Hot air balloon principle

The basic principle of hot air balloon is that it expands when heated and contracts when cooled. When air expands when heated, its specific gravity will become lighter and rise.

A hot air balloon is mainly composed of a huge airbag, a hanging basket for carrying people or articles and a burner for heating air.

The burner injects the air heated by combustion into the airbag from the port at the lower part of the airbag, and the hot air gathers in the airbag to generate lift force, so that the balloon lifts the hanging basket and lifts off together.

At present, balloons are usually made of flame retardant reinforced nylon or polyester. The balloon is thin and light, but its tensile strength is very good and it is airtight.

The hanging basket is made of rattan (most of our country adopts materials imported from Southeast Asia), which can play a buffering role when landing.

Four special liquefied gas bottles for hot air balloons and instruments were placed at the four corners of the hanging basket. The hanging basket is also equipped with flying instruments such as thermometer, altimeter and lifting platform.

The burner is the heart of a hot air balloon, and its burning energy is 150 times that of ordinary domestic gas stoves. When the main burner is ignited, the flame is 2-3 meters high and makes a loud noise. Ignition burner is the fire of the main burner. Always keep the fire, it won't be blown out by the wind. In addition, there are two sets of combustion systems on the hot air balloon to prevent failures in the air.

Hot air balloons generally use propane or liquefied petroleum gas, and gas cylinders are fixed in hanging baskets. A hot air balloon can carry 80 kilograms of liquid fuel.

A hot air balloon has no power system and travels downwind in the air. However, because the wind has different directions and speeds at different altitudes, pilots can choose the appropriate altitude according to the direction needed for flight. The only flight power of a hot air balloon is the wind. One or two hours before sunrise or sunset in a day is the best time for hot air balloon flight, because it is usually calm and the airflow is stable. Strong winds and fog are not conducive to the flight of hot air balloons; Keep a safe height when flying over high-voltage lines, tall buildings, livestock farms and villages. A hot air balloon usually carries enough liquefied petroleum gas or propane to fly for about two hours, but some factors will also affect the flight duration, such as temperature, wind speed, hanging basket weight and specific flight time. According to experts, because the hot air balloon launch is complicated, it usually needs the joint efforts of several people to complete it. Spread the balloon on the ground first, then connect it with the hanging basket put aside, and blow air into the balloon with a small blower to make it expand little by little. When it is fully unfolded, it will start to ignite. Light the fire and heat the air in the balloon. The hot air makes the balloon rise to a position perpendicular to the hanging basket. Add a few fires and the balloon will take off. Flight principle of hot air balloon

The principle of hot air balloon flight is that the density of hot air is less than that of cold air, and the same volume of hot air is lighter than that of cold air, resulting in buoyancy. By heating the air in the balloon to make it lighter and generate buoyancy, the balloon can be lifted off under load. By turning on the interval of the combustion switch, the temperature (gas density) of the balloon is adjusted to control the rise and fall of the hot air balloon; Use the wind direction of different height layers to control and adjust their own direction; A hot air balloon can't change its direction actively, and its flight speed is the same as the wind speed.

The average density of real hot air balloon is less than that of air because of the low density of hot air.

The buoyancy of a hot air balloon is greater than its own gravity.

So it went up.

I did the simplest thing when I was a child.

A portable plastic bag

A few ropes

A candle head

It's like tying a big hot air balloon

When air is heated, its density becomes smaller, thus gaining buoyancy.

It is generally a heat-resistant composite material.

Small ones don't care about designing patterns.

As the temperature rises, the volume of air becomes larger. Air with high temperature is lighter than air with low temperature, so air with high temperature floats on it. Hot air balloons are made by using this property of air.