The U.S. Air Force has failed in its attempt to fly its hypersonic jet Waverider at Mach 6 (5795km/h).
The unmanned X-51A WaveRider was launched over the Pacific on 14 August from above the Point Mugu Naval Air Test Range in a key test to fine-tune its hypersonic scramjet engine.
After the launch and about 15 second into the flight, a fault was identified in one of the aircraft's control fins, and it was not able to maintain control and was lost.
"It is unfortunate that a problem with this subsystem caused a termination before we could light the scramjet engine," Charlie Brink, of the Air Force Research Laboratory at the Wright-Patterson Air Force Base in Ohio, said.
"All our data showed we had created the right conditions for engine ignition and we were very hopeful to meet our test objectives."
This is the third time that the U.S. is unable to use the technology as planned. In its latest attempt, it flew at its maximum speed for five minutes.
The Pentagon, which helped fund the project, has been testing hypersonic technologies in an effort to develop faster missiles.
Besides, the research can be also used to build a commercial plane with the promise of London-New York trips taking as little as an hour, or even Tokyo-Paris in two hours.