Elevator Mis-match

[TManiaci]

CF Rods work well too, anything that presents a solid straight line and minimal droop. The pair of rods should droop the same if they are equal. To mitigate gravity, you can roll it over on it's side and look down, but on a 40% you need a ladder, LOL.

This method is particularly useful in the case of ganged servos. When you have two servos on each elevator half, tuning out the binding of a pair of one half always changes the surface angle a little, which then requires going back and resetting center and endpoints again. It's a process of iteration to get it right.

In this install, I have two pairs of Futaba S9156. I can see a slight repeatabillity error with this rig. The Futaba's don't hit the exact same spot every time, and if you wiggle the stick, they get back together. When you can see the servo resolution, you know you are getting down to the nitty-gritty precision the system is capable of.

[Flatlandman]

I do very similar to that Tmaniaci

I do set one side ele with a throw meter then match the other side with the sticks and i also point the 2 sticks behind the rudder with the 2 meeting with only 1/4" space between them. their more like 20"s long tho. With this method your a slave to the ele surface being straight.

[borealnw]

Getting the 9303 this weekend. Today shipped my servo's off to be serviced. I noted that they travel and different speeds will see what the tech says. In the mean time I am going over the geometery, horns to hidge line, 90* and such will post some pics see if you guys can spot anyting I might be missing.

[borealnw]

Update. Yahoo fixed it Well all that work and awesome education from all. Thanks so much for your help and all the great information on this problem. I went through the entire geometry of the linkage matched everything and a few days of work. I gave up sent my hitechs in and they found a bad motor on one of the servo's. Got them back put them in went through and readjusted and still no joy. Anyway last week was down at my local hobby store purchasing some more servo's for another project and they were out of 7985's. They had shipment of brand new Spectrum A6030's with Titanuim gears that just came in. So I brought them home and hooked up the linkage and boom dead on center and dead on travel at any position to the end points. I also have to say these servo's are smooth compared to the hitechs. Oh also did not purchase the 9303 so I was able to fix the porblem with the DX-7.

[bodywerks]

	Quote:
	It's the servos. Had the same problem with Hitec5945's and 5955's. Removed them and installed 8611's and the problem went away.

	Quote:
	I would bet the two servos are just not responding identically

Told ya! Glad you got it figured out...

[Reeseman9]

Glad to see some resolution to the problem. I am fairly new to the hobby and have read as much as I could about matching geometries. Discovered on my own about the arm position not always being 90 to the case, especially in a smaller plane with dual elevator servos in the middle of the fuse (Seagull 90 Ultimate).

I am going big now and have always used the 9303 programming for combining the elevator halves. I've heard about mixing lag and reversing y center floating. I was curious as to why I haven't seen much on reversing a servo. I was also wondering if anybody takes the time to adjust the servo pot for center point of the arm versus sub-trim or linkage adjustment. I have found that I lose some travel when doing the trimming because the splines of two servos don't match or am I missing something?

Thanks for all the great information posted and any more. Hope this isn't what they call hi-jacking a thread but it seemed pertinent.

[borealnw]

Hi jacking not at all. Ask away. I found some very nice folks here and they have been helpful.

Since this post I to have not been using much trim or sub trim to set up servos. I've been adjusting everything mechanically and through geometry over using my (now 9503). In fact on my new 35% Everthing but the throttle servo is zeroed out on the TX. I've gotten the servo's very close mechanically then using a Smart-Fly EQ10 to center and adjust endpoints. I no longer use hitech servo's on my elev halfs. I have experimented with the following 7985's 5645's and recent 7955's and out of those six servo's NONE of them matched in speed to be accurate at all deflection angles. Another words in my mind it does not mean a hill of beans if you get center and both up and down endpoints. In IMAC you need accurate in all angles. not just in striaght and level and all out 3D with elev fully deflected. You need them to be spot on 4* 10* and so on. If not then you are fighting the sticks to keep the plane flying in a straight line. So I now use Spectrum 6030's and have two sets and they travel the same distance at the same speed spot on all the time. I do run hitech on my other surfaces but on my 35% I've been toying with changing out the ailerons as well.

[Reeseman9]

Thanks, I have been looking at those, the other unit is the powersystem eq6. Just a thought, when you talk about precision and not all radios having the same output times from two channels, could you y from the receiver to two of the eq10 inputs and not have to mix channels in the radio. I guess you might lose some redundancy but would it not give you more precision? Didn't know if anybody has tried this.

[Reeseman9]

Duhh! I just went through the manuals for the eq10 and saw what I was asking was noobish. Looks like I need to save my thoughts. I didn't realize each servo output could be programmed seperately.

I've been flying just over a year and came across a deal on some planes. a 1.60 World Models Extra, 2 GP Pattys and a 90" Edge 540 w/G62. The two Pattys are airframe only and the 1.60 Extra has hitecs. I had a hard time lining up the elevators and saw what you were talking about. I've got them close enough for my flying skills. Just wanted to set up the other planes up correctly from the start. The Edge came with Tower Hobbies ts-70s with power coming from a 4 cell 1100mah battery!!?? I have a123s to go in it and am working on the rest, from what I've read here I now have a good direction to go. Thanks.

[husker]

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