It's got a solid metal hub. Greg, does yours have a clutch? I'm thinking that might be a nice addition, so the fan doesn't draw engine power when not needed. Imagine that - having some extra power on tap in a 240D! OTOH, this being sunny Florida, the clutch would be engaged most of the time anyway.
I'm not in fear of the engine overheating, now that the electric fan is working. And I have plans to change the coolant and clean the exterior of the radiator while I'm there. I was just hoping for some comment on the apparent lack of ram air effect.