1. Low BypassTurbofan/Ramjet Parallel Configuration (5)
2. At Mach 5 - 6.5, the thrust level is increased to make up for the increased aerodynamic drag as a consequence of an almost 90-deg flight turn.
3. Low BypassTurbofan/Ramjet Parallel Configuration @
4. Concepts 1-4 show approximately the same level of specific impulse in the turbo mode between Mach 0and approximately 3.5. The differences reflect the different nozzle pressure ratios. Concept 6 is inferior by approximately 20%. The low specific impulse of concept 6 in the transonic regime and between Mach 2.5 and 4 is caused by heavily overstoichiometric operation. In this case, overfueling was chosen to achieve a fairly compact engine despite the low air specific net thrust of this concept. Switchover to the ramjet mode occurs between Mach 3.5 and 4 except for concept 4. The intercooled turbofan/ramjet can be operated efficiently up to about Mach 4.5 in the turbo mode.