[4stripes]

A friend asked me to dynamically balance an FMS 90mm fan for him so here are my thoughts on the product.
http://www.fmsmodel.com/fms-90mm-12-...fan-with-motor
The total setup is very light at 325g with connectors.
I think it has the smallest outrunner I have ever seen in a 90mm fan and the 1900kv rating seems incredibly high for a 12 blade rotor. That being said it needed to be disassembled as I wanted to see if the collet adapter and motor mount screws were on securely. No locktite was found and the fan came apart easily. I added locktite to the motor mount screws and placed small fiber washers under each screw. A drop of triflow oil was added to the motor bearings. I then roughened up the motor shaft with a file and cut a slot in the outer end of the adapter so that a flat blade screwdriver could be used to secure the fan nut and collet. The fan had some yellow ball of "?" jammed into the rotor from behind near the hub front. Is it a ball of yellow paper or thin cardboard, who knows, but I left it in there and simply clocked the fan. It didn't take long to find the sweet spot for smoothest running. Then I added the spinner and also clocked its position until smooth. It then needed more weight added. I used approximately 1/4" square duct tape layered twice that was stuck inside the spinner where the weight was needed. The first bits of tape are simply stuck on the outside of the spinner until the location is found then the weight is transferred inside where it will not fall out. Unfortunately I couldn't check the power but looking at the factory details I would think it pulls just over 110amps.
Overall I think it is an amazingly light setup that has plenty of potential. I did fly the same fan in a friends FW F18 and it flew well. The extra dynamic balancing will only make it better.