John in CR wrote:Doc,
My pic is of the left side cover, not the right side. The way you're explaining can't work. Let me help the centrifugal fan thing click for you, because the angle of the holes only help the flow occur, they don't create the flow. Trying to scoop air into the motor at the perimeter and exhaust near the axle would work poorly if at all, because you would be trying to fight against the centrifugal force of the spinning air inside.
Think about a ball on the end of a string, and swing the ball in a big circle using the string. The ball pulls outward due to centrifugal force, because the ball has mass. Air has mass too, not a lot, but it has mass. When we spin that air in a circle inside our hubmotors it tries to fly to the perimeter due to centrifugal force. That's what creates the flow in all centrifugal fans. That's why intake holes need to be closer to the center where the interior air pressure is lowest, and exhaust holes at the perimeter.
The shape of the holes as presented to the outside world are that way so the wind blowing across the surface of the motor on the outside doesn't fight against the centrifugal flow created by the inside of the motor acting like a centrifugal fan. Air doesn't enter the intake holes because we scooped it in. It flows in because the air pressure is lowest at the center, since the air inside starts spinning and is flung to the perimeter and out. Fresh air naturally flows into the intake.
I hope I explained it well, because it's critical to getting the most out of our hub motor ventilation without going to some kind of blower.
John, I perfectly understand what you explain. That now make sense to me, but when i look at the picture you shown, i just miss interpreted the direction...
OOpss.. I realised that i just did the holes in teh wrong direction on my 5303 last night...
Now.. time to evaluate if i can swap the side cover of an X5 motor....with some... "minor" mod to the freewheel and disk brake side....... probably i'll need to order a new freewheel side cover... DOHHH !!!