Here's a refutation of the Vaimanika arguments, by a group of Indian scholars at the Indian Institute of Technology at Bangalore, from 1974.  PDF attached to this email.

H. S. Mukunda, S. M. Deshpande, H. R. Nagendra, A. Prabhu, S. P. Govindaraju, "A Critical Sudy of the Work Vymanika Shastra" in Scientific Opinion, 1974:5-12.

Dominik Wujastyk