ISRO is August 2016 Successfully test launched supersonic combustion Ramjet (Scramjet) Engine. A ramjet is a form of air breathing jet engine that user the vehicle's forward motion to compress incomins air for combustion without a rotating compressor. A scramjet engine Is an improvement over the ramjet engine as it efficiently operates at hypersonic speeds and allow both subsonic and supersonic combustor modes. India is the fourth country to demonstrate the flight testing of Scramjet engine after the United Slates, Russia and European space Agency.