In all my recent builds I’ve used Chocomotion servos (supplied by www.leomotion.com) in combination with the IDS system supplied by Servorahmen.de. When deciding to install the IDS system, we’ve found that 1) you need good and strong servos; and 2) at ridiculously high speeds even the strongest servo may give up as the lever from the IDS system is simply too short. In our earlier builds we used Futaba 3174 and KST x08 (aileron) wing servos. Unfortunately I’ve had quite a few serious burn-outs and control surface flutter at speeds over 240kmh on my scratch-built Diana2, even resulting in one Futaba servo catching fire (fortunately the plane is still alive!).
The Chocomotion servos are much stronger than the Futabas (no breakage so far, and the newer versions now also have little or no play). For the Urupema’s flaps and flaperons we use the Chocomotion 10/10, as with our JS3. For the ailerons we’re for the first time using the Chocomotion 8/6 instead of the KST X08. The “normal” X08 is simply not strong enough for the ailerons using IDS in larger planes when you want to fly it fast (I’ve killed way too many of those…an they’re not cheap). The X08plus is much better (no breakage so far), but in view of our good experience with the Chocomotion brand, we decided to try out the Chocomotion 8.0/6.0 instead, as it should be a bit more powerful than the X08plus.
As we have quite large control surfaces on the Urupema, we also decided to replace the standard control horns on the control surfaces with our own, using a bigger lever to reduce stress on the servos. It was quite a bit of work to cut them out of glass board (by hand), but I hope that it will allow the servos to hold at higher speeds.