109 prop pitch (rpm) and the supercharger

[Robo.]

Originally Posted by camber

Crumpp as others have stated, Steinhilper is clearly not complaining that rookies fell behind because of their inability to manually duplicate a CSP (i.e. continuously changing their variable prop pitch for a constant optimal rpm).

Yes but mind you this only applies at very high altitudes. Fiddling with the rpm, as he describes it, was because of the supercharger design and function, not because of trying to mimic the CSP. Apparently this practice made a difference in average speed up there.

The chap falling behind on the other hand, that was while they were climbing below fth. He was simple a rookie pilot fresh from the training and due to the lack of experience he could not use the manual rpm lever at all and was struggling to keep up. After he got an order to turn back to France he got the navigation wrong, too, and was heading straight to the UK. At this point Steinhilper left the formation and herded him back to the correct heading.

The two 'rpm quotes' are totally unrelated.

Originally Posted by camber

From his account he believed that he could only get optimal performance from pulsing the rpm, i.e duplicating a CSP with the rpm control being moved back and forth. This seems a little odd, and we must consider that it wasn't actually true. Perhaps if the rookie pilot managed to manually control his rpm at an optimum value like a CSP, he could have overtaken Steinhilper busily pulsing his rpms back and forth.

See explanation above - pulsating the rpm is only applicable at high altitudes way above the FTH.

He got shot at and baled out because he was using his older 109 that was not in use for a while, there was some condensed water in the propellel hub and that water froze up in the altitude so he could not change the prop pitch and overreved his engine quite badly.

Originally Posted by camber

It is hard to state a good technical reason why the pulsing would have helped. Steinhilper believed that the thrust from the rpm boost could only occur if rpm was dropped again, implying that the extra rpm was high enough to not increase thrust.

Good technical reason was the supercharger function at that alt and rpm, just as you said below.

Originally Posted by camber

Perhaps 109 pilots decided it was OK to exceed rpm limits if they only did pulses above the limit, they achieved some extra thrust and speed this way but mistook the reason. Or perhaps a quirk of 109 engine/supercharger/prop design did allow a small performance increment doing this over maintaining rpm at a constant optimal value.

Yes they decided so, because it obviously worked, they knew why it was working that way, even Steinhilper explains that in the book. Overreving the engine at altitudes above FTH was actually approved and recommended by LW authorities shortly after the BoB. There is no doubt the pilots knew what they were doing, at least in my opinion... Again this does not apply for flying below the FTH.