This post looks at the mythology of Kubera’s Pushpaka Vimaana (the aerial chariot), that was snatched away by Raavana after he defeated Kubera in battle. This Vimaana was used by Raavana to abduct and carry Siita away to Lanka. This has been described in the great epic Ramaayana, written by Vaalmiiki.
What is the truth behind the legend of the Vimaana? Was the Vimaana just a part of the fertile imagination of the poet (Vaalmiiki)? It is only natural for people to dream of flying in the air like the birds. Our epics and puraanas are full of stories of people appearing and disappearing at will, travelling in the air, having birds as vehicles etc.
In early imagination, flying machines would be built like a bird and would flap a pair of wings to achieve flight. There are also flying machines that just floated in the air (though heavier than air!) through magical powers. The magic carpet of early imagination was one such. After many failed attempts at creating a flying machine with flapping wings, people realised that such a machine was impossible due to structural and other issues. And thus they came to the conclusion that it would be impossible to get anything heavier than air to fly.
Then, what is the Vimaana? Was there a flying vehicle that Raavana used? If there was a flying vehicle what was it likely to have been?
It is very likely that the Vimaana was the result of the poet’s brain working overtime. However, if it was not, and the Vimaana was a real flying machine, what would it likely have been? This post tries to analyse this and look at one possible option for what the flying machine could have been.
What was the flying machine?
We argue that the Pushpaka Vimaana could have been a hot air balloon with a passenger basket attached at the bottom. This balloon was maintained at a very low height and pulled by horses or men using a long tether rope.
We are clear that the Vimaana was not something that was heavier than air. It would have been structurally impossible to build one and there are no indications that there was knowledge of the workings of aerofoil shapes and surfaces.
In the following we first look at references to the machine (called a chariot) in the Raamayana. We find that the references can indicate a hot air balloon with a basket. We then look at the technical aspects of making such a balloon and find that it is not impossible for the engineers of that period to build such a machine.
Can the Ramayana references mean a hot air balloon and basket?
When Raavana was ready to carry Siita away, he summoned that his chariot be brought to him.
Raamaayana 3.47.18 says
sa ca māyāmayo divyaḥ kharayuktaḥ kharasvanaḥ
pratyadr̥śyata hemāṅgo rāvaṇasya mahārathaḥ
“Then the magical, celestial, great chariot of Raavana appeared with a harsh sound, golden-bodied and yoked to mules [horses]. ”
[Then (saḥ ca) the magical (māyāmayaḥ), celestial (divyaḥ), great chariot (mahārathaḥ) of Raavana (rāvaṇasya) appeared (pratyadr̥śyata) with a harsh sound (kharasvanaḥ), golden-bodied (hemāṅgaḥ) and yoked to mules [horses] (kharayuktaḥ).]
The verse above says that the chariot appeared (was suddenly seen). The best possible scenario to justify this description can only be that it was pulled down from above. The verse says that it was celestial. The verse also says that the chariot was golden-bodied. This could mean that there was a yellow glow in the chariot which points to a fire burning in it. The other point is that there was a harsh sound. Could this not be that of fans (bellows?) keeping the fire going?
One possible conclusion we can draw from this description is that the chariot mentioned in verse 3.47.18 is the basket of a hot air balloon.
[Note that the word “khara” can also be an adjective meaning (among others) “dense” as applied to clouds. If this thinking can be extended further, it can mean dense as applied to dust. In Sanskrit as in other languages, an adjective can stand for the noun it describes. For example “krūraḥ” can stand for “krūraḥ manuṣyaḥ.” In Sanskrit the distinction between nouns and adjectives is quite wavering. Even in English, this is common. For example, we use the adjective blue to mean sky. [In the wide blue]. Using this logic, “khara” can mean dust. Then the word “kharayuktaḥ” could mean “accompanied by dust.” This would further buttress the theory that the chariot “appearing magically” was it being pulled down, raising a lot of dust. Of course, this is rather laboured logic, but pointing to a possibility, nonetheless!]
