Fokker E.III

16 October 2017

It got flying last Sunday. Throttle was between 30-50% for level flight and there was not much difference in airspeed in anything beyond.

The wings twist easily, if there were 2 spars it would behave better. A wheel was lost and the thin ply undercarriage broke.

It was fun building, it flies but need careful trimming (wing twisting), don't see how I can improve its performance by reducing noseweight as it wasn't forgiving.

13 October 2017 (Response to Wijarso)

Hi Wijarso,

Nice to hear from you again. My current software setup doesn't allow me to reply you in the usual manner, so I am doing it here until I can get it fixed.

Yes, it is tail heavy: the tail moment is long, the elevator surfaces small, the nose is short and the CG is required to be located at the spar. I added quite a lot of additional noseweight and I mounted the cell further front at the nose (just above the geared motor, the instructions had the cell behind the firewall) to bring the CG to the spar position. I will probably move the CG back to get better performance after removing some noseweight but that has to be after a safe flight.

This is not a slow flyer for small indoor venues. I don't think a 3gm or 5gm motor will help. Maybe a heavier motor, say a 10gm that can spin a 5030 directly on 1S (I don't suppose you have a geared brushless of this size) is better. The additional weight of the motor can replace the noseweight that is needed otherwise! That said, I quite doubt it. If you need a separate 3A/6A ESC, you might find you don't have the space to mount it conveniently and at the correct location. And think about the cell you will need to power the ESC and motor! (or worse still, a 2s battery!) There isn't much usable space in the model.

Whatever you try, be careful of weight; do try to keep its AUW as light as possible. My model's AUW is about 55gm, and it will not turn in a good performance. If yours turns out heavier, yours will have to fly much faster if at all and the wings may be twisting all over the place.

Regards,
Keng Hua

9 October 2017

I spent a lot of time to change the geared motor. I started with the assembly of the 0820 geared set and it didn't spin at all, then I tried the WLToys' geared set and faced more difficulties, and finally I crashed it on the first test fly after having driven 10-20km to the field.

• The 2 brass bushing are very accurate and the shaft is not true, I tweaked the seating and the shaft and it wasn't possible to have free spin! So I used only 1 brass bushing and that seems to work.
• Before soldering the connector, I saw one WLToys' geared prop/motor lying about, so I hotglued and connected it to the board. But the motor did not spin! I removed the board thinking it was a faulty board because I plugged in another motor set and that didn't spin either.
• It turned out that I had bent connector pins on the board and the board is fine but the 'original' motor was faulty! I glued back the board and geared prop/motor after replacing with a new pinion geared motor. Everything seems nice, ready for test fly.
• Early Sunday went to the field and managed only one short test flight. There was enough power for flight although elevator was set too high and rudder has not enough right to counter the torque. The test flight ended when the Fokker E.III entered into a stall and smacked straight into the ground.
• The propeller snapped and I couldn't perform another test flight.

WLToys' propeller is very resilient, so it was bad luck that it crashed so perfectly to snap a blade.

21 September 2017

Before crash

Maltese Cross

I bought a kit with motor from Banggood.

The box was crushed but the kit was fine, the balsa only suffered minor depressions. The ply pieces were warped, so it was water spraying and twisting to straighten them out as much as possible. I trial fitted the parts and trimmed the high spots with a few strokes of a 200 grit sanding block. I did not follow the exact assembly sequence as illustrated in the manual, especially the motor mount, pushrod installation and the main landing gear. The straightened landing gear ply pieces were assembled and glued, then the warp was corrected and the whole glued to the model. My vertical rudder was tissued and painted both sides and this caused a rearward shift of the CG (long tail, short nose, didn't realized it would be that bad). I added a heavy ball bearing to bring forward the CG to the spar, consistent with the manual.

The supplied geared motor (0716) did not have enough oomph (that or my worn out lipo compounded by the heavier model or it could be the bent shaft (I wasn't careful). The model glided forward but heavily to the grass field at full throttle. The ply tongue to receive the nylon motor gear mount broke. I will need to fabricate a wire mount and I will try a different lipo cell.

Kit was assembled with superglue throughout, I used WLToys' receiver board (hot glued as far forward as possible) and a 200mah lipo cell. Tools required are: NT cutter, sanding block and soldering kit for the motor plug. Decoration: generally plain, except some parts which are painted with acrylic paint and my maltese crosses were made with tracing paper and black gel pen.

Overall, it is good fun. Mine took longer than I thought it would but I like it even if my first test flight was not successful. My suggestions to the kit producer/manufacturer is to include a short assembly instruction of the geared motor (not everybody knows how to correctly assemble an efficient geared motor set without bending the shaft), or to supply assembled, and perhaps to use a bigger/longer motor for better thrust.