The web comparison as well as the in-game (hangar) climb charts show distinct different rates of climb for the B-17 and the B-24 up to about 25K
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However, when testing them in every possible configuration, the rates of climb of both bombers have been almost identical, when by looking at the HTC charts one would expect ~25% faster climb to altitude for the B-17.
These are times to climb with MA fuel burn settings (2.0), rounded to the nearest full minute:
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So I went on to do another test, this time measuring the ROC @5k (autoclimb), this time with a fuel burn of 0:
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So... is there either a bug in the generated charts, or the autoclimb in game does mess up the climb of at least one of the bombers... or are the climb charts are generated with very different configurations for both planes?