3 Version of Towerpro Metal Gear 995

Left - old version with overshoot
Right - newer version.
photo from blood keith blog

SAPAC L39 70mm EDF

L39 is a very stable, yet agile aircraft. Their are ample space to install lots of stuff, including battery, lighting, retracts, etc. The L39 has the same wingspan as my 90mm F18.

The wing is detachable and needs close attention. The wing is only secured by a single 2.5mm screw. My friend's L39 has its wing completed detached from the fuselage during hard landing. I strengthen it with 2 additional 3mm screw mounted on the side .

Viper vs A4

Both have similar power and powered by 3300mAh 4s @70A.
A4 is smaller and it accelerates faster.
Viper has flaps that makes it much easier to land at lower speed.

F18 90mm EDF midair collision with 1.5m glider

Midair collision with another glider , results in the nose being sliced. The glider crashed but my F18 land safetly. That is a clean cut and she is fixed right away.

Lucky maiden for my A4 Skyhawk

Harvesting the 3mm EDF fan adapter from old J-power EDF

The stock motor rated at 250W and has to be replaced by current powerful >520W BL. I have to "harvest" the pressed fit adapter from the old motor. This is a very difficult procedure without the right tool. I use 2 piece of 5mm shaft (from Trex 450) and a bearing remover to press against a 3mm steel screw inside the 4mm hole on the adapter.

Happy Easter- unlimited flying everyday

2 incidents result in emergency landing.

This is the second time my rafale suddenly cut out power. Last time results in belly landing without damage. Not having investigate the cause, she was put on air again. While doing a low level inverted flight, the cut in happens again. Luckily, she can be recovered from an inverted roll at 3 feet height and land safely.
The root cause is the Hoffman Magnetic ends its life, despite she was kept at 70A @4s. Luckily my cheap 120A ESC does not burnt and the on board BEC does not lock out.

My F35 somehow sqeak midair after a "pop".

Opening the housing and reveal a 3mm screw was somehow suck into the EDF ?? Where does it come from, after 2 mins flight??

OK Model Type2 70mm EDF

The housing is FG reinforced and is very tought. The design is great to allow more cool air to contact with the inrunner case.

The Type 2 fan is not well balance at first glance. However, I was wrong and find that the vibration is even more significant after static balancing.
I end up leave the stock fan intact and it runs smooth and vibration free.

The Tamazo inrunner is very good quality and the copper wire is wound round stator (Unlike cheap inrunner). The magnet is very strong as well. Unfortunately the case is pinned and is almost impossible to disassemble to take a good look inside.

Don't say "One more flight"

The Hobbywing 40A ESC has a switching BEC board over the FET circuit. The 2 circuit board is soldered together, so increase the difficulty to repair components between.

Capacitor burst on crash. This is easy to be overlooked if the heat shrink is not cut open for investigation after a crash.


The specification of 40A is damn correct. I abuse it at 50A and the metal heat sink melt the heat shrink and shut down the BEC. The FET itself shutdown and protect from overcurrent.

A 50 cent repair.

ChangeSun Electronic Retract Crash resistance

Nose dive crash results in complete destruction of the fuselage. This electronic retract proved to have high crash resistance. Only the servo wire is torn. Look inside the large brushed motor and the metal gears.

Solder the wires and the electronic retract back into services. Note that the worm gear has bearing that gurantee smooth operation. The control board has silicon coating that protect the circuit from water and erosions.