Scramjets

Ordinarily a flame front in a continuous combustion situation cannot
travel upstream faster than speed of sound.  So in normal jet engine,
even if plane is flying supersonic, airflow in diffuser slows down to
subsonic where combustion takes place.

A scramjet would not require such a large diffuser and the slowing down
of internal airflow to subsonic.  How to keep it lit is one challenge-
there are others.

-- 
Don Stauffer in Minnesota
[EMAIL PROTECTED]
webpage- http://www.usfamily.net/web/stauffer