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Trouble with 2 Aileron servos

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Trouble with 2 Aileron servos

Old 03-27-2010, 06:30 PM
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Trax540
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Default Trouble with 2 Aileron servos

I have a question about the setup im running, hopefully someone knows

I have 2 servos in the wing for my ailerons. Im running them into a Y harness and plugged into 1 channel. However it seems impossible to get the servo arms to be perfectly opposite to each other. Its like they are 1 click off on the gear compared to the other.
So when 1 aileron tracks full throw the other has a pinch more throw in that opposite direction, and vice versa.

The PROBLEM is that it causes 1 aileron to overthrow to far in the down position (because its the rear tapered ailerons) while the other is ok because its going up. And i cannot just use the trim for that channel, because it effects both servos.
Ive thought about sanding abit more taper in the aileron but it would be way to much to take off the back.

The radio i am using is Futaba 6ex 72mhz.

Anyone have any idea how i can fix this, im completly stumped atm.
Old 03-27-2010, 07:06 PM
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DMcQuinn
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Default RE: Trouble with 2 Aileron servos

No two servos center to the exact same spot. So even though both servos are receiving the same electronic signal from the receiver via the "Y" connector, they don't both go to exactly the same spot. The output shaft has about 25 splines on it (every brand is different). So the best you can do is to put the servo arms as close as you can get them to each other. 360/25 = 14 degrees, so the arm on one servo could be 7 degrees from the other (worst case).

What some of us do is to find a bunch of servos and try to find two that track together and use these two servos on one wing.

Another choice is to get hitec servos that can be programmed. Then you can make two servos match exactly on all three points (center and both directions).

Another choice is to buy a JR matchbox or smart-fly equalizer. It is like a "Y" connector, but you can set the center and endpoionts for each servo independently.

Another choice is to plug each aileron servo into its own channel on the receiver. The you use the transmitter programming to set each servos center (sub-trim) and endpoints (travel adj). For this you need a fancier transmitter and a receiver with lots of channels.
Old 03-27-2010, 07:32 PM
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airbusdrvr
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Default RE: Trouble with 2 Aileron servos

Another choice would be to reduce the throw(EPA-end point adjust, travel adjust, or whatever Futaba calls it). Then the aileron would not move quite so far. This subject has been discussed in other forums and I understand the concept, but could not adequately describe it. Suffice it to say that when a rotational(servo arm) movement is transmitted into a linear object(control rod), the amount of movement can differ in opposite directions.
Old 03-27-2010, 07:49 PM
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LargeScale88
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Default RE: Trouble with 2 Aileron servos



I would adjust the clevis or rod on one servo to match the other. Sense one has more movement then the other, adjust where the clevis hooks on the servo arm, or shorten or lengthen the road going from the servo to the aileron. I've got my computer radio which does the travel adjustment for me, (not sure if yours is computer), anyway, just adjust the clevis and rod.

Old 03-27-2010, 08:05 PM
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Steve Percifield
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Default RE: Trouble with 2 Aileron servos

It's probably not enough to make any difference in the air. BUT, more than likely your servos are driving from opposite sides, since they are in opposite wings. Look at the servo arms, On the 4 arm ones, each arm has a number on it close to the center. This is the degrees off 90 degrees the arm will be when mounted. Match the numbers on the drive arm and you will be close. In normal situations, you cannot get them exactly, and it doesn't really make any difference in every day flying.
Old 03-27-2010, 08:23 PM
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andrew wisc.
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Default RE: Trouble with 2 Aileron servos

as long as your not using flaps on the 6exa you can run each servo to seperate channel 1 and 6. use flaperon and adjust each servo independantly. doing it on daughters warbird. works good
Old 03-28-2010, 12:03 AM
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Default RE: Trouble with 2 Aileron servos


ORIGINAL: LargeScale88



I would adjust the clevis or rod on one servo to match the other. Sense one has more movement then the other, adjust where the clevis hooks on the servo arm, or shorten or lengthen the road going from the servo to the aileron. I've got my computer radio which does the travel adjustment for me, (not sure if yours is computer), anyway, just adjust the clevis and rod.

That. Get them approximately centered with the servo arms and then fine-tune by turning/adjusting the clevis connectors. Once they are centered the throw will be equal enough from a "Y" connector set-up.
Old 03-29-2010, 10:03 AM
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MinnFlyer
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Default RE: Trouble with 2 Aileron servos

Are you using Futaba servos?

If so, Futaba servos have the advantage of having an uneven number of splines in their output shafts, so the servo arms can be rotated so that ONE of the 4 or 6 arms will line up at 90 degrees.

Note in the diagram how the arms are numbered 1 thru 4. As the wheel is rotated to the next arm, the angle of the arms change.

All you have to do is center your servos, place a star wheel on one them and rotate the wheel until one of the arms lines up. Then, cut the others off (or leave them on if it doesn't bother you)
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