at the very start, the first balloonists burnt materials onboard the balloon to generate heat to propel the envelope into the air. Theory then became obsolete as gas and helium designs were introduced as it was considered safer and more reliable than flying with an open flame.
When air is blown between two balloons, the air flow from the blower creates a low-pressure area between the balloons. This low pressure effectively pulls the balloons towards each other. The Bernoulli principle, which states that moving air has lower pressure, helps explain this phenomenon.
olden day hot air balloons were made of heavy cotton or linen fabric and carried animals, while modern hot air balloons are made out of heat resistant nylon and carried people hope this helps if this isn't what you're looking for here are some other websites to try http://www.hotairballooning.com/faq/entry/how_do_balloons-fly-29.html or http://www.eballoon.org/history/history-of-ballooning.html these websites are really useful for projects :D
A water balloon is filled with water, and other balloons are filled with air or helium.
Helium is lighter than air, so a balloon filled with helium will float. In contrast, air-filled balloons will sink because the density of air is greater than that of helium. Additionally, helium balloons will deflate faster than air-filled balloons due to its smaller molecular size.
Nylon
Hot air balloons rely on the temperature difference between the air inside and outside the balloon to generate lift. As you ascend, the temperature of the air outside the balloon decreases, reducing the lift. At higher altitudes, the balloon would need a larger temperature difference to stay afloat, which is difficult to achieve with a burner.
This relationship between the temperature and volume of a gas, which became known as Charles' law, provides an explanation of how hot-air balloons work
If you blow between them, you decrease the pressure of the air between the balloons. The air around them, which has greater pressure, will force them to approach each other.
They draw closer together. The high speed air causes a partial vacuum, the relative pressure on the outside of the balloons pushes them closer together. This is principle by which an aeroplane wing works. It is called the Bernoulli principle.
old markets not well roofed but modern market are air conditioned
old markets not well roofed but modern market are air conditioned
old markets not well roofed but modern market are air conditioned