Futuristic engine proves its mettle

Proponents of exotic aircraft engines called scramjets say the technology might eventually make it possible to reach any spot on Earth in a 2-hour flight (SN: 9/19/98, p. 182: http://sciencenews.org/sn_arc98/9_19_98/fob5.htm ). Yet, in more than 40 years of development, no scramjet-driven craft has ever made even a short hop under its own power.