It has several tiers, each one containing different yantras (machines). The drawings show parts like cylinder, piston worm gear, and pumps which seem entirely modern (beyond 18th century).
From what is given in the following verses:
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Data / Information I : Ancient Aircraft Technology
According to the Dronaparva, part of the Mahabharata, and the Ramayana, one Vimana described was shaped like a sphere and borne along at great speed on a mighty wind generated by mercury.
Data / Information II : Indian Vimanas - Samarangana Sutradhara
In the dark firmament of devastation and uncertainty a silver lining was, however, seen in the efforts of King Bhoja in the 12th century, when he tried to compile the Sanskrit texts.
Data / Information III : Ancient Vimanas
The ‘Samaranga Sutradhara’ is one such text of 230 stanzas that gives you an elaborate description on the detailed technicalities of air travel.