1783, in a small village in France, there lived two brothers who were full of fantasy and brave in practice. Their names are Joseph Montgomery and Essien Montgomery. They made a big bag of paper, about 10 meter in diameter, ready to make a hot air balloon and let it go to the sky.
One day in June, the two brothers released a public performance preview. At that time, it was so novel and unpredictable that it attracted a large number of people. On the day of the performance, people around the small village got up early in the morning and rushed to this unknown village. People saw a pile of semi-wet rags and straw burning in a clearing in the village. Above the slow burning flame, there is a huge paper bag tied with a rope. Soon the paper bag was full of hot air, and the hot air was getting more and more. Until this hot air balloon needs eight people to get it. At this time, the rope tied to the balloon was cut and the hot air balloon rose. To this end, the visiting crowd cheered. The balloon rose to a height of several hundred meters.
After that, with the cooling of the hot air inside, the balloon gradually landed. Due to the influence of the breeze, the balloon fell about 1 km from the rising place.
The experiment of this balloon attracted the attention of all parties, and the news soon reached the king. The king ordered the Montgomery brothers to repeat the performance in front of him. According to this will, the Mont Gofel couple raised another hot air balloon in the garden of the King of Versailles on September 19 of that year. Compared with the first time, this balloon is bigger and carries three passengers: sheep, chicken and duck. When the hot air in the hot air balloon gradually cooled down, the balloon fell into a nearby field. A farmer who is working in the field is very afraid of these "uninvited guests" falling from the sky, but these three animal tourists are carefree. The Montgomery brothers are very happy about this. Because, before that, no one knew whether the air in the air was suitable for breathing. Now that three animal travelers have safely returned to the ground, the answer is yes.
Animals can go to heaven, which aroused people's interest in heaven. A month later, a brave young man Luo sat on a balloon tied firmly to the ground with a long rope and stayed in the air more than 30 meters above the ground for 25 minutes. He was very excited when he returned to the ground. He told everyone that in this experiment, he enjoyed the beautiful rural scenery to his heart's content and was really relaxed and happy. Another month later, Rozier and Arendt began to fly freely in the air for the first time in a hot air balloon. Before the flight, friends came to say goodbye to them in tears, as if their free flight was coming to an end. The hot air balloon carried two brave men to hundreds of meters in the air, drifted across Paris with the wind, and finally returned to the ground safely. What greeted them was no longer the tears of friends, but joy and praise ... the desire of human beings to fly in the air has come true! With the birth of hot air balloon, this beautiful wish came true.
Why can a hot air balloon rise to take people flying? The reason is this: the first balloon with a man flying freely in the air was made according to Archimedes principle applicable to gas, and the proportion of hot air was smaller than that of cold air. The whole balloon is very large, and it is "immersed" in the fluid-air. At this time, the buoyancy of the balloon is equal to the product of the volume of the balloon (including the hanging basket) and the specific gravity of the cold air, that is, the weight of the gas discharged from the balloon; This value is greater than the weight of the balloon because the specific gravity of hot air is not as important as that of cold air. In this way, the hot air balloon rises under the action of buoyancy. With the breeze in the air, hot air balloons can drift.
Balloons like this have been used as military signals in our country for a long time. In the 2nd century BC, Emperor Wu of the Han Dynasty made thin-shell lanterns out of light materials, lit candles under them, filled the thin-shell lanterns with hot air, and the lanterns soared. This is the earliest balloon in China. It can float in the air without wings or mechanical help, and it is very light. So the bigger the volume, the greater the bearing capacity of the balloon. Because the balloon has incomparable advantages over other aircraft, people have not abandoned it until today.
The meaning of life is not to enjoy, but to explore, and people's longing for heaven is not just to enjoy the natural scenery. Therefore, balloons are not only used as flying machines for people to travel, but also used in military, scientific research and many other undertakings. 187 1 year, someone in France took a photo of Paris from the air with a hot air balloon. This incident is a great encouragement to people. During the First World War, some countries used balloons to take pictures from the air to spy on each other's military arrangements and trends. Balloons can not only carry people, but also be used for observation. Due to the stable attitude of the balloon in the upper atmosphere, the stay time can be as long as dozens of hours or even half a year. Let the balloon carry various scientific instruments, and you can get some upper atmosphere or other scientific information.
According to relevant data, the height of manned balloon in 1966 reached more than 37,000m. The height of unmanned balloon 1972 reached 510000m. In recent years, some people abroad have used balloons to fly to the whole country, and some people have used balloons to fly to the world! Many scientists have also put forward the bold idea of using the buoyancy of air to build giant balloons. There are comfortable bedrooms, restaurants and clubs above the balloon, as well as various science laboratories. Let it float 30 kilometers above our heads and make this giant balloon an air science city.