Plane turns into the opposite direction after curving with rudder

Hello,

I'm just tuning my pixhawk with arduplane 3.4 in my plane (old balsa plane, traditional layout, modified for brushless motor, 3 axis: Elevator, Rudder, Ailerons). It flies well on MANUAL mode, but in ALTHOLD there is a problem:

- when I use AILERONS for performing a curve it works perfect, plane automatically levels after I release the sticks and flies straight ahead

- when I use RUDDER for performing a curve, plane automatically levels (more or less) after I release the sticks BUT then it doesn't fly straight ahead; instead it flies a continous curve in the opposite direction which I originally steered. This is like a permanent afterward oversteering.

It isn't a mechanical problem of the rudder (for example tight hinges so it doesn't return to the neutral position) as it works perfect in MANUAL mode.

How can I change this behavior after rudder-operation?

First of all a correction to my first post: The regarding mode is STABILIZE, not ALTHOLD (I mixed it with the Copter-Modes). Sorry.

Concerning the RC4_REV:

If I move the rudder-stick to the right, then the YAW-bar in MissionPlanner moves to the right, and also the rudder moves to the right (for information: in MP there is the box "Reverse" right of the Yaw-bar checked).

But I did set the RC4-REV to -1 because of the following explanation in "Normal/Elevon/VTail Mode & Reversing Servos" on plane.arducopter.com:

"...

with no stick input (hands off the transmitter) roll the aircraft to the right. The rudder should turn towards the left as it tries to correct the roll.
Now roll the aircraft to the left. The rudder should turn to the right as it tries to correct the roll.

If the rudder moves in the wrong direction you should change the RC4_REV parameter. A value of 1 means no reversal. A value of -1 means to reverse the rudder.

..."

With RC4_REV = -1 the rudder moves in the correct direction when I roll the aircraft (corresponding to the text above).

But as you explained above, the RC4-REV should be +1 in my case.

How can I combine those two requirements?

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Andrew Tridgell December 8, 2015 at 10:46pm

rudder can be correct in manual mode but not correct in the RC4_REV parameter. That tells APM:Plane which direction to turn the rudder

If using right rudder gives you a higher PWM value on channel 4 then RC4_REV should be 1. If using right rudder gives you a lower value on channel 4 then RC4_REV should be -1
- Otmar Fugmann > Andrew Tridgell December 9, 2015 at 2:55am
  First of all a correction to my first post: The regarding mode is STABILIZE, not ALTHOLD (I mixed it with the Copter-Modes). Sorry.
  
  Concerning the RC4_REV:
  
  If I move the rudder-stick to the right, then the YAW-bar in MissionPlanner moves to the right, and also the rudder moves to the right (for information: in MP there is the box "Reverse" right of the Yaw-bar checked).
  
  But I did set the RC4-REV to -1 because of the following explanation in "Normal/Elevon/VTail Mode & Reversing Servos" on plane.arducopter.com:
  
  "...
  
  with no stick input (hands off the transmitter) roll the aircraft to the right. The rudder should turn towards the left as it tries to correct the roll.
  
  Now roll the aircraft to the left. The rudder should turn to the right as it tries to correct the roll.
  
  If the rudder moves in the wrong direction you should change the RC4_REV parameter. A value of 1 means no reversal. A value of -1 means to reverse the rudder.
  
  ..."
  
  With RC4_REV = -1 the rudder moves in the correct direction when I roll the aircraft (corresponding to the text above).
  
  But as you explained above, the RC4-REV should be +1 in my case.
  
  How can I combine those two requirements?

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Plane turns into the opposite direction after curving with rudder

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