AZHRAE Rocket
The Advanced Zero speed to Hypersonic Regime Airbreathing Engines or AZHRAE inlude a wide variety of exotic engine types designed, unlike turbine engines and ramjets, to function at low (takeoff and landing) speeds, where they function as turbojets, hy hypersonic speeds for high-altitude operations, where they function as ramjets, and in suborbital or orbital insertion profiles, where they close off their intakes and function as rockets, As a group these are refered to as "ducted rockets," and are the preferred engines for trans-atmospheric craft.
While operating in turbojet or ramjet mode, the engine uses jet engine fuel, usually a hydrocarbon distillates. While operating in rocket mode it requires a liquid hydrogen/oxygen rocket fuel mixture. This requires a dual fuel system for mounting these engines.
AZHRAE engines are developed as a late TL-8 technology as a competetor to contragrav lift systems.