Tail wobble and Rudder Servo question

[keithstric]

Hello all!

I'm a newb and need some help. I've assembled and setup a Venture 30 with the Webra 35 engine and G500T gyro. All seems to be well except that the tail wobbles quite a bit. In my radio (JR 6102) I have the following configured for the [Travel Adj] section:

Rudd
L 75%
R 75%

Gear
+ 45%
- 35%

What else can I do to minimize the wobble, sometimes it gets quite bad?

Also, if looking at the rudder servo, when the arm moves all the way to the right, the bottom side of the control arm hits the center of the servo, should this happen? If not, how can I fix it?


Thanks in advance,
Keith

[tommyboy196]

Hi Kieth
Did you try turning down the gyro gain?
That should help the wobble.

Tom

[keithstric]

I think that's what someone at the field did. Thanks!

Keith

[WayneBrown]

Put a longer arm/wheel on the servo.
with a value of 45% for the gain, and you still have a wobble, the mechanical advantage of a longer arm should cure the issue.
Also remove the link at the servo end, and make sure there is absolutely no binding in the linkages..

[keithstric]

LameBird,

I'm not sure I understand what you mean. If I move the rudder control arm farther up the servo arm it will start to bend the rudder control arm. I've included some picutures that hopefully shows this better.

Keith

[WayneBrown]

The pictures say a lot here, The ball should be moved to the outside of the arm, instead of the inside as you have it installed, to prevent the binding shown.
If you are still having a wag issue, I'd reccomend moving the ball out from center to the end of the arm, and adjusting the limit to prevent binding caused by too much travel.
Moving the ball location futher out changes the moment of the lever (arm in this case) increasing travel, and speed.
Adjusting the rudder ATV will only change the speed the machine turns, not limit the travel of the servo which is different than the other channels on the radio. To adjust the servo travel in this instance, you need to set the limits on the gyro itself.

[keithstric]

WayneBrown,

Thank you for all your help. Today is the first time I've had time to mess with this and try and work it out. I moved the ball on the other side of the arm and it doesn't bind as much. It still travels too far and causes binding. However, it did seem to fix the tail wobble.

I tried adjusting the limit on the gyro but then the servo didn't move far enough to the left. Is there a way to adjust the travel on the servo just when it's moving to the right? Or, can I adjust the travel in my Tx (Rudder or Gear)?

Thanks again,
Keith

[WayneBrown]

there are two ways to look at this, Firstly, if you have an uneven bias there is something incorrect in the setup. Adjust the length of the control rod to allow an even amount of throw right or left. This is the preffered method to keep everything linear.
Second, get the most throw possible, and fly it. The gyro will not allow for full travel during flight.
At center, the bellcrank should line up at 90* to the tailbox housing, and the tail blades should have a little pitch in them.

[Ivan]

If you want to use the longest possible hole in the arm, you may consider flipping the tail servo over so teh output shaft is lower, and make the arm point up, this should keep your tail rod fairly close to the proper position.

[keithstric]

Thanks everyone for your help. I finally got this right I think. Here's what I did.

I removed the servo arm, I then lowered the limit on the gyro so that the servo didn't travel too far either way. Then I used the tx to move the rudder all the say to the right, I then attached the servo arm back and ensured that I had full travel to the right. Moved the rudder all the way to the left using the tx and it has full travel all the way to the left. There is now no binding at all in either direction. Also, the servo arm is centered properly.

It took some doing and a couple of kinda scary flights but the tail wobble is now gone and it does great.

Thanks again for all your help.

Keith