An MQ-9 Story Pt.3 – Motor Mount

By Bob Kreutzer

I mounted the motor finally!

I did it the hard way so if you want to do it your way it might be best. I did get the motor and spinner mounted well enough as an assembly so the result is flyable.

I used a 3d printed spinner thanks to ‘donandthereasa’ at rcgroups. Thanks! It took some work to get it to run true but it’s worth it. The spun aluminum finish took me 3 times to even get it to this point. (still needs another try)

The tricky part was making the motor spacer. Some nice person reported that this plane needed some right thrust. (imagine that…)  So I put a tapered aluminum spacer plate between the fiberglass mount and the spinner. Matching up the thrust offset of the aluminum spacer and the motor spacer took a lot of time to get it right. The M3 x 16 screws are hard to get.

A different view. Note the long M3 x 16 mounting screws.

Pretty “tucked-in” mounting on this little motor!

If I recall I used a Cobra 3520 from Lucien at Innov8tiveDesigns.com. Nice quality motor in my opinion. That nice motor is mounted on the EXACT opposite of the nose of the aircraft. So, the weight of the battery must be accounted for in the weight-and-balance sheet. I found a 4S 2200 MaH battery to balance about right. Light motor, light battery.

The lead-in picture is the back side of a motor mount stand used for  servicing.  It was bizarre enough that I found it interesting.  (but that’s me…)