The second important piece of information comes from the following verse: 3.49.14. This is one of the verses that describe the fight between Raavana and Jataayu.
varaṃ triveṇusaṃpannaṃ kāmagaṃ pāvakārciṣam
maṇihemavicitrāṅgaṃ babhañja ca mahāratham
pūrṇacandrapratīkāśam chatram ca vyajanaiḥ saha
“[Jataayu] broke the mighty chariot whose sides were made with three bamboos, whose body was brilliantly studded with gold and pearls, which could travel at will and which was a flash of fire. [Jataayu also broke] the umbrella [or mushroom] resembling the full moon along with the fans.”
[[Jataayu] broke (babhañja) the mighty chariot (mahāratham) whose sides (varaṃ) were made with three bamboos (triveṇusaṃpannaṃ), whose body was brilliantly studded with gold and pearls (maṇihemavicitrāṅgam), which could travel at will (kāmagam) and which was a flash of fire (pāvakārciṣam). [Jataayu also broke] the umbrella [or mushroom] (chatram) resembling the full moon (pūrṇacandrapratīkāśam) along with the fans (vyajanaiḥ saha).]
The chariot of Raavana is made with bamboo (on all sides). This clearly indicates a basket that would be used under a hot air balloon. The chariot is also called a “flash of fire”. This removes all doubt that there was fire being used in the basket.
The verse talks of Jataayu breaking (collapsing) the umbrella (or mushroom) resembling the full moon. This sounds like the description of a balloon. Jataayu also broke the fans (bellows?). This also makes it clear that there were a couple of servants in the chariot who were fanning the flames to keep the air in the hot air balloon hot.
Let us look at another verse 3.49.13
kāñcanoraśchadān divyān piśācavadanān kharān
tāṃś cāsya javasaṃpannāñ jaghāna samare balī
“The mighty [Jataayu] killed in battle his [Raavana’s] swift and divine mules [horses], those who were golden-armoured and demon-faced”
[The mighty (balī) [Jataayu] killed (jaghāna) in battle (samare) his (asya) [Raavana’s] swift ( javasaṃpannān) and divine (divyān) mules [horses] (kharān), those (tān) who were golden-armoured (kāñcanoraśchadān) and demon-faced (piśācavadanān)]
This indicates that the basket was yoked to horses. This shows that the basket was kept in the air by the hot air balloon and was tethered to and pulled by horses on the ground. This would ensure that the passengers in the basket would be able to travel without too much bounce due to the uneven ground. The movement of the chariot and the basket must have been quite slow. This is why Jataayu could catch up with the chariot and fight with Raavana.
There are also many other verses where Siita is said to shine like flashes of lightning and Raavana is said to shine like a mountain set ablaze. All these again pointing to some sort of fire in the basket
Another verse, this time from the Yuddha Kaanda (6.47.7) removes all doubt. This verse clearly talks of the chariot shining due to a flame
sa evam uktvā jvalanaprakāśaṃ; rathaṃ turaṃgottamarājiyuktam
prakāśamānaṃ vapuṣā jvalantaṃ; samārurohāmararājaśatruḥ
“Having spoken thus, he [Raavana], the enemy of Indra ascended [his] chariot that was shining due to the fire in it and blazing [due to the fire] and that was yoked to a row of the best horses and that was shining due to its beautiful form.”
[Having spoken (uktvā) thus (evam), he (saḥ) [Raavana], the enemy of Indra (amararājaśatruḥ) ascended (samāruroha) [his] chariot (ratham) that was shining due to the fire in it (jvalanaprakāśam) and blazing (jvalantam) [due to the fire] and that was yoked to a row of the best horses (turaṃgottamarājiyuktam) and that was shining (prakāśamānam) due to its beautiful form (vapuṣā).]
This verse is very clear. It says that the chariot was shining because of fire in it [jvalanasya prakāśaḥ yasmin saḥ jvalanaprakāśaḥ]. Or it might be that the chariot is visible (prakāśaḥ) due to the fire [jvalanena prakāśaḥ jvalanaprakāśaḥ]. This strongly points to a fire to keep the air in the balloon hot.
From the verses above, we get a picture of a chariot made with three bamboos as the mainstay. It was celestial. It was yoked to horses. It had a fire burning in it. There were fans (bellows) fanning the fire making a harsh sound. There was an umbrella like thing on top. The chariot could appear and disappear when needed (can be pulled down or left to go up). What else but a hot air balloon can fit this description?
