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RV-9 Rudder Yaw

PerfTech

PerfTech

Well Known Member
Has anyone else that has time in an 8 or 7 noticed an excessive amount yaw around the rudder axes in a 9 as compared to the others? It really seems to show up in rough air and wants to oscillate back and forth several times as it subsides. Rudder control input doesn't seem to help. Perhaps this is normal in the 9 with it's longer wings, as once moving they will have considerably more momentum and leverage on the fuselage. I am interested in other peoples experiences
with this problem. This is my only complaint with the flying characteristics of my RV-9A. Regards all, Allan:rolleyes:
 
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Oscillatory yaw mode

This oscillatory yaw mode is called "dutch roll mode" and all RV's exhibit this to some degree. I haven't flown a -9 but the -8 does it pretty strongly.

The most important thing to reduce this is to keep the rudder still by putting both feet firmly on the pedals. If you are light on the pedals or off them completely, the rudder is free to swing and does not contribute to damping the yaw.
 
scsmith said:
This oscillatory yaw mode is called "dutch roll mode" and all RV's exhibit this to some degree. I haven't flown a -9 but the -8 does it pretty strongly.

The most important thing to reduce this is to keep the rudder still by putting both feet firmly on the pedals. If you are light on the pedals or off them completely, the rudder is free to swing and does not contribute to damping the yaw.
Click to expand...

It seems to make no difference feet on solid or off. The 9 seems to do it far more than the 7 or 8 we fly daily. this exadurated yaw I speak of seems only comon to my 9.
 
I thought only "short tailed" sixes........such as mine, did this (the dutch roll). So add RV6's to the list.

L.Adamson --- RV6A
 
Yep...

The 9 does wag it's tail in rough air, if that is what you are referring to. I keep my feet on the pedals. Using the AP in rough air seems to reduce it some, but I am not exactly sure why.....Guess the trutrack is faster on the draw than me.

Regards,
Chris
 
carguy614 said:
The 9 does wag it's tail in rough air, if that is what you are referring to. I keep my feet on the pedals. Using the AP in rough air seems to reduce it some, but I am not exactly sure why.....Guess the trutrack is faster on the draw than me.

Regards,
Chris
Click to expand...

Keep an eye