I have had a lot of people coming up with interesting comments on the Vimana. Here are a few view points! These are not discoveries made by these individuals, but ideas that have quite taken their fascination.
Mr. Joshi, a retired civil engineer doing his own research, a very interesting personality with unique ideas and experiences to narrate, is of the opinion that the pyramidal structure had a very close relation to the pyramids in egypt as well as those in Gautamala peninsula of the Mayas, conceptually, as its believed that there is a point in the center of the pyramid that holds mysteries of keeping anything lasting longer within its interiors.
Taking his view further, its indeed true that in the large pramid at giza, the kings chamber is exactly one third the distance from the bottom. This spot offers exceptional energies that increase the immortality curve for anything thats is perishable within its space(a mummy probably in this case as the egyptians are known to enbalm their dead). How does this apply to a vimana (dravida style down south in india, nagara style in north india or angkhor wat in cambodia) is anyones guess.
Srinivasan, a cartoonist, a coleague and a good friend of mine is of the opinion that vimanas are mainly vehicles or 'viman', which suits the temples as most of them were "chariots of the Gods". The pushpaka vimana(ravana abducted sita using this vehicle) has quite intrigued him, as a machine that has been described to be used to fly across the sky to transport devas and other divinities, and strictly has a charioteer. The science of this is of course lost maybe, but it does throw a lot of light on the Rathas as a vehicle. At ellora of course, there is a depiction of a chariot with sita while ravana fights jatayu.
The third opinion on the vimana is that it is a part of a larger structure that represents the human body, starting from the stupi (head) , the gala (neck) the vimana (body) ending in the kapota(roof) , the bhiti (walls) housing the garbha griha(womb house), the mandapas (legs), and finally the gajastambha as the feet. It depicts the human body seated with legs outstretched.
What ever the vimana ultimately meant, it reached the pinnacle of expression in the temple of tanjore and gangaikondacholapuram in the south and that of khandriya mahadeva in the north, at khajuraho. Its depiction raises serious question on what a vimana was viewed to be. Was it a pyramidal structure that defined the path to heaven for the human soul to rise, was it a pyramidal structure that preserved perishable material for longer within its walls or was it a Chariot that flew across the sky transporting celestial beings.Was it a representation of mount kailasa with all its minor vimanas tapering towards the highest pinnacle or was it a representation of the human body being the personification of the atman within?
Honestly, i wouldnt know! Please let me know what you think!