Boost (Hurricane 1 and Merlin II/III)
I've been wading through some old manuals as part of a private project looking at the Hurricane 1.
I understand MAP and CS props well enough on modern aeroplanes, but I'm struggling with how this maps to "Boost" as used on the Merlin engine. Can anybody explain what Boost actually is and is controlled - is it just an alternative term for MAP, or as I suspect something defined a bit differently?
At the same time, references to the early CS props on the Hurricane 1 / Merlin II combination refer to a "2 speed" prop, which suggests a CS prop with only two RPM settings - as opposed to the infinitely variable lever I'd see on a modern aeroplane. Is that correct, or is it more modern than I think, or even is it a 2-pitch (fine and coarse) prop such as is fitted on one or two modern motorgliders?
And if anybody knows the answers to those, I'm guessing that they might know the answer to my third question. At what point was the 2 blade fixed pitch prop finally withdrawn from the Hurricane fleet?
Cheers chaps.
G