rv-10 rudder trim

[dmattmul]

I get that, though it also seems like it's the case that the Garmin/Dynon YD functionality will also try to coordinate, and that the flight control forces are so small on these light airplanes that it's OK for the two to be comingled (of course, in software, it is of course two different computations adding to the yaw servo command). <--- This is basically what I've gleaned from reading about RV10 rudder trim/YD, though I've not seen it really confirmed from Garmin, at least other than people mentioning the airplane stays coordinated with YD turned on.

I know Garmin has a note that their YD isn't designed to trim, but I'm wondering if that's really a disclaimer for if the airplane requires "too much" control input to stay coordinated in steady state. They want people to be aware that the servo's authority to coordinate in steady state (ie, trim) is minimal/"non existent" even through it will actually try. And thus, if an airplane with sufficiently light control forces is already mostly trimmed, the YD servo is actually sufficient in lieu of a dedicated spring/tab based trim system.

Use your feet for the big (actually fairly light inputs) and the YD for the inputs that are too fast for one's feet. YD seems to react like most Garmin electronics much faster than human input, thank you!! My wife to this day would probably be staying on the ground without this. 6 years of having YD and wouldn't take off without it, priceless.

 

[rocketman1988]

I get that, though it also seems like it's the case that the Garmin/Dynon YD functionality will also try to coordinate, and that the flight control forces are so small on these light airplanes that it's OK for the two to be comingled (In software, it is of course two different computations adding to the yaw servo command). <--- This is basically what I've gleaned from reading about RV10 rudder trim/YD, though I've not seen it really confirmed from Garmin, at least other than people mentioning the airplane stays coordinated with YD turned on.

I know Garmin has a note that their YD isn't designed to trim, but I'm wondering if that's really a disclaimer for if the airplane requires "too much" control input to stay coordinated in steady state. They want people to be aware that the servo's authority to coordinate in steady state (ie, trim) is minimal/"non existent" even through it will actually try. And thus, if an airplane with sufficiently light control forces is already mostly trimmed, the YD servo is actually sufficient in lieu of a dedicated spring/tab based trim system.

The yaw damper responds to transients, not steady state inputs. The best solution, IMO, is a fixed wedge and a yaw damper.

Once you figure out the steady state offset, the yaw damper does a wonderful job of keeping it to that center point.

As I have stated before, I have an electrically driven, spring bias rudder trim. Since I found the steady state center, I really haven’t moved the rudder trim at all. It was a bunch of extra effort and complexity for little to no reward. That’s why I think a fixed wedge would do the same thing for the steady state trim.

The yaw damper is wonderful, and it is used regardless of hand flying or auto pilot.

 

[chris1seto]

The yaw damper responds to transients, not steady state inputs. The best solution, IMO, is a fixed wedge and a yaw damper.

Once you figure out the steady state offset, the yaw damper does a wonderful job of keeping it to that center point.

As I have stated before, I have an electrically driven, spring bias rudder trim. Since I found the steady state center, I really haven’t moved the rudder trim at all. It was a bunch of extra effort and complexity for little to no reward. That’s why I think a fixed wedge would do the same thing for the steady state trim.

The yaw damper is wonderful, and it is used regardless of hand flying or auto pilot.

> Once you figure out the steady state offset, the yaw damper does a wonderful job of keeping it to that center point.

Aren't you saying there, though, that the servo is capable of some very limited amount of trim authority? This is what I was alluding to in my post. I think it may be the case that the servo will actually trim, but only with very limited authority. So a wedge to get it close + YD to take out the final offset is functionally the same as having a dedicated trim system.

This is the real tell all question (I think): If you are flying along in an RV10 with YD, and the ball is slightly out (let's say: 1/4th out of coordination), if you enable YD, will the ball move to center as the yaw servo commands a limited amount of trim? Remember, straight and level, so no yaw transients (assuming this is airplane is basically stable in yaw).

 

[dmattmul]

> Once you figure out the steady state offset, the yaw damper does a wonderful job of keeping it to that center point.

Aren't you saying there, though, that the servo is capable of some very limited amount of trim authority? This is what I was alluding to in my post. I think it may be the case that the servo will actually trim, but only with very limited authority. So a wedge to get it close + YD to take out the final offset is functionally the same as having a dedicated trim system.

This is the real tell all question (I think): If you are flying along in an RV10 with YD, and the ball is slightly out (let's say: 1/4th out of coordination), if you enable YD, will the ball move to center as the yaw servo commands a limited amount of trim? Remember, straight and level, so no yaw transients (assuming this is airplane is basically stable in yaw).

For my 14 I found that the YD can remove about 1/2 ball of coordination and that works well for all phases of flight except departure where I need to add a slight amount of rudder. This probably depends on many factors including airframe set-up and limits one sets for the yaw damper itself. I don't have a wedge and in level flight and YD off my ball was very close to being centered so never bothered with it. Turning the YD on easily corrects this. The 10 to date seems to behave about the same but limited number of hours to date.

 

[chris1seto]

For my 14 I found that the YD can remove about 1/2 ball of coordination and that works well for all phases of flight except departure where I need to add a slight amount of rudder. This probably depends on many factors including airframe set-up and limits one sets for the yaw damper itself. I don't have a wedge and in level flight and YD off my ball was very close to being centered so never bothered with it. Turning the YD on easily corrects this. The 10 to date seems to behave about the same but limited number of hours to date.

This is great information, thanks. Just to confirm: is this data point for Garmin or Dynom?

I'm thinking I'll do YD + wedge in my build.

 

[dmattmul]

This is great information, thanks. Just to confirm: is this data point for Garmin or Dynom?

I'm thinking I'll do YD + wedge in my build.

Garmin. I have not heard much about the Dynom YD.

 

[ewumnrr]

Elvin has had a project with Garmin to figure out how to get the Yaw Damper servo to do proper rudder trim / ball centering throughout the flight. He got it fully working and it had to do with proper calibration. It seems to be important to calibrate the G3X/ADAHRS and the G5 at the same time while the plane is properly level on ground. He jacked his plane up just to rule out any errors but potentially that isn't necessary. After the calibration, the ball was always centered, even at 165 knots, so all myths concerning the servo running out of torque were debunked.
This explains why across the board of different airplane types, there was always someone that said, it is working for him, but for most, it doesn't out of the box. If you calibrated the G3X on one day and the G5 on another, it might foil proper operation.

 

[BobTurner]

After the calibration, the ball was always centered, even at 165 knots, so all myths concerning the servo running out of torque were debunked.

I thought the question was, How far out of trim (yaw) can my RV be, and have the yaw dampener correct it? Logically, if an airframe is bad enough, the yaw dampener won’t be able to make it fly straight. So, how does the test plane fly, dampener off and feet on the floor? Does it start with 1/2 ball out of center, or 2 balls out of center? How bad before it can’t 100% correct, and a fixed wedge will be needed to ‘help’?

 

[Richard Connell]

Elvin has had a project with Garmin to figure out how to get the Yaw Damper servo to do proper rudder trim / ball centering throughout the flight. He got it fully working and it had to do with proper calibration. It seems to be important to calibrate the G3X/ADAHRS and the G5 at the same time while the plane is properly level on ground. He jacked his plane up just to rule out any errors but potentially that isn't necessary. After the calibration, the ball was always centered, even at 165 knots, so all myths concerning the servo running out of torque were debunked.
This explains why across the board of different airplane types, there was always someone that said, it is working for him, but for most, it doesn't out of the box. If you calibrated the G3X on one day and the G5 on another, it might foil proper operation.

I think there’s some confusion here.
The additional ADAHRS is in the GFC507 not the G5 (obv there is on in the G5 too)
Many people are indeed ignorant of the need to calibrate the GSU25, the G5 and the GFC500
I have yaw trim. The AP will happily center the ball with the trim servo depowered in cruise. I haven’t tested other scenarios though.

 

[ewumnrr]

I think there’s some confusion here.
The additional ADAHRS is in the GFC500 not the G5 (obv there is on in the G5 too)
Many people are indeed ignorant of the need to calibrate the GSU25, the G5 and the GFC500
I have yaw trim. The AP will happily center the ball with the trim servo depowered in cruise. I haven’t tested other scenarios though.

Thanks for adding this information, I agree, three units need to be calibrated at once (manual says before the aircraft moves) and the plane needs to be brought to a level attitude on ground while doing this.
There is another attitude sensor in my GNX375 GPS unit, I guess that one needs to be recalibrated in same session as well.

 

[GaryK]

This is great information, thanks. Just to confirm: is this data point for Garmin or Dynom?

I'm thinking I'll do YD + wedge in my build.

Dynon and Garmin, they work the same. My 10 has Dynon HDX's and the YD. I never added a wedge because the ball is so close to being in the center without it.

Gary

 

[Richard Connell]

There is another attitude sensor in my GNX375 GPS unit, I guess that one needs to be recalibrated in same session as well.

I don’t believe any of the 2” navigator series AHRS are used for miscompare - and they aren’t on the canbus. I think they’re just there for Bluetoothing to devices.
But yes should do them all at the same time regardless.