balloon created by the Montgolfier brothers. The first hot-air balloon flown in the Americas was launched from the Walnut Street Jail in Philadelphia on January 9, 1793 by the French aeronaut Jean Pierre Blanchard. Hot air balloons that can be propelled through the air rather than simply drifting with the wind are known as thermal airships. Early unmanned hot air balloons were used in China. Zhuge Liang of the Shu Han
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