Supercharging & stuff - losses, improvements, good vs. bad. vs. excellent etc

In order not to clog another thread.

Shortround6 said:

Look at the Merlin VIII engine or Merlin X engine in low gear to see the effect. Same supercharger turning slower is allowed to use higher boost and/or heats the intake air less.

Some people just lumped everything going on at low altitude into 'throttle loss' rather than go through a long explanation.

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The decease of power due to the 'throttle losses' ought to be smaller for the engines with the low-speed gear (MS in British speke) than on the engines that are without that gear. It was not just what the 1-speed FS Merlins (like the Mk. II, III, 45, 47 or 50) experienced, but also the V-1710s.
One of the appeals of the swirl throttle was that it was supposed to cool the air a little bit, that helped with the power generated.
link
End result on the AM-35A engine (that was with power comparable to the Merlin 45/50 on +9 psi) was the gain of 100-150 HP at S/L.

Similar was the thing with the HS-12Y-45 vs. the -31 - the controllable vanes before the impeller allowed for the much lower loss of the power under the FTH, despite the -45 having a much more capable supercharger.

American test
Graph, comparing the boost (full lines) and power (dashed lines) of the run-on-he mill HS 12Y engine and the -45:

tomo pauk said:

In order not to clog another thread.

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It's a pity that my two efforts in that other thread (If German have access to high ocatane fuel, how does that impact the performance of their fighters? and If German have access to high ocatane fuel, how does that impact the performance of their fighters?) to explain why the difference in Merlin BHP between sea level and FTH has nothing to do with some mysterious "throttle loss" but are only the result of change in ambient air temperature between sea level and FTH, seem to have been a waste of my time.

Daggerr said:

It's a pity that my two efforts in that other thread (If German have access to high ocatane fuel, how does that impact the performance of their fighters? and If German have access to high ocatane fuel, how does that impact the performance of their fighters?) to explain why the difference in Merlin BHP between sea level and FTH has nothing to do with some mysterious "throttle loss" but are only the result of change in ambient air temperature between sea level and FTH, seem to have been a waste of my time.

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2-3 comments are warranted:
I value you input. On a public forum, people often disagree, however.
Term of the 'throttle losses' is not my invention.
Better/more efficient/less 'harmful' ways of throttling (that can be called by other names,) were invented and put into use back in ww2, with the net effect of allowing for the better power under the FTH than it will be otherwise the case.

Something was going on. And it was more than the difference in ambient temperature.