<span style="color: #222222;">Prime Minister Narendra Modi has congratulated DRDO for successful flight of the Hypersonic Test Demonstration Vehicle today.</span><br />'' <br />'' <span style="color: #222222;">In a tweet, Mr Modi said, the scramjet engine developed by DRDO scientists helped the flight achieve a speed 6 times the speed of sound.</span><br />'' <br />'' <span style="color: #222222;">He said, very few countries have such capability today.</span><br />''