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Old Dec 22, 2012, 10:44 PM
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Alan Cocconi has created the ultimate servo for the K2m (and most F3F/B/J planes for that matter)! He made a MKS DS6125 based servo that has 1.6x the torque, runs on any voltage you want, has fully programmable rotation, moves at about 0.06sec/60deg, and has circuitry that prevents you from ever burning up the motor even if the servo is stalled for hours on end! That is the ULTIMATE SERVO! I'm looking forward to the day when these are widely available!!!

Until then, I think you'd be hard pressed to do better than standard MKS DS6125 on all surfaces running on a 4cell Nimh pack. Put them in the Smartmodel frames with external bearings with aluminum arms and you have my setup for all-out speed attempts.

One step down would be to use MKS without the bearing frames. They're probably not absolutely necessary just a very nice touch if you elect to use them.

My next approach would be if you already have some DS378/398/388 then they would be a good alternative and shouldn't cause any problems. Not as easy of a fit in the aileron bay but still doable. I think you trade a little precision and geartrain/bearing tightness for a little more torque. But if you're buying new servos, then theres not really any major savings to be had going that route.

Next stop is the Hitec HS7115th. Again not a big money saver but they are certainly easier to fit inside. I do worry about the small geartrains on bad landings, and the lower torque at high loads or in rough air... I recon that they would be good to 350mph if you install them with the Fu Fix external bearings.

Last choice would be hitec 5125mg or Hyperion DS095fmd. But, people often complain about the long term viability of either of these, so you have to wonder if you're really saving any money in the long term.

Theres no doubt some other choices that I'm forgetting so let me know if you guys are aware of any other thin (10-11mm) servos that we should be considering.

I'm really pleased with the K2m! I got to fly my medium weight (85oz) version at Weldon last week in some decent air (25-36mph) and got something like 358mph. Considerably better speed for the wind than I've become accustomed to. Seems the 10x multiple historically has become harder and harder to achieve as the speeds increase but not the case on that day with that plane... Couldn't be happier! Did I mention that the K2m really LOVES to be flown hard??!!

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