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Servo travel

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  • Servo travel

    Hi. My browser is slow, so i wasnt able to do a good search for this on the forums here. I will be replacing the 9 g plastic rudder and elevator servos on a dynam bf110 and want to know about getting the right travel. Ive found 13g mg servos with 270 degrees of travel, as well as 180 degree ones. Many dont say in descriptions. The travel seems to be less than 90 degree on the origi al ones. What degree travel should i look for? Perhaps they are adjustable? Do i do this in the servo travel settings on my tx? I am using an older dsmx spektrum dx6i tx and an ar 636 rx. Thank you. Fly onward. Oh also, are servos any standard drop in replacement sized? Im not wanting to do a lot of cutting and positioning away from the originals.

  • #2
    First, if the travel on the stock servo is enough, no need to go much more than that. Consider that those 180 and 270 degree servos will NOT actual be able do the full travel as most servo mounts recess the servo such that the arm will hit the foam at each end. 270 for normal control surface is ridiculous. Think about it ................ once you get past the end limit at 180 degrees, your control surface will start to move back the way it came. You don't need nor can most control surface servos operate near 180 degrees. Don't worry so much about travel. Any standard 9g servo will give you what you need for that plane.
    Servos are "adjustable" in the sense that you can set the travel limits in the servo menu. Then you can limit them even more with "rates".
    Servos are not a universal size. You need to measure your stock servos and compare to the dimensions of the ones you'd like to buy. On the most part micro servos in the 9g size will be very close in size from one brand to another so long as you're getting known brands.
    Rather than looking at 13g servos when you've had 9g servos, ask yourself if you really need higher than 9g. Did the old servos seem to have the strength to do the job? Is so, stick with 9g. If you do want to go bigger servos, check the physical size to make sure they'll drop in.
    What you might consider more so than changing size, is to look at metal geared servos. They'll be stronger and less easily stripped.
    Then there are normal and reversed servos. Make sure you're getting same kind as what you are replacing.
    Finally, find out if your plane has analog or digital servos. Try to stay with the same type.


    • #3
      Thanks so much. Ive watched brian phillips 4 hr build/fly video on this plane, and the geometry is such that the servos tend to bind. The dual rudder setup is a little complex. Also, because of the angles, the pushrods can bind up, possibly overpowering the servos. It just needs to be a better design. So his recommendation, even before he flew it, was to change to 13g metal gear servoz, after observing the linkage and movement of the rudder and aileron servos. This is a 1.5 meter plane, and in his flight test, and others, the rudders just dont have a lot of authority. Ill consider using metal gear 9 gram as replacements, as what you say makes sense. Im trying to assemble this plane to perfection as much as possible, and account for future possible problems. Im going to do other small mods to make it more reliable and functional, well before maiden...esc cooling, rx mounting, gear reinforcement, and a couple others.

      I knew the 270 servos were way over, as well as the 180 ones. But thanks for confirming that i can set the travels in my dx6i menu. I had a dx6i in the past, love loved it, but couldnt remember about settings for servo travel. Ive ordered another used one at a very good price, and i will also have the manual to confirm and walk me through.

      Some of the servos have measurements given, so i will definitely confirm before ordering. Thank you.