Aviation Week did a piece on the planned GCAP engine demonstrator:
https://aviationweek.com/defense/ai...-engine-focuses-thermal-electrical-management
https://aviationweek.com/defense/ai...-engine-focuses-thermal-electrical-management
Following the unveiling in 2018 of proposals for what was then the UK-only Future Combat Air System, Rolls had indicated it could adopt a three-stream adaptive- or variable-cycle architecture. Early graphics suggested the engine could employ a controllable third-stream bleed system. However, further analysis of adaptive architectures appears to have prompted a reassessment, particularly now that engine development work has widened to three countries.
“We understand the adaptive engine, and we have looked at that technology for the mission set this aircraft will face, and we do not believe it earns its way onto the aircraft,” Tivey explains. “You will get benefits from such an engine—an economy mode and a warfighting mode—but the trade-off between the cost and the capability is a pretty fine one, and we do not think it is justified in the mission set for GCAP.”
Today, the primary building blocks for the future engine have prioritized thermal signature management and electrical output. The result will be a power and propulsion system that Rolls considers more integrated into the aircraft platform than any engine before it.
Tivey describes the engine as “fundamental” to the integrated systems onboard the aircraft, rather than simply a separate subsystem that has been bolted on. Rolls engineers have been part of the GCAP and UK Future Combat Air System Technology Initiative (FCAS TI) development efforts from Day 1, he says, noting that the propulsion and power system directly influences the fighter’s design.