Hot air balloons-How do they work?

Even in this jet age where jet planes are common and aeronautics have taken the men to the moon we are still fascinated by hot air balloons which were the first type of light for men even before the Wright brothers flew the first aircraft.

Hot air balloons are the pioneers of men’s dream to fly and even to this date many of the people actually find them fascinating and that is why this brings up an interesting discussion as to how do hot air balloons work.

There are many people who like to fly but they do not want to go to any particular destination but just want to feel the thrill of flying to be above the ground at a greater height and for them hot air balloons are the perfect solution to experience the thrilling effect of flying.

If you have ever seen a hot air balloon in real life or in pictures you would realise that these are actually as compared to the weight which they carry and the secret to all of this lies in the way in which the hot air balloons actually work.

Theory behind the working of hot air balloons:

Have you ever wondered why does a boat float in water instead of sinking in water?

The hot air balloons work on the same principle only the medium which is water in the case of the boat is actually replaced by air in case of hot air balloons.

To answer our above question the reason the boat floats in water is because of the Newton’s third law of motion which states that to every action there is an equal and opposite reaction and therefore when the boat actually enters the water there is a force from the boat in the water and the water counterbalances it with the help of a proportional the pushing force due to which the boat does not sink in the water.

If you would realise the entire part of the boat does not flow on the water but rather there is always a small part of the boat which is inside the water.
why do boats floatThis is the part of the boat which is generating force on the water and the bigger the size of the boat the greater would be the part of the boat which is inside the water.

This is because if the boat is big then the counterbalancing force which is exerted by the water would also be big enough and this is only generated when a sufficient amount of the boat is actually submersed inside the water to generate this counterbalancing force which is pushing the rest of the boat upwards.

working principle

If you have not understood the above analogy then we would explain it in other terms. If you have noticed not all of the objects which we put into the water always float because some of the objects actually sink to the bottom where is some other float but what is the reason and what is the difference between the objects which are floating and the objects which are sinking.

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In more simple terms it can be explained as if you take a certain volume of water and if you take a certain same amount of volume for object and if the weight of the water is greater then the weight of the same volume of the object then the object would be actually floating on water whereas if the weight of the object is greater than the same amount of water volume -wise, then that particular object would not be able to float in water.

You can test both of these by taking a stone in one hand and taking the same volume of water in the other hand and you would feel the difference in the way it and then you can take some things are just plastic in one hand and take same volume of water and another hand and you will notice that the weight of same volume of plastic is actually much lesser than that of water and that is why plastic actually floats in water.

Analogy applied to hot air balloons:

hot air balloons

You might think that what these above analogies have to do with the working of hot air balloons but hot air balloons as we mentioned above work in the same way as a boat floating on water only the medium is changed to air instead of water.

If you have some knowledge about what air balloons then you would realise that the ear which is inside the balloon is actually heated which makes the air less dense and therefore this air is actually lighter than the more denser air which is surrounding it.

The most common example of this is the chimney which is spewing out smoke and other such cases.

The smoke which is coming out from such a chimney is heated in most of the cases due to the industrial processes and therefore this air and mixture of gases is less dense as compared to the air which is surrounding it and that is why if you have noticed that these gases do not come back down to the earth but rather travel upwards because they are less dense as compared to the air surrounding them.

If you are to catch this air in a polythene and close that polythene you would realise that the polythene actually travels upwards and starts flying. This is the basic concept of a hot air balloon.

You might think that when even a small amount of heated air is enough to make the polythene travel upwards why are the hot air balloons and the answer to that is that, depending on the weight of the you months which are travelling in basket which is attached to the hot air balloon, that he needs to be in a proper proportion to make that much amount of weight travel upwards.

The larger the volume of the hot air the more weight to the hot air balloon can carry and if you need the exact dimensions than four average adult person the size of the balloon which would be required would be 4 m in radius and the temperature of the year to which it should be heated to lift such a man would be 120°C and since most of the hot air balloons actually carry multiple adult men inside them it comes as no surprise that the size of the hot air balloons is so large.

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How does a hot air balloon work in real life?

There are normally three parts of a hot air balloon and the balloon itself is called as envelope which is the most important part of the hot air balloon then there is the burner and then the next and the third part of the hot air balloon is the basket in which the Lord or the people are carried. We would be discussing about each of these aspects of the hot air balloon below.

hot air balloons

Balloon(Envelope):
As we had mentioned about the balloon is also called as the envelope and it is usually made from a material such as nylon and the way in which this material or rather the balloon is sewn is breast itching vertical strips of nylon material known as gores.

These are stitched together very tightly to ensure that there is no leakage for the hot air from the balloon and it can handle the load of the hot air as well as the external atmosphere outside as well when it is in the air.

There are two vents in the balloon at the top and at the bottom of the balloon and at the top of the balloon the vent which is present is known as the ground and it can be opened with the help of a rope from the basket which is dangling below the balloon and this vent is open to let the hot air escape slowly from the balloon and this is used when you had to land the balloon.

The other vent which is present is just present about the burners to let the air in in sufficient quantity and it is generally made of materials which are fire resistance and which are not melted when they come in contact with fire and one such fireproof material is Nomex.

Burner:
As the name suggests this is the burner which is used to heat the air and it consist of propane cylinders which are used as the fuel for heating the air. The actual need for the heating mechanism is to just have a single cylinder which powers a single burner but to introduce some redundancy and to make the hot air balloon safer it is not pretty uncommon to use two or more cylinders powering two or more burners. When the duration of the right of the hot air balloon is more, you would find that extra cylinders are usually handled outside the basket so that they can be replaced when needed.

Basket:
You must have seen the wicker basket which is dangling just below the hot air balloon and this is where people are can’t go usually travels.

Needless to say in order to reduce the entire weight of the hot air balloon this is made from very light material so that it is able to easily fly with less amount of hot air and it is very durable as well and can handle weights up to a reasonable level.

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This basket is attached to the burners with the help of very strong ropes which can be eight or even more and in turn the burners are attached to the envelope which consist of hot air. This is the entire assembly of the hot air balloon.

Working of hot air balloons:

inside of a hot air balloonThe first trip of the hot air balloon start with opening up the balloon and laying it on the ground. You have to then tie the entire assembly that is you had to tie the envelope to the burners and you had to tie the burners to the basket to get the entire assembly ready. Then you have to use a fan to fill the envelope with cold air. After the balloon is filled with air then you start the burners to heat the air which is inside the envelope.

Depending on the weight which you want to carry you set a proper temperature for heating the air of to that temperature so that the entire hot air balloon is ready to fly. During this entire time the hot air balloon is tied to the anchors on the ground with the help of very strong ropes which hold them in place until you are ready to fly.

Once you are ready to fly you just take those ropes off from the anchors and the balloon takes off and controlling the multitude of the balloon is very easy because if you want the height of the balloon to increase then you had to keep on heating the air inside the balloon to a higher temperature whereas if you want to reduce the height at which the balloon is flying then you had to open the crown vent to let the hot air escape little by little and this would be replaced by the cold air and therefore the height of the balloon would reduce.

If you want to change the direction of the balloon then you are entirely dependent on the wind currents and therefore you had to study how to change the direction of the hot air balloon according to the wind currents and only once you are able to do that you would be in a proper position to control the hot air balloon entirely but even the professionals are reliant on the direction of the vent for changing the direction of the hot air balloons.

Inventors of the hot air balloon:
As we mentioned above even before the flight of the wright brothers the hot air balloon was invented by two French brothers by the names of Jacques-Étienne Montgolfier & Joseph-Michel Montgolfier and this was back in the 1740s and since propane powered cylinders were not available then they just use a simple heating mechanism which produced fire with the help of wood and straw. This was the start of the human flight much before it was given wings by Wright brothers.