Hot air balloons are balloons that use hot air as the floating gas. At the bottom of the airbag, there is a large opening for cold air heating and a hanging basket.
The density of air decreases after heating, and when the temperature reaches 100°C, the density is about 0.95kg/m³, which is 1/1.3 of the density of air, so the lift is not high.
Modern hot air balloons have simple flight instruments, fuel tanks, burners, and other equipment installed in the basket. When lifting off from the ground, the burner is ignited, and the air is heated and filled into the airbag through the opening at the bottom. After liftoff, the burner is heated into the balloon to generate lift, and the heating time is adjusted to control the rise or fall of the balloon.
Hot air balloons were the first to appear, and nowadays, hot air balloon flights have become a favorite air sport. In addition, hot air balloons are also commonly used in aerial photography and air travel.
In the eighteenth century, the French papermakers, the Montgolfier brothers, reinvented the hot air balloon in Europe. They were inspired by scraps of paper rising in the fireplace and used paper bags to gather hot air to conduct experiments.
On June 4, 1783, the Montgolfier brothers performed a public demonstration in Lyon's Annonay Square, where a simulated balloon with a circumference of 110 feet rose and floated for 1.5 miles.
In the afternoon of November 21 of the same year, the Montgolfier brothers made the world's first manned flight in a hot air balloon at the Chateau de la Muette in Paris, flying for 25 minutes and landing near the Place d'Italie after flying halfway across Paris.
This flight preceded the Wright brothers' airplane flight by a full 120 years. In terms of inflatable balloons, the Robert brothers in France were the first to take to the skies in a balloon filled with hydrogen.
The only power of flight for hot air balloons is wind. For a balloon to fly around the world, it must choose the right speed and direction of airflow at a high altitude and move with it to complete the flight efficiently.
Just like changing planes when traveling around the world, hot air balloons need to ride on different air currents, "change air currents," when the pilot adjusts the altitude. The height of the balloon usually reaches several kilometers.
A hot air balloon usually carries enough LPG or propane to last for two hours, but several factors affect the duration of the flight, such as temperature, wind speed, basket weight (including passengers), and the specific time of the flight during the day.
The recovery of a hot air balloon requires the help of a ground crew who follows the floating balloon in a truck or minivan and arrives at the landing site in advance. A hot air balloon flight requires the services of three to four ground crews and ground radio equipment to ensure a safe, successful flight.
If there is a leak in flight, the balloon will become completely dependent on heating to maintain altitude. If the leak increases and the altitude cannot be maintained, the balloon will act as a parachute to control the rate of descent to within 5 meters per second.
If the situation continues to deteriorate, there will be enough time for the fliers to parachute out, and later it will be up to the rescuers.
