No, not an air intake. Just a hole. The aerodynamics weren't really all that draggy. Compared to the "capped" spinners the difference was all of 1-2 mph I think. I think part of it was a German cultural thing. You look at a lot of their prewar designs, even those with no hope of a central prop gun, etc, and you'll find a lot of blunt props. More a throwback to 1930s times, and older prop design, I think. They moved past it, but it took time.