The X-51A WaveRider unmanned experimental scramjet was on its way Tuesday morning from Edwards Air Force Base, 114 miles north of Los Angeles, to Point Mugu Military Base, 52 miles east of Los Angeles, for a historic test flight. The jet will attempt to maintain sustained hypersonic flight for longer and faster than it did in its first self-powered test flight on May 26, 2010.

If successful, Tuesday's test flight over the Pacific Ocean near the base will mark the first time a so-called scramjet has held a velocity of over five times the speed of sound for at least 300 seconds.

"Attaining sustained hypersonic flight is like going from propeller-driven aircraft to jet aircraft," Robert A. Mercier, deputy for technology in the high speed systems division at the Air Force Research Laboratory in Ohio, told the Los Angeles Times. "Since the Wright brothers, we have examined how to make aircraft better and faster. Hypersonic flight is one of those areas that is a potential frontier for aeronautics. I believe we're standing in the door waiting to go into that arena."

What the X-51A will not do, however, is break any unmanned aircraft speed records -- that's a record held by an earlier scramjet, the X-43A, which on Nov. 16, 2004, travelled for 10 seconds at almost 10 times the speed of sound, or more than twice the speed of the fastest conventional bullet.