How hot air balloons work, how hot air balloons work

The force that causes a "hot air balloon" to rise and fall can only be explained by two principles.

1. Principles of fluid dynamics:

From the "fire windmill" experiment, it is not difficult to see that there is a rising air flow above the fire. It was this air flow that turned the "fire windmill" around. We did not visit to do an experiment, using transparent plastic film to make a Kong Ming lantern with a diameter of about 600mm and a height of about 750mm, lighting an alcohol lamp at the opening directly below the Kong Ming lantern, lighting a few mosquito coils around the alcohol lamp, and injecting white smoke into the Kong Ming lantern, it can be seen that the smoke forms a convection current in the Kong Ming lantern (as shown in the figure), and the smoke directly above the flame flows upwards at a greater speed, and the larger the flame, the greater the flow velocity.

Away from the surrounding area of the flame, the speed of smoke turbulence is less. It can be seen that the updraft has a hydrodynamic effect on the top of the Kong Ming lantern. The magnitude of this force is related to the mass of the fluid and the velocity of the flow, which in turn is related to the magnitude of the flame (the hot air balloon uses the size of the fire to control the rise and fall).

Experiments have shown that there is gas flowing out of the vicinity of the lantern, but it is found that there is also air flowing into the lantern under the flame, which not only replenishes the outflow of air, but also replenishes the oxygen required for the flame to burn.

2. Principle of Molecular Momentum:

The momentum of the motion of the molecule p=mv, the force exerted on the object f=(p1-p0) t. The magnitude of the applied force is related to the impulse (momentum difference) per unit time, and the greater the impulse, the greater the acting force. The magnitude of momentum is in turn related to the mass of the molecule and the velocity of the molecule.

The greater the mass of the molecule, the greater the velocity of motion, and the greater the momentum of the molecule. It can be seen that when there is a certain amount of carbon dioxide in the Kong Ming lantern, the molecular weight of carbon dioxide is larger than the average molecular weight of air, so the lifting force will increase significantly.

The "buoyancy" in Archimedes' principle is generated by the pressure difference between the upper and lower surfaces of an object immersed in a stationary fluid, which belongs to hydrostatic mechanics. The principle of lifting and lowering of the "hot air balloon" and the "Kong Ming lantern" should be explained by "hydrodynamics".

The air is heated to expand and its density decreases, so the buoyancy of the air increases.

It is true that the above says that the air is heated to expand and the density decreases, but it is not correct to say that the buoyancy of the air is increased, the buoyancy does not change, the gravity is smaller, and the buoyancy is greater than the gravity, so it floats up.

Balloon. The basic principle is thermal expansion and cold contraction.

When the air expands when heated, the specific gravity becomes lighter and rises upwards. Hot air balloons are the use of heated air or certain gases such as hydrogen or helium that are less dense than the air outside the balloon.

to create buoyancy flight. The hot air balloon mainly adjusts the temperature of the air in the airbag through its own on-board heater, so as to achieve the purpose of controlling the balloon lifting.

The principle of balloon lift-off is simply as follows: the air inside the balloon becomes less dense when heated, and the mass is lighter than the same volume of cold air outside the balloon, so the balloon generates buoyancy and lifts off.

A hot air balloon mainly consists of a huge airbag and a gondola for carrying people or items, as well as a burner for heating the air. The burner sprays the heated air into the airbag through the port at the lower part of the airbag, and the hot air gathers in the airbag to generate lift, so that the balloon can be dragged up and lifted into the air together.

The best time of day is when the sun is just rising or an hour or two before the sun goes down because the winds are usually calm and the airflow is steady. Strong winds and fog.

Not conducive to the flight of hot air balloons. According to the regulations, the wind speed is less than 6 meters and seconds, and the visibility is there.

It is more than one kilometer, and there is no precipitation in the flight airspace, so it can fly freely.

Hot air balloons do not have a power system.

In the air is to follow the wind. However, since the wind has different directions and speeds at different altitudes, the pilot can choose the appropriate altitude according to the direction required for the flight.

Using density, i.e., the density of hot air is less than that of cold air, and the gas with less density always floats on top of the gas with higher density. When the density of hot air inside the sphere is less than the density of cold air outside, the hot air balloon rises. When the density of hot air in the sphere is greater than the density of cold air outside, the hot air balloon will be ready to roll down in spring.

Using density, i.e., the density of hot air is less than that of cold air, and gases with less density always float slip on top of gases with higher density. When the density of hot air inside the sphere is less than the density of cold air outside, the hot air balloon rises. When the density of hot air inside the sphere is greater than the density of cold air outside, the hot air balloon descends.

A hot air balloon is an early aviation tool that uses the principle of heating gas to create buoyancy. Its working principle mainly includes several aspects of hunger.

