As an aside, Rolls Royce quickly realised the efficiency of high boost with low revs and second World War Merlin handling for long range cruise was throttle fully open but revs held down to 1700 with coarse prop via the speed governor.
I was unaware of the claimed second world war RR Merlin long range cruise policy. We certainly did not use those power settings when I flew Mustangs and Lincolns with RR engines in 1953
That policy might have reduced fuel consumption but was the cause of many engine failures at our squadron of RAAF Lincoln Mk 31 Long Nose equipped with RR Merlin 102 engines. We were a Maritime squadron.
To explain. The Pilots Notes for type recommended +6 boost and 2400 RPM for cruise. Mustangs and Lincolns.
Then an RAF exchange pilot arrived at the squadron in Townsville, Australia circa 1957. He had flown Shackletons in the RAF where low RPM and relatively high boost was engine handling policy. It might have worked on the Shack RR engines but was a disaster when used on the RR Merlins 102.
Following his advice on how to get better endurance for long range maritime operations at the low RPM /high boost combination, squadron crews were instructed to change from +6 /2400 RPM regime to +7 boost/ 1700 RPM. Fuel consumption improved markedly and everyone though we were on to a good thing. Except this writer Centaurus who was the squadron QFI.
The RAF chap out-ranked me as I was but a lowly Flying Officer and the RAF chap (a really pleasant well meaning bloke) had the ear of the CO. I felt more research was needed rather than word of mouth from someone who had vast maritime experience but on a different type of aircraft with a different RR design.
Within a few weeks we had the first engine failure on the RR Mk 102 followed by several more in the next few months. I suspected it was an engine handling problem as it seemed quite a coincidence the cluster of engine failures occurred at the new power settings introduced on the RR Merlin Mk 102's.
RAAF HQ started to ask questions and sent an engineering officer to investigate. He was a Flight Lieutenant and previously an NCO engine fitter on Lincolns at the squadron about five years earlier. By coincidence I had been an NCO pilot on Lincolns when he was there. A small world.
I was able to fill him in on the new policy of low RPM /high boost cruise introduced by the RAF former Shackleton pilot and upon which I had my reservations. However the HQ investigating officer was given short thrift by the squadron leader flight commander who was firmly of the belief that high boost and low RPM was the best engine handling technique for long range ops. If it was good for the Shackleton then it must be good for the Lincoln albeit slightly different engines. That was his theory, anyway.
The RAAF HQ investigating officer reported back to his Group Captain boss at HQ that in his opinion the engine failures were caused by poor engine handling. A rocket was sent to the squadron by HQ, directing the low RPM/high boost technique not to be used and to stick with the original power settings published in Pilots Notes Lincoln. The engines failures ceased and we went back to normal engine handling figures.