I would take note that the ribs on the inside of the cover are probably reinforcements, and I'd work around them. I'd put vents nearer to the axle on the non-drive side and out at the perimeter on the drive side
I worked nights at McDonnel Douglas, and we had a lot of time to kill just chatting. One example is the landing gear of a new C-17 cargo plane. It was fitted to a cube-like framework, and it began raising and lowering 24 hrs a day. If the hydraulics sprang a leak, I stopped the cycling, fixed the leak, started the cycling back up, and cleaned up the mess. I was allowed to read and talk, but not sleep.
I am not an engineer, but I've had a lifelong fascination with mechanical devices of all types, and many long conversations with mechanical engineers at McD's and also at Sargent Hydraulics (submarine hydraulic components).
I agree, Chalo. Don't cut through the reinforcing ribs, I see three of them that are cut. I can stand my 200-lbs of body on a single aluminum soda can, if I carefully climb aboard and apply my weight gently and evenly across the top. Then, if I pick up that same soda can, I can collapse the sides quite easily with two fingers. The aluminum can will survive 200-lb of load stress in one direction, but is very weak from another direction.
Also, I'd suggest that the holes are too large. Add a temp sensor, and start with smaller holes...you can always make them larger. I also don't like the squared-off corners of the holes next to the rim. They should also be round to eliminate stress-risers. Just a thought...
I think you'd be surprised at how much flow you can get (even with smaller holes) using a centrifugal fan, such as this (the common model for this is a ventilated front brake disc for an automobile...it works):
https://endless-sphere.com/forums/viewto ... 30&t=62658