Hot Air Balloon
If you think that you can get from one place to another by flying a hot air balloon, you'll be disappointed to find out that this is a very impractical air craft. There is no possibility to steer it, and it mainly goes in the direction of the wind. However, traveling by a hot air balloon is incredibly fun, which makes it a great recreational vehicle. People who have had the chance of being aloft a hot air balloon admit to have experienced the most beautiful part of what we call flying. How does a hot air balloon work? Is it a complex technical “machine”?
Only simple physical principles are at play in the functionality of a hot air balloon. The envelope of the balloon is filled with hot air, that has a lower density than the rest of the atmosphere, and thus the balloon is able to rise. In order to maintain the temperature of the air, a device called the burner, is placed right under the open mouth of the balloon. It is up to the pilot to decide when to fire the burner and heat the balloon, depending on the altitude and the purpose of the flight as such.
Even the fuel used for a hot air balloon is adequate for our modern age; propane is the most convenient substance for the purpose, particularly since it is stored under liquid form and in very lightweight containers. The materials the hot air balloon envelope is made of also have to be adequate for this exposure to a burning propane flame. Modern balloons are usually designed from nylon gores that extend from the bottom of the envelope to its top point. Each gore consists of small panels that are very heat resistant due to their incredibly high melting temperature. A modern hot air balloon will also rely on other fire resistant materials, particularly in the area of the envelope opening.
The passenger compartment of a hot air balloon consists of a wicker basket. Wicker is preferred due to its high flexibility and lightweight. If the material were not so flexible, the passengers in the hot air balloon would feel all the impact force when landing, but under the circumstances, the shock energy is absorbed by the basket. The controls of a hot air balloon are incredibly simple, the pilot only has to open the fuel valve and fire the burner in order for the craft to rise, or to open the vent on top of the envelope and make the balloon sink.