Vaimanika Shastra means the science of aeronautics. To understand aeronautics, we need to understand aerodynamics, propulsion devices, materials, and metallurgy. In Vaimanika Shastra, there is much about propulsion devices and aerodynamics. The focus of the book is on the vimanas mentioned in many ancient epics, such as Rigveda, Mahabharata, Ramayana, and others. According to Vaimanika Shastra, these vimanas were not sophisticated flights from previous authors, but real and aerodynamically viable flying machines. The ancient Indians not only knew how to fly but also flew in highly sophisticated machines with many capacities. Using mercury vortex motors, these vimanas can remain motionless in the air and become invisible. When used in war, they can leave enemy forces unconscious and spy on enemy ships.