Say the words "coal-powered engine," and images of men shoveling black rock into the fiery
belly of a steam engine come to mind. However, liquid fuel made from coal instead of oil may
shoot the next generation of supersonic jets across the sky.
If flight speeds are to increase, jets will require new fuels that don't fall apart chemically in
engines that become extremely hot, says fuel chemist John M. Andrésen of the Energy Institute
at Pennsylvania State University in State College.
Currently, the F-15 Eagle jet fighter can reach speeds two and a half times the speed of
sound. The U.S. Air Force is working to build a jet that will fly at eight to nine times the speed
of sound, Andrésen said last week at the American Chemical Society's spring national meeting
in San Francisco. The engines in such future supersonic jets could get hotter than 450C.