is the 'ancient Indian aircraft manual', the Vaimanika Shastra, actually ancient? checked it and oof

People keep dropping the Vimana / flying-machine thing like it's case closed: 'ancient India had detailed AIRCRAFT MANUALS, the Vaimanika Shastra, with mercury engines and fighter planes, suppressed knowledge!' I wanted it to be cool so I dug. It is not what the meme says. The ancient epics (Ramaya……