From: KurzweilAI.net

Falcon Hypersonic Technology Vehicle 2

In its second flight test, the Defense Advanced Research Projects Agency’s (DARPA) fastest (13,000 mph) aircraft ever built, the Falcon Hypersonic Technology Vehicle 2 (HTV-2), was successfully inserted into the desired trajectory at near-orbital speed, but the flight  ended in loss of signal (and control) when the aircraft transitioned to Mach 20 (about 13,000 mph) aerodynamic flight around nine minutes into the flight, DARPA announced Thursday.