Jean-Pierre Blanchard Lunardi flew from Moorfields to Ware on 15 September 1784. Blanchard's propulsion mechanisms – flapping wings and a windmill – again proved ineffective, but the balloon flew some 115 km from the military academy in Chelsea, landing in Sunbury and then taking off again to end in Romsey. Blanchard took a second flight on 30 November 1784, taking off with an American, Dr John Jeffries, from the Rhedarium behind Green Street Mayfair, London to Ingress in Kent. A third flight, again with Jeffries, was the first flight over the English Channel, taking about 2½ hours to travel from England to
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