The shape and structure of a hot air balloon.

Hot air balloons usually consist of a huge spherical air bag and a basket hanging downward. The gas bag is generally composed of durable polyester cloth and nylon, which can withstand high temperature and high pressure gas. The basket, made of aluminium alloy, is suspended under the air bag and is used to carry the passengers and equipment of the hot air balloon.

Airbags for the manufacture of hot air balloons.

Airbags are the most basic part of a hot air balloon. The original hot air balloons were made of lightweight materials such as yarn, cotton, or silk. Modern hot air balloons are made of materials such as nylon or polyester that are resistant to high temperatures.

The size and shape of the air bag affects the air lift of the hot air balloon. To ensure safety and lift balance, the design and construction of hot air balloon airbags is critical.

Gas to fill a hot air balloon.

Hot air balloons need to be filled with enough gas to create buoyancy. The most common method is to use liquefied petroleum gas as fuel, which is heated in a burner at the bottom of the air bag to make the fuel burn, generating a large amount of heat, which heats the gas and causes it to expand. In general, a hot air balloon needs to be filled with about 75,000 cubic feet of gas in an air bag before it can take off.

Lift and descent of a hot air balloon.

When the burner heats up the air and fills it with air pockets, the balloon begins to rise. Because the heat of the flame continuously heats the air in the air bag, the volume and pressure of the air molecules in the air bag continue to increase, forcing the gas in the air bag to move towards the top of the air bag, thus generating buoyancy. In turn, when the flame is suppressed or the air cools, the gas in the air pocket cools down and decreases in volume, allowing the hot air balloon to descend.

Safety measures for hot air balloons.

Hot air balloons are a very safe means of aviation, but there are still some safety measures to be aware of when operating and flying. First of all, the quality and structure of the air bag and basket need to be ensured to ensure that it can withstand high temperatures and pressures. Secondly, the temperature and pressure of the gas inside the air bag need to be monitored at all times to avoid the danger of the hot air balloon rising or falling too fast.

In addition, in the event of bad weather in the weather forecast, it is necessary to interrupt the flight in time to ensure the safety of passengers. Finally, a qualified flight team and equipment are needed to ensure that the operation and maintenance of the hot air balloon are handled correctly.

Conclusion In general, as an ancient and fascinating aviation tool, the mechanism and working principle of hot air balloon have always attracted people's attention. From the manufacture of air bags to the heating of fuel, from lift control to safety measures, every aspect of a hot air balloon needs to be carefully designed and arranged to ensure that it is safe, practical and economical. With the development of aviation technology, the popularity of hot air balloons may not be as common as before, but as a tourist and entertainment tool, it still has a unique charm and value.

The principle of hot air balloon is the thermal expansion and contraction of air. The hot air balloon burner will burn the heated air from the port of the lower part of the airbag into the airbag, when the air is heated and expanded, it has a lower density with the outside cold air, and the specific gravity becomes lighter and rises upward, so that the balloon drags the gondola into the air together.

When the air expands when heated, the specific gravity becomes lighter. Because the mass of hot air per unit volume is smaller, hot air is lighter than cold air, and the hot air will rise above the cold air, making it lighter and generating buoyancy heat, which can make the balloon load lift into the air. After the hot air balloon lifts off, the combustion switch is used to adjust the ascent and descent altitudes.

When a hot air balloon is going to rise, it needs to constantly heat up the air.

When the hot air balloon is about to be lowered, you need to wait for the air to cool down. The only flying power of a hot air balloon is wind. For a hot air balloon flying around the world, it is necessary to choose a high-altitude air flow with the right speed and direction and move it accordingly in order to complete the flight efficiently.

The hot air balloon needs to use the wind direction of different altitude layers to control and adjust its forward direction, and its flight speed is the same as the wind speed, so the hot air balloon cannot actively change direction.

The hot air of the hot air balloon does not escape from the openings at the bottom of the airbag because the buoyancy causes it to rise. The balloon will continue to rise, with certain height restrictions, as the air eventually becomes so thin that the buoyancy is too weak to lift the balloon. Buoyancy is equal to the weight of the air expelled, so large airbags generally have a higher ascent height limit than small airbags.

The power of the hot air balloon is the burner, and its direction of movement must be to follow the wind. The wind direction is different at different heights, at different times, and at different locations, so if you want to adjust the direction, you need to find different wind layers.

The rise and fall of a hot air balloon is related to the air temperature inside the balloon, and when the air temperature inside the ball is high, the gravity of the balloon decreases, and when it is less than the buoyancy force, the balloon rises. The air temperature inside the sphere drops, and the buoyancy generated by the sphere is less than the weight and load of the sphere itself, and the balloon begins to fall.