Hi guys!
I'm designing an aluminium prop hub for my 40cc. Now, I just need to know the exact diameter of the prop hub (the distance between both "║") of a 20, 22" or whatever prop this engine may swing, the inner diameter (the "O") and thickness. Does it change if the prop is 2-bladed, 3-bladed, etc?
Thanks for your input, I hope this poor diagram explains something

Prop (front)
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/ \ | |
║ O ║ =? |||||| ] = ?
\ / | |
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