International flight 1785, when Jean-Pierre Blanchard and John Jeffries crossed the English Channel in a hot air balloon. It took more than a century for the first heavier-than-air object to repeat this process: Louis Blériot crossed the English Channel on July 25, 1909, winning a "Daily Mail" prize of £1,000. Aviation technology developed during World War I, with aviation between the World Wars seeing the development of international commercial flights. There was a combination of aircraft types which included airships and airplanes. The first airline to operate international flights was Chalk's Ocean Airways, established 1917, which operated scheduled seaplane services from Florida
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