Oh, and just as a point of interest, we've got a couple of these functional engines living down the road from us. There's a museum where they either restore planes (WWII) or reconstruct them (WWI) and fly them. There are over thirty types from both wars including four repro Fokker DR.1 Dreideckers and an E.111 (variant of the Eindecker). There's a Rotex replica rotary in one of the DR.1s. They don't mention that Werner Voss' blue Dr.1 is also modeled.
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Bob