When you heat air its molecules move faster and make it bounce farther away. That makes the hot air in the balloon lighter than the air around it. So if you attach a heater under a balloon it will float up. To control how high a hot air balloon will fly you can attach sand bags to the balloon and let the sand bags go when you want to go higher. The reason why it works is because sand bags are heavy but not to heavy so the balloon can still fly.
How air planes work:
The main thing an airplane needs to fly is air pressure. When there is more air pressure on the bottom of the plane and less on the bottom that creates lift. In order for a plane to go forward (thrust) you need an engine moving a propeller or a jet engine pushing out hot air through tail pipes. The best kinds of wings are cambreeds (half of a teardrop shape) and tilted cambreeds (same thing but tilted)
In ancient Greece there were to prisoners, father and son, named Daedalus and Icarus. To escape Daedalus built wings out of wax and feathers for both of them. When they used it they were flying majestically over the sea to a land where they would not be prisoners. About half way there was a bird that challenged Icarus to see who could fly the highest they were flying as high as each one of them could go but eventually Icaruses wing melted and he drowned in the sea below.
In other Grecian myths Pegasus was a flying horse who sprung out of Medusas, one of the evil gorgons so ugly that if you look her straight in the eye you would turn to stone, head. Heracles (Hercules) was legend to have used Pegasus in many of his adventures.
In Egypt people believed that in order to get to heaven you had to fly there. Isis was one of the most powerful Egyptian gods and she had wings.
Flight in animals
Birds fly basically the same as a plane does except well for a lot of things:
Birds are living creatures
No bird... [continues]
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(2006, 10). Aero Dynamics. StudyMode.com. Retrieved 10, 2006, from http://www.studymode.com/essays/Aero-Dynamics-97652.html
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"Aero Dynamics." StudyMode.com. 10, 2006. Accessed 10, 2006. http://www.studymode.com/essays/Aero-Dynamics-97652.html.