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Old 07-27-2019, 01:44 PM
SBrock is offline
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Question
Control Surface/Servo Resolution

First full disclosure, started this thread in the wrong forum (IMAC), moving over here.

Setting up a new plane for IMAC (no 3D at all) and have a question on surface throws/servo resolution. Have programmed the Hitec servos for end points and centering, also happy with the mechanical setup (short servo arm, longer control arm). Also set the DX9 TX at about 140 for initial travel setup.

Iím getting about twice the control surface throw that I want and using the dual rate function its taking about 50% to reduce it to what I want and Iím not clear if Iím losing servo resolution doing it that way. Could get a little reduction by changing the mechanical setup but not near enough.

So the question is, what is the correct/best way to solve this and keep servo resolution high? Reset the servo end points with the programmer to reduce throw? Use the TX end point function and reduce the throw that way? Thanks in advance for feedback.
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Old 07-27-2019, 01:58 PM
BarracudaHockey is offline
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TBH I felt it was more appropriate there but that answer doesn't change.

Shorten the arms and raise the rates.
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Old 07-27-2019, 02:15 PM
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What are the length of your arms and control horn? A typical IMAC setup is 1in arms and 1in control horns. This will give you the best mechanical advantage.

What was the issue with posting it on the IMAC site?
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Old 07-27-2019, 08:06 PM
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No issue, after thinking about it some I thought it seemed to be more of a radio/servo question.

With the current setup I'm at 1.5" for arms and control horns, can get to 1.25" for each and will plan on doing that.
Just trying to decide which approach works best, reprogram the servo end points, reduce the ATV settings on the TX, or reduce the throw using dual rates.
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Old 07-27-2019, 09:52 PM
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I usually set my endpoints to Max or close to Max. 120-130ish. And I try to use the shortest arm I can get away with. It does reduce speed but increases resolution which it what I'm after. If you can get 1 1/4" spacing and still get your max throw, that is much better. Max reflection will be determined by what you think you need during trimming and sequence flying. If you find you have way more throw than necessary, change to a shorter arm.
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Old 07-28-2019, 12:55 PM
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Ideally you will need to run 1" arms or less to allow you to increase the servo movement to around 120 degrees total for the best resolution.
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Old 07-28-2019, 02:37 PM
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Shorter the arms the better resolution, torque, and less slop will be. Keep endpoints over 100. I like to set them at 120 the find the arms that get me what I want for high rate. Reducing only the dual rates if you need less won't hurt resolution. I've helped many people around here learn this and they feel new planes after. Pattern flying has really helped me learn setups
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