It hurtled alone at 5 times the speed of sound for 3 and a half minutes. It covered 213 nautical miles in just over 6 minutes across the skies of California. The US Air Force says the craft was intended to demonstrate the new technology, not as a prototype for new weapons. It was the last 4 X51A craft built by Boeing. The end of the dramatic journey was a little less than glorious. It was crashed into the Pacific ocean in a controlled dive.