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Dave:
The material on the 220s failures doesn't clarify whether the problems could be attributed to cold oil at start-up or high altitude operation at cold temperature. The problem was quite apparent there in the Summer and Fall of 1918 when Hartney "damned" the XIIIs so it was quite possibly a problem not of seasonal cold weather but of the nature of cold oil viscosity at start-up. The problem evidently existed only in the 220 (geared version) of the Hisso so apparently it was not related to the same problem facing whoever modified the MB: ie he had a concern with bottom end overpressurization whereas the Hisso only lost the lube to the gear reduction housing and no mention has been made- to my knowledge- of bottom end problems with the H-S engine of any model. I see some mention of the reduction assy. being removed by the Brits and an development of a cover plate and prop drive adaptor which enabled the engines to be run in a direct-drive mode. Too bad we can't go back a few years and ask some questions. I am always impatient with the emphasis on "Ace-istics" which has always cost us- over the last eight decades the knowledge we might have acquired from the technical types who waged a mighty- and most interesting- war of their own! Maybe it's not too late to get a N-28 wing into a wind tunnel? I'm going to comment on that thread when I get a moment or two. Have a great 2001!....... Lee
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