WASHINGTON, April 23 (UPI) -- A U.S. military drone that hit 13,000 mph before crashing in the Pacific was damaged by the excessive heat of hypersonic flight, military officials say.
The tremendous heat generated as the Defense Advanced Research Projects Agency's Hypersonic Technology Vehicle 2 reached a speed of Mach 20 in its August 2011 test stripped the vehicle of its metal skin, DARPA officials said.