After running this motor to hard outside, I managed to burn the motor. You can see pictures of the “burnt” motor in the gallery below.

First of all I opened the motor to take a look noticing protective isolation layer on the copper were melted. Not so strange, because when I approaced the motor after the plane fell from the sky, it was insane hot.

Before removing all wire I measured the wire diameter to 0,30mm. I found this king of wire inside very small tranformators in a computer power supply.

By using this picutre, found on this page. I was able to re wound the motor.

I actually did wound all the poles at the same time, well, one by one, but all three wires were in use, if you follow.

After finish wounding I had to connect wires together to make only three wires, brush less motor has three out wires.

Since it`s a pretty fast motor I made a delta hookup, but I did a mistake at first. This motor should have around 195mOhm per 14-turn, maybe I did not mention it is a 14-turn motor. Which means each pole (there are nine here) needs 14 turns of isolated copper wire and in a small motor like this one, it`s not that easy. Anyway, by hooking up wrong end`s I broke a ESC of mine ($10) so I had to buy another one.

The motor works just great now and I might add a video later.

Gallery

Fixing brushless motor

I’ve have been building this plane in parallel with the F22. Extra 300 is a free PDF-plane from rcpowers.com

The idea with this plane is to use a motor with variable pitch. These setups are rare and a bit more expensive than other powers systems. I will also have to install another servo to be able to change the pitch rate on the prop. 4D motor features a hollow motor shaft and I bought a set from hobby-lobby.com some weeks ago. The motor mount coming with this motor is designed for 3mm depron and I’m using 6mm depron. This is my first real problem on this plane so far. Will probably grind the front down to 3mm to be able to mouting the motor.

Update: the 4D motor were to weak for this plane and failed pretty quick. It`s now run as a pure 3D plane, even as this it`s way to flexible. I should have stiffened it of with more carbon.

Another mistake I did was making the plane in 105% size, 5% bigger than the orginal. If I were to build this again it would be 80%.

View all pictures of the plane below.

Extra 300