Syma S107 mods – the Terminator edition

S107, Terminator edition

The Syma S107 is a remarkable little RC heli – despite some possible quality issues in recent times. It is very robust, stable and easy to fly – exceptional value at around AU$30 delivered. Of course, what is really lacking is insanity, so here’s how I went about turning it into an unstable, twitchy and fast monster.

Weight savings is where it’s all at I reckon. Fitting a more powerful tail motor might help, but it is extra weight and power. I instead focussed on stripping as much weight as possible, and shifting weight bias forward for increased forward speed, at the expense of rear speed (or even stable hovering!).

Here’s where I saved the weight:

  • Removed undercarriage (1.91g)
  • Removed tail brace (1.20g)
  • Removed tail rudder (0.44)
  • Remove nose cone, weight and led (3.26g)

I also shifted the battery as far forward as possible. One other weight saving was trimming down the balance bar weights. Unfortunately the new S107’s don’t have removable weights like the originals did. Instead, I cut a small section off the end of the weight. Not sure on the exact weight, but since it is rotating mass, it makes a huge difference in rotor acceleration. Stability is affected, however I see this as a positive since it gives more twitchiness.

A total saving of approximately 6.8g. With an approximate stock weight of 38.3g, this gives a saving of around 17.7% – very, very noticable. Hovering can be achieved at around 1/3 throttle (instead of around 2/3 stock), and banked turns are possible due to the increased forward speed. Highly recommended mods once you get the hang of the stock S107 and are looking for a bit of insanity.


Syma S107 problems – bad batch of gears?

All three Syma S107 helis I purchased recently from have had issues – the intermediate rear gear (for the top rotor) have suffered from broken teeth, and there was one motor failure (front, drives the lower rotor). The dead motor I think can be chalked up to bad luck, but the gears I think might indicate some larger quality issues in what has up until now been a fantasticly robust and value for money rc heli.

Location of intermediate gear with broken teetch

Syma s107 intermediate gear with broken teeth

I’ve contacted but so far they don’t seem keen to send replacement gears. Luckily ebay seems to be a good source (search for “s107-09”) – probably not a bad idea to have some spares handy.