Technical aspects of the balloon
The fact that hot air is lighter than cold air and therefore would rise up was known to the people of that period. Indeed, they would have observed this on a daily basis, when they saw the smoke from their sacrifices going up. It would therefore not be too much to believe that the people of that period realised that a balloon like thing filled with hot air would rise.
The hot air balloon would have been made of leather – leather that is about a tenth of a couple of millimetres thick would be enough. Leather is comparatively light and is very fire resistant [so burning a fire in the basket would not be a fire hazard]. Technology of that period was quite adept at handling leather. Large sheets of lather of the required thickness would be stitched together in the shape of a balloon with an opening at the bottom. The balloon leather would be strengthened with wooden struts. There would be also be special struts attached to the balloon to carry the basket.
What would be the required size of the balloon? To figure this out we would need to know the weight it has to carry.
Let us assume that the basket is designed to carry four people [Raavana, a guest (like Siita) and two servants for handling the fire and the fans or bellows. Leather itself is not very heavy. If we consider a .2 mm thickness of the balloon, one that encloses a space of 2500 cubic metre would weigh approximately 160 kgs. If we add the stitches, struts etc. and the basket (which I assume would be very small) we can look at a maximum weight of around 200 kgs for the balloon and basket. The fuel (wood and oil) for burning would be another 50 kgs. [My thinking is that Raavana would use the balloon only to show off his prowess. It would not be practical to use it for long distance travel. So this amount of fuel carried would be enough].
We can thus look at a total weight of the hot air balloon (including people and the basket) as approximately 500 kgs.
What size of balloon would be needed to lift this 500 kgs? The density of air at standard temperature and pressure (20 degree Celsius and 1013.25 hPa) is around 1.2 kgs per cubic metre. Air heated to around 100 degrees Celsius would have a density of around 0.95 kgs per cubic metre. So to generate a lift of 500 kg-force would require a balloon volume of around 2000 cubic metre (500 divided by 1.2 minus 0.95). . Even if the external temperature is around 30 degrees (at air density of 1.16 kgs per cubic metre) the balloon volume needed would be (500 divided by 1.16 minus 0.95) around 2400 cubic metres
So a leather balloon enclosing around 2500 cubic metres would be sufficient to hold the basket (chariot) off the ground.
It is rather large, but not technically out of reach for the engineers of that period. Engineers, artisans and leather workers routinely built leather armour during that period. It was also clear that they built wood and leather bridges. They were also adept at building large chariots that would be used in battle and for transportation. They were also good metal workers. These skills and technologies have been attested to even in the Vedas.
So building a hot air balloon and outfitting the basket would not be a challenge for the engineers of that period. Can the air in the balloon be heated to the required temperature (100 to 120 degree Celsius)? Heating the air initially and getting it to balloon up and into the air would certainly be a challenge. I estimate the weight of the balloon itself (not counting the basket) to be about 150 kgs. To lift this (just the balloon) off the ground would require around 600 cubic metre of air to be heated to around 100 degrees (or more air to a lesser temperature. Once the balloon lifts off the ground, it would not be difficult to heat up the air inside. Once it gets into the air, my assumption is that it would be permanently kept hot with servants burning fuel all the time. Bellows (fan) made of leather would have been used to fan the flames and to direct the hot air into the balloon.
Based on the above we can conclude that there is a good possibility of the Pushpaka Vimana and other aerial chariots mentioned in our epics and other ancient literature could be hot air balloons. It would have been impossible for them to be a heavier-than-air machines. The references in the Ramaayana to the fire in the basket, to the umbrella / mushroom above, to the sound of the bellows: all these point to a balloon. We also find that it was not impossible for the engineers of that period to have built such a machine.
Thanks to my friends VK Kumar and Sivaguru for reviewing this and suggesting improvements.
Some useful links
There are a lot of articles and posts in the internet about the Vimaana. Many people have dismissed the Vimaana outright as just a myth. Some have gone in the other direction and have tried to show that the Vimaana could have been even a rocket! I am not taking any sides in this argument. My attempt was to explain what the Vimaana could possibly have been, based on the science and technology available then, if the Vimaana had indeed existed.