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Old Nov 30, 2012, 01:35 AM
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Help!
3 axis FBL heli: Is my servo arm and swash maladjusted?

Hi,
I just changed the pitch servo as well as arm. I powered up the servo and attached the arm so that it was horizontal to the long axis of the servo. I measured the distance between the servo arm and the connecting rod to ensure it was the same as before.

1. With the heli powered up, the swash is tilted forward (1st picture attached)

2. Now the servo arm is horizontal to the ground, but not to the long axis of the servo (2nd picture)

Do I have a problem?
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Old Nov 30, 2012, 07:42 AM
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Swashplate should be level

Quote:
Originally Posted by Lentar View Post
Hi,
I just changed the pitch servo as well as arm. I powered up the servo and attached the arm so that it was horizontal to the long axis of the servo. I measured the distance between the servo arm and the connecting rod to ensure it was the same as before.

1. With the heli powered up, the swash is tilted forward (1st picture attached)

2. Now the servo arm is horizontal to the ground, but not to the long axis of the servo (2nd picture)

Do I have a problem?
When I put on a servo I power up the heli and with the gear switch down I put the arm on as parallel to the ground as possible. Then I turn off the power and hold the arm in position while I tighten the screw so as not to strip the gears.

When powered up the swashplate on my Wasp is parallel to the ground, as I would think it should be if the 3 axis gyro is working properly. Don't know if it makes a difference, but are you sure your trim is centered?

Just checked my manual. Look on page 12. The swashplate should be level. You'll probably have to adjust the linkages.
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Last edited by Pa flyer; Nov 30, 2012 at 08:20 AM. Reason: More info
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Old Nov 30, 2012, 11:11 AM
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Originally Posted by Pa flyer View Post
Just checked my manual. Look on page 12. The swashplate should be level. You'll probably have to adjust the linkages.
Is your servo arm parallel to the ground like mine is in the picture, or is it parallel to the long axis of the servo?
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Last edited by Lentar; Nov 30, 2012 at 12:05 PM.
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Old Nov 30, 2012, 11:21 AM
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How did you level the servo arm? Did you do it from the transmitter or from the gyro? And how did you set zero pitch on the TX while you were setting it up? Did you just leave the stick in the middle or did you actually set the TX to go to zero pitch?
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Old Nov 30, 2012, 11:27 AM
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Quote:
Originally Posted by Hajile View Post
How did you level the servo arm? Did you do it from the transmitter or from the gyro? And how did you set zero pitch on the TX while you were setting it up? Did you just leave the stick in the middle or did you actually set the TX to go to zero pitch?
As you can see in the pictures I put up, my servo is not mounted horizontally. So should I level the arm to be parallel to the long axis of the servo (I have drawn a line and label on the 3rd picture to clarify what I mean by this) or to the ground horizontal (again labelled this)?
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Old Nov 30, 2012, 11:36 AM
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Quote:
Originally Posted by Hajile View Post
How did you level the servo arm? Did you do it from the transmitter or from the gyro? And how did you set zero pitch on the TX while you were setting it up?
My transmitter is fully programmable, and I set the manufacturer recommended 5 point values (which are % values) for pitch and throttle. It seems to have zero pitch at throttle mid point. To level the servo arm, I powered up the heli with the transmitter on. I then attached the servo arm to be parallel to the long axis of the servo (see the third picture with labels to see what I mean by the long axis of the servo).

I thank you for your help and interest!
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Old Nov 30, 2012, 12:33 PM
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The TX may be programmable but when using a 3 axis gyro, you can't use the trims on the TX to level it.

If you can't access the trims from the gyro, then you can't truly level the servo arms, all you can do mount them as close to the desired angle as you can, and then screw/unscrew the links to level the swashplate. All trims and subtrims on the TX must be zero.
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Old Nov 30, 2012, 12:45 PM
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Parallel to the ground,etc.

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Originally Posted by Lentar View Post
Is your servo arm parallel to the ground like mine is in the picture, or is it parallel to the long axis of the servo?
Mine is parallel to the ground and just for the heck of it I measured the length of the linkages and compared to the manual's specs. None of them were the same as the manual's specs with the swashplate level. I think the specs are basically just a ballpark guide. Since because of the ribs on the servo post you can't always get a perfectly horizontal arm position when installing it the linkages have to be adjusted to level the swashplate.
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Old Nov 30, 2012, 12:47 PM
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hi from second pic ,the elevator servo looks to be up a few degrees about the
same as swash .the circled servo is very close to level ,.level the elevator servo ,should get rid of a lot ,if not all of forward swash tip swash tip
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Old Nov 30, 2012, 01:30 PM
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Originally Posted by mdugas View Post
hi from second pic ,the elevator servo looks to be up a few degrees about the
same as swash .the circled servo is very close to level ,.level the elevator servo ,should get rid of a lot ,if not all of forward swash tip swash tip
By elevator servo, do you mean the rear one (to the right in the picture?). It is exactly how it came from the factory. The only change I made was to replace the circled one after the original one got stripped. Does that make any difference?
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Old Nov 30, 2012, 01:33 PM
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Quote:
Originally Posted by Hajile View Post
All trims and subtrims on the TX must be zero.
Yes they are. I'll re-adjust the servo arm and see what I get. This servo arm is different from the original, but I used the exact same distance to mount the servo rod.
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Old Nov 30, 2012, 03:28 PM
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The flybarless controller is in control of the servo. So to level the arms you need to either connect the servo direct to a receiver to find center, use a servo driver, or follow the instructions for the flybarless controller.
Since the servo's are mounted on an angle the arm needs to be perpendicular to the main shaft, at the servo's center of travel. If a little off due to the splines, that can be adjusted for on the flybarless controller.
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Old Nov 30, 2012, 03:35 PM
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After adjusting the link rod. Much better but not perfect. So is the swash level enough?
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Old Nov 30, 2012, 03:55 PM
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Try it

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Originally Posted by Lentar View Post
After adjusting the link rod. Much better but not perfect. So is the swash level enough?
Try to hover it and you'll know. I think you'll get a little forward movement in a hover, but there's only one way to find out. You have the training gear so you should be alright. Good luck.
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Old Nov 30, 2012, 06:48 PM
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Quote:
Originally Posted by Lentar View Post
After adjusting the link rod. Much better but not perfect. So is the swash level enough?
No its going to fly poorly, at best. The swash needs to be level at Zero pitch.
You really need to follow the instructions for you flybarless controller.
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