FP:
The Merlin had been running for some years before Hooker arrived at R-R in Derby, so the initial impeller design was not his. What he did was initially to improve the airflow through it, as in the Merlin XX and 45, then later introduced the 2-stage supercharger that raised engine power further. There's no need to take umbrage - but I do think it's worth being accurate. It's all in his book, in front of me now.
Regards,
KP
Last edited by kenparry; 19th Jul 2021 at 14:01.
Reason: typo