With the servos mounted in the fuse, you don't want the servos at 90º to the surface/servo case. First off, because you will get a ton of down elevator travel, and little up. So actually, you need to angle the arms on the servos one to two gears forward (towards the nose of the airplane). This allows you to get equal travel up/down.
Just as Joe said:
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I 2nd the using all the end point you have. But before you get into the tx programming, I'd match the linkages mechanically: Slap some little paper protractors on the 2 servos and 2 surfaces. With no power move the elevator halves from center to +45 then -45 degrees (or whatever your 3D max throws are). Observe how far the servo arm moves. The servo should move exactly the same + and - from the elevator half neutral position (+55/-55 degrees for example). Adjust the push rod length to get the +/- to be equal. After all this you may see that one servo is 52/52 and the other 55/55. To get both halves equal adjust the horn height on one of them. Once you get a setup that is for example: surfaces 45/45, 45/45, servos 55/55, 55/55 then you can move onto programming the servo using the hitec programmer, a matchbox or equalizer. Or you can do what I do and just use the tx subtrim and end points. Yes it actually works. You use the sub trim and massage the end points to act as the servo programmer, matchbox/equalizer. As long as you have them mechanically synch'd this works. I'm only talking about one servo per elevator half here. Ganged servos are another story. If I could show you a video of two 50cc 3D planes that I have setup this way, you would not be able to see any difference in the speed or positions of the two elevator halves. I should actually make one since I see this problem come up all the time. |
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This should get your mechanical geometry all correct.
Seth