https://www.janes.com/osint-insights/defence-news/defence/dsei-japan-2023-ihi-rolls-royce-progress-gcap-fighter-engine
2023年3月にIHIの方がJaneに
“We are now sending IHI engineers to Rolls-Royce and they are sending engineers
to us in Japan,” said Sato. “There are a lot of new technologies that need to be validated.
Another priority is the design of the engine to ensure it can be integrated into the new fighter aircraft.”

He said the two companies aim to develop an engine prototype by the late 2020s
to enable integration into the initial batches of GCAP fighters to be produced
from the mid-2030s. Initial tests of the engine will take place in the UK, he said.
と言っているのだから、いくら素人が間に合わないと言っても
GCAPのエンジンがXF9の派生型になるということはない
RRコンセプトのエンジンがGCAPには搭載される