The Freewing Spirit model that I got from Hobby King came in a tractor configuration with a 2621 1100kv motor and an 8×5 folding propeller. I have only played with it on 2S batteries, and it has enough power to fly around smoothly that way. You might need 3S batteries to get really strong performance. But I broke my propeller and have not been able to fly for a while.
I have been getting parts to convert the model to a pusher configuration. To fit inside the motor nacelle, the pusher motor should be 22mm in diameter or perhaps a tad more. The recommended motor is a “2226-2200kv” motor, and I found it available at rc-castle.com. And here is the bundled 5×4.5 pusher propeller too.
Unfortunately, I could not find stats for the recommended motor! I actually ordered a different motor for this purpose from RC Timer, the BC1712-13 2000kv, weighing 32g. It fits into the nacelle just right and looks like it should work well. But it is slightly lower kv than the recommended 2200. It also has a 1/8″ (3.17mm) smooth shaft instead of 3mm threaded one, like the recommended motor. This means you need a prop adapter and the bundled pusher propellers cannot be used.
Propeller choice can matter a lot, and I don’t have much knowledge here. I have bench tested the motor with a Master Airscrew 5×3 3-blade propeller and an APC 5×5 2-blade propeller. Both are nice quality, and I really like the look of the MA. But the pitch on the MA is low, it even looks like a flat airfoil at the extremeties, and it’s hard to see how this will have a lot of bite in forward flight. The 5×5 on the other hand may have too much bite — I read some reviews that this propeller shines for high speed pylon racers and the blades stall at low speed.
I bench tested wide open throttle for both with these approximate results.
So I decided on the APC 5×5. I will probably get a few more props to test.
I weighed the old motor pulled out of the nose at 40g, and another 20g for the full prop assembly. The replacement cone is weighed at 20g. And the nacelle with pusher motor and prop weighs 74g.
It is very hard to get the center of gravity in a good spot in the pusher configuration. I had to put all gear in the nose, rather than the battery bay under the wing, and also use a heavier battery than I wanted. All together the plane weighs 335g without a battery as a pusher, and 390g with battery — this is getting bloated for a small 850mm plane.
I had to flip my CC flight control board back right-side-up to make room in the bay underneath.
Enjoy the pictures of the procedure and results.
Now I need to find a chance to practice flying it some more!