BF109Z

Twin 109 with wingspan 1.2m. Setting : CC/CW 7030 prop. Slightly underpower with total current ~20A @3s.
The Emax motor has QC problem as you can hardly get any same kv motor, despite the label is the same. My first pair was found to have significant different current drawn (12A vs 22A). End up by purchasing another Emax. Lucky enough the kv is now matched with current drawn 12A vs 10A.

The C.G. with 2200mAh 3s Lipo can only be met by installing the BL outside the motor mount. The stock landing gear is quite soft. Will soon install retractable gear soon. It looks extremely scale in the sky. Since it is slight underpower with a low kv BL (1000kv),>

Flying character is quite different from other WWII fighter. In strong crosswind laning, the rudder can help very much as the aileron is not too sensitive, as the center of mass is far from center.

Freewing 3900kv EDF inrunner death

Freewing F35 stock 3900kv motor suddenly stopped in air. Luckily the plane landed safely. The ESC did not smell and likely the motor is burnt. Infra-red temp. measured >110 deg Cel.

The motor was found seized and postmortum was undertaken. Opening the can and the wires coating was found melted and seized the magnet. Distal third of the magnet is partially demagnetized (where the heat sink does not go that far).

Lesson to learn: Let the motor cool down before another flight! Especailly if the inrunner is aging.

Comparing high power EDF Brushless

Lt to Rt: 64mm EDF 4800kv SAPAC, 70mm EDF 3200kv 2842 SAPAC, 64mm EDF 3800kv Freewing.

The freewing has longer stator and thinner plate (0.18mm?). Their magnet seems to come from the same source and strength. Interesting, the SAPAC has lots of cogging.

Dynamically balanced?

2842 - Inside as well?

Rewind JustgoFly 500T Brushless

My JGF 500T (2000kv) has been a very powerful motor of high torque and low temp. After years of abuse, it died with core/stator melt down and burnt my cc35.
The stator is completely rewind with 14 strands 0.23mm in 5T.

Small amount of epoxy is used to hold the wires in place. Tested with 6x4e at 4s , current ~35A. rpm....forgot....Not bad.

The stock neodym magnets are still very strong !

One comment is the shaft is not replaceable. Mine got bent on a few occasions after crash, and needed to be straightened with some skill.....

BF109Z Zwilling Germany

This Twin 109 has never flied during WWII.

Building in progress....

TWM Voodoo P51 with retracble gear

Pre-installed retractable gear.
The pattern is nice looking. The only comment is the leading edge of the wing is not manufactured with balsa to make it smooth enough. The ridge of the spar is obvious here.

The battery tray allow easy access for battery change. The old version(not Voodoo) P51 does not have this latch/ battery compartment access ,and have to detach the wing after each flight.

Very light weight. Very manoeverable/ predictable and easy to built. Cheaper than foamy as well!

Repairing and Upgrading Phoenix CC35 ESC to 45A

2 FETs burnt in the front and 1 FET at the back.

A new FET is soldered to the back. Spare spaces available to upgrade to cc45.

My CC35 has served me many years as a reliable ESC. The soft start and high current cut programme has been working perfectly. The only downside is the onboard BEC is too weak and on 4s, you can barely plug in 2 mini servos, even so the BEC gets very hot.

Recently my JGF 500T (at 4s@40A) meltdown the stator core after I continuous fly my F16 at over 170kph. The high current surge burnt 3 FET (IRF 7832) on the CC35 ESC board.
Most of the time FET will burnt in a closed circuit with the In/Out pins shorted. Sometimes the single Gate pin will short as well.

I try to fix it , tools needed:
1) replace with some cheap IRF 7832 (cost~HKD $3 only)
2) 100W solder gun, best with temp. control., or blow torch soldering
3) Desoldering wire ( To clean any excess solder left on the board
4) Ohmmeter- to check for short circuit.


1) Remove all burnt FETs, usually complete row of a single polarity is burnt.
DO NOT BRUTE FORCE BY PRYING IT, OR USE TOO HIGH TEMP SOLDERING GUN TO TAKE IT OUT.
I use metal cutter to shear away the top of the FET, then carefully remove the pin with soldering gun. Clean any excessive solder with desoldering wire.
2) Check for short circuit or continuity of the board. Input -- Output - Gate
3) Apply flux on the new FET, to ensure a true soldering point.
4) Apply some glue to the back of the FET to stick it into correct place. (or anyway U can think of)
5) Press lightly on the FET (with a forcep) and apply solder. Be careful to limit the soldering time less than 2 seconds.
6) I test the ESC with a motor after soldering of each FET.
7) Finally I add another 6 FET to Upgrade it to 45A!