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 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