Thanks Mike. As Jason mentioned I did see the Diii pictures from thevintageaviator web site. And I came to much the same conclusions you summarized - specific to that model/engine. The picture shows the hole saw cutting through the jacket in the head area, surely that means fluid communication to the cylinder jacket annulus. And so the water circulation goes exactly as you described. Now there is no guarantee what Mercedes did is exactly was what BMW did, but I took this to be a good guiding principle in the absence of any other information. In fact as I thumb through my new books there appear to be slight water piping variations even among same engine brands/models, but that would make sense based on what airframe they resided in & different radiator locations.
What gave me pause to above understanding, which I posted a bit later in #8, was an excerpt from Airplane Engine Encyclopedia specific to the BMWiii. Here it is again. 'the centrifugal pump has two outlets, one leading to the bottom and one leading to the top of the end cylinders. All of the cylinder water water passages are connected together'. two outlets, that seems specific. Is this something something different to the Diii or a wording issue? This is what confused me, not the Diii. But when I look at the BMW pump pics from other documents I don't see anything obvious suggesting a second outlet at least integrated in the pump. So my guess is maybe a wording issue in the Encylopedia because I have never come across any similar elsewhere.
As mentioned, although I'm interested, I'm not particularly fussed if I ever know the BMWiii nuance, presuming there even was a nuance specific to the model. Its pretty much a given I will have no water in the head, it will be confined to the jackets. Flooding the jackets in parallel from a lower tube & collecting them in an upper tube will hopefully get the cooling job done and somewhat resemble FS in spirit. Thanks for your interest.
