fats, yes it has talking about "thermostat controlled hydraulic cooler flaps".
G-2 had also manual system for that.
Can't recall any numbers of cooler flaps effect on climbing, but it was quite considerable.
Well, if their affect for speed was 50 km/h (= 31 mph ?), they effected greatly for climbing as well, tho.
When pilot dropped flaps down, also coolers back flaps were downed, I remember I've read something about flaps being somewhat poor on G-2, not sure.
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"Lentolaivue 21"
Flying for Bishops.