A hot air balloon is an aircraft that relies on buoyancy and is lighter than air. The upper part of the balloon is in the shape of a large balloon, and the lower part is a gondola.

The inside of the balloon heats the air, making it less dense than the cooler air outside, which creates buoyancy to displace the whole.

A gondola carries passengers and a heat source, which is usually an open flame. Modern hot air balloons are made of nylon fabric with a refractory opening at the bottom.

The world's first hot air balloon was created by the Montgolfier brothers of France. They were inspired by the phenomenon that scraps of paper continued to rise after burning in a stove.

After a series of experiments and improvements, they invented the earliest hot air balloon. In 1783, they created the first primitive hot air balloon, which flew manned over Paris for 25 minutes, realizing the dream of human beings to fly in the blue sky for the first time.

Hot air balloons are based on a basic scientific principle: hot air is lighter than cold air. Because the mass per unit volume of hot air is small, 1 cubic decimeter of air weighs about 1 gram. If it is heated to 37.8 degrees Celsius, the weight of the same volume of air will be reduced by about 0.25 grams.

Therefore, a cubic decimeter of air in a hot air balloon can lift 0.25 grams of objects, which is not sufficient. That is why hot air balloons are so large.

To lift an object of 454 kg, approximately 1840 cubic meters of hot air are needed! So, to make a hot air balloon go up, the pilot needs to keep heating the air. When the air in the balloon cools, the pilot can reheat the air by lighting the burners.

Hot air balloons are safe. The only driving force for a hot air balloon is the wind. It is not really "piloted" but goes with the wind. Therefore, the pilot must choose the right high airflow with the proper speed and direction to move with it, to effectively complete the flight.

The International Aeronautical Federation once listed hot air balloons as the safest aircraft. Judging from the data alone, the safety factor of hot air balloons is quite high. It is understood that there are about 20,000 hot air balloons in the world.

In developed countries such as Europe and the United States, hot air ballooning is a popular sport, and there are hot air balloon competitions or activities almost every day.

With the development of hot air balloon sports, technological elements are constantly being added to hot air balloon sports. In addition to being a recreational activity, hot air balloons have other practical uses.

For example, hot air balloons can be used for scientific research and weather observations. They can carry various equipment and instruments and conduct observations and experiments at high altitudes.

Hot air balloons are also widely used in tourism and become a unique way of traveling. Tourists can take a hot air balloon, overlook the beautiful scenery, and experience different cultures and geographical environments. In some countries, hot air balloons are also used to promote tourism and attract more tourists to visit.

Furthermore, a group of pilots and teams with outstanding achievements have emerged in hot air balloon sports. They have demonstrated superb technology and innovative spirit in hot air balloon competitions.

For example, some pilots have used hot air balloon control technology to create multiple world records, including crossing the Atlantic Ocean and crossing the polar regions.

Overall, hot air balloons not only bring joy and excitement to people but also have practical applications in scientific research and tourism. With the continuous development of technology and the increasing popularity of hot air balloon sports, we can expect even more exciting achievements and breakthroughs in this field in the future.