https://www.engadget.com/2008-06-24-darpas-vulcan-engine-combines-turbo-jet-with-scramjet-faces-wi.html
DARPA's Vulcan engine combines turbo jet with scramjet, faces will melt
Jun 24, 2008 - When you're building a jet that exponentially accelerates past Mach 6 -- as one does -- you need to come up with a way to get it off the ground. Scramjets, or...
vulcan engineturbo jet