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Failing the Mack 6 test, the USAF X-51A Waverider hypersonic jet is now lost over Pacific. Air Force spokes man said that a faulty fin control prevented it from starting the scramjet engine.

The wingless 8-meter prototype was dropped from a 50-meter wing of a subsonic B-52 bomber after it ascended to a height of 15,000 meters (50,000 feet) from the U.S. Edwards Air Force Base, in California.

The X-51A is critical for US missile development as the high velocity makes detection difficult.

There were similar programs in Soviet Russia where Raduga and NPO Mashinostroyeniye had researched hypersonics but did not produce a missile after Soviet Union collapsed.

Australia's Queensland Univ has a HyShot and Hycause research program.

In India, Brahmos, which currently produces supersonic cruise missiles, has announced a hypersonic Mach 7 version of the missile. Its a JV with Indian DRDO and Russia's NPO Mashinostroyeniye.