The X-34A is a NASA sponsored, unmanned disposable jet. Developed under the Hyper-X program, the craft cost $230,000,000. Its goal is to act as a prototype for the scramjet engine.
Dimensionally, the jet is quite small, only 12 feet in length. It is a black jet that looks more like a paper airplane than a real jet. While it does appear to have wings, the tail is more prominent. The top of the jet is quite flat which probably helps to generate lift.
The process is similar to how a missile works. The X-34A is dropped from a B-52B at about 40,000 feet. A Pegasus rocket booster carries it up to about 100,000 feet. Once the rocket booster's fuel has been fully expensed, it drops off, letting the actual jet fly by itself on its own power. The most interesting part of the jet is that the fuel it burns will only work at speeds over mach 5 and that during the entire self-sustained burn, it consumed only 2 pounds of fuel. It is right after the rocket falls off that the X-34A is flying at its highest speed. At the end of the flight, the X-34A will fall to the ocean.
The X-34A was flown the first time in 2001, but the rocket booster failed. However it failed due to the Pegasus rocket booster lost control during flight. NASA decided to try the flight again on March 27, 2004. To everyone's delight, the test flight went well, breaking the world speed record by flying at over mach 7 (about 2,382.03 m / s). NASA is planning on doing another flight sometime during 2004.