The paper discusses the design and development of critical technologies for a "near-adiabatic" compound cycle turbofan engine (CCTE). The concept involves replacing the combustor of a conventional turbofan engine with a highly supercharged, high-speed, two-stroke, direct-injected diesel core. Primary emphasis was on reducing specific fuel consumption t o improve range x payload product. Critical diesel core technology areas addressed were: cylinder breathinglscavenging, fuel injection, combustion, materials and lubricants. Introduction thereby significantly reduce fuel consumption. For another perspective, a general comparison of "BSFC versus Shaft Horsepower" for the different engines is shown in Figure 3. A typical energy flow diagram for CCTE showing power splits between power producers and users, heat-recovery, and pressure losses for a typical cycle is shown in Figure 4. TYPICAL BRAKE SPECIFIC FUEL CONSUMPTION 200 [POUNOS ~UEL/HORSEPOWER-HOUR) t I \