Well, it was before my time. :) But, in those days they were experimenting with different airplane engine designs.

Cooling was obviously not a problem. In fact there was a cowling over the upper 2/3 or so of the Fokker engine. Fuel distribution was relatively easy and went through the hollow crankshaft. There was no throttle, so one had to simply interrupt the fuel flow for speed control. The engine's flywheel effect kept things going. Listening to that on the ground the first time, is a bit disconcerting. The Fokker, I remember, had a 2 cycle engine, which helps with the power to weight ratio. Castor oil was mixed in with the fuel for lubrication.

The engine's gyroscopic effect stabilized the plane in flight. But, if you read the Sopwith Camel link, made take-offs tricky.