Russia and China have recently touted their progress in developing hypersonic vehicles, which fly much faster than the speed of sound, which is 767 mph. Hypersonic missiles are rocket-boosted to high altitude and may be launched from land, sea or air. They fly far faster than any other weapons – more than 3,000 mph and potentially up to 10,000 mph – which makes them difficult to identify, avoid or shoot down. After leading the development of this technology area for decades, the U.S. finds itself behind and investing heavily in the technology to try to keep up.
I am a professor of aerospace engineering at the University of Michigan, and one of my primary research areas is in the development of computational models to help design hypersonic vehicles. The research is funded by the government and private industry. I have led studies on hypersonics for the government.
Over the past 60 years, U.S. interest in hypersonic vehicles has waxed and waned. An early success was the X-15, a hypersonic test aircraft with a maximum speed of 4,500 mph that was flown from 1959 to 1968. The X-15 flew 199 times and only experienced two failures, of which one resulted in the death of the pilot. It set the stage for the development of the space shuttle, which flew from 1981 to 2011. The next ramp-up in hypersonic activity was the National Aero-Space Plane Program, from 1986 to 1993, which never built a prototype.
A recent success was the X-51A, from 2005 to 2013, which set a world endurance record for sustained flight of a hypersonic vehicle powered by a high-speed propulsion engine called a scramjet. However, there were only four flights, of which flights two and three were not fully successful. In addition, there were no plans in place for any follow-on at the end of the X-51A program.
Now it seems the U.S. is back in the hypersonic effort in a serious way. The Pentagon has declared hypersonics to be its number one research and development technical priority. The president’s recent budget request proposes allocating almost $3 billion to develop hypersonic weapons and defense systems against potential adversaries’ hypersonic weapons.