Van's Air Force
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Tail wag. Dynon autopilot
- Thread starter guido99
- Start date
Lenny Iszak
Well Known Member
Sam Buchanan
been here awhile
Dennis, congratulations on your new -9A!
You are experiencing the commonly known "Dutch Roll" (may not be the correct term but it's often referred to this way...) that most RVs exhibit in turbulence.
One thing you can do is make sure your feet stay on the rudder pedals even with the AP engaged. Your feet will dampen the yaw and prevent it from self-perpetuating.
This assumes the AP is set up properly and doesn't have any mechanical issues. Most APs have gain controls that you might try adjusting to alter the aggressiveness of heading corrections.
Enjoy your new plane!
Bubblehead
Well Known Member
First, make sure you have the latest software on both the EFIS and the Servos. Software is available on the Dynon site.
Second, get the latest installation manual for whatever Dynon EFIS you have. They can be found at the following location: http://www.dynonavionics.com/docs/support_documentation.html
They have instructions for setting up the autopilot. If the settings are not right the autopilot won't do a good job.
If that doesn't work, I suggest going to the Dynon support forum http://dynonavionics.com/cgi-bin/yabb2/YaBB.pl
Sam's advice is good too, but in my -8 in calm air I can have my feet on the floor without getting tail wag. I'm also wondering how a 2-axis autopilot can get the tail wagging. It can only roll and pitch and only roll could induce some tail movement, but for it to wag it would have to be trying to change heading or hunting for level, which sounds like a problem with the settings.
Second, get the latest installation manual for whatever Dynon EFIS you have. They can be found at the following location: http://www.dynonavionics.com/docs/support_documentation.html
They have instructions for setting up the autopilot. If the settings are not right the autopilot won't do a good job.
If that doesn't work, I suggest going to the Dynon support forum http://dynonavionics.com/cgi-bin/yabb2/YaBB.pl
Sam's advice is good too, but in my -8 in calm air I can have my feet on the floor without getting tail wag. I'm also wondering how a 2-axis autopilot can get the tail wagging. It can only roll and pitch and only roll could induce some tail movement, but for it to wag it would have to be trying to change heading or hunting for level, which sounds like a problem with the settings.
cfiidon
Well Known Member
Seen it
I have noticed this on rare occasions with my -8. I have the D-180 and AP74 installed.
It seems to be hunting heading. An aileron input causes a heading change from adverse yaw. The AP responds by releasing aileron input. It yaws the other way and the cycle repeats. I'm sure the rudder is moving in the slipstream when this occurs.
A slight pressure on a rudder pedal stops the cycle, and upon release it does not re-occur.
You can try this method to stop it and see if it works for you. Like I said, in my case it rarely occurs.
Don
I have noticed this on rare occasions with my -8. I have the D-180 and AP74 installed.
It seems to be hunting heading. An aileron input causes a heading change from adverse yaw. The AP responds by releasing aileron input. It yaws the other way and the cycle repeats. I'm sure the rudder is moving in the slipstream when this occurs.
A slight pressure on a rudder pedal stops the cycle, and upon release it does not re-occur.
You can try this method to stop it and see if it works for you. Like I said, in my case it rarely occurs.
Don
That is what dutch roll (what Sam was talking about) is. It is a coupling between the yaw and roll axis.
RV's exhibit this to a small degree in some situations (effected by C.G. position, etc.). If an autopilot is exciting / amplifying it, my guess would be that it is not set up properly. Use the suggestions made by others to confirm firmware and then run through the set-up process.
Sam Buchanan
been here awhile
Would we still call it "Dutch Roll" if the RV had been designed by someone other than Van???? 
