ORIGINAL: fiery
Martin
Many years ago I had an MDS 3.5 cc aero diesel. It's head fins were like that from the factory. I regret trading it. Heavy, but powerful.
The prop wash spirals around the engine. Arguably the orientation of the fins as shown above is, if anything, better for cooling.
And if the engine is cowled?
Nah, Ithink that if angled was best it would have adopted a long time ago.