Supersonic is fast enough for some people; hypersonic is what the military is after.

The Pentagon has released the results of it's first test of a hypersonic aircraft that took place last August.  The DARPA project-Defense Advanced Research Projects Agency-developed the aircraft with the idea of traveling at Mach 20, or twenty times the speed of sound.   Hypersonic refers to craft who travel at least five times the speed of sound.  While spaceships travel at tremendous speeds,  hypersonic aircraft dont completely leave the earth's atmosphere. 

 The DARPA test involved an arrow shaped unmanned vehicle called Falcon 2, that was carried aloft by a rocket from Vandenburg Air Force base.  At an unnamed altitude, the craft separated and returned to the lower atmosphere where it glided at 20 times the speed of sound.  The craft successfully flew for at least three stable minutes before heat panels peeled off, causing the craft to flutter and crash.    The purpose of the DARPA project is to eventually build a military aircraft that could be anywhere in the world in less than an hour.  

    How fast is it?   Imagine New York to Los Angeles---in 12 minutes!  This was the second flight of the Hypersonic Plane, but no further test flights are planned, at least not for now.