How does one design a propulsion system that combines a full-scale turbine engine and a Constant Volume Combustion (CVC) engine that is capable of delivering 12,000 pounds of payload up to 9,000 nautical miles from the continental United States in less than two hours? DARPA has released new details on how they plan on tackling this issue with their Vulcan engine—a ramjet / scramjet hybrid that will take an aircraft like the Falcon HTV-3X from 0 to Mach 4 with a traditional turbine engine, then kick in the CVC to push it to Mach 6 and beyond.
Obviously, that would streamline a process that currently requires a second aircraft to take the plane up to the supersonic speeds necessary to engage a CVC "scramjet" engine. Like all of DARPAs projects, the Vulcan engine is definitely an ambitious undertaking—and the 2012 date they set to have a working prototype doesn't help matters. Check out Aviation Week for more technical details on Vulcan. [Aviationweek via Crave via DVICE]