NASA study for a next-generation supersonic passenger jet that would fly 300 passengers at more than twice the speed of sound.  Technology to make this possible is being developed as part of NASA's High-Speed Research program, supported by a team of major U.S. aerospace companies in a multi-year research program begun in 1990.
<a href="//commons.wikimedia.org/wiki/NASA" title="NASA">NASA</a>
<a rel="nofollow" class="external free" href="http://lisar.larc.nasa.gov/UTILS/info.cgi?id=EL-1998-00001">http://lisar.larc.nasa.gov/UTILS/info.cgi?id=EL-1998-00001</a>