Motor mounts on frames

[DrAbsurd]

Are the large holes in the center of each arms motor mount area for access to the lock nut or to remove heat from the bearing?

 

[holtneil]

Its because some motors had motor shafts sticking out of the bottom of motor as well top so a hole was needed in the mounting plate all bearing cooling should be with air flow over the motor case of you look at Helicopter motors they have a cooling fan cut into the bottom of the motor as they are under a canopy need extra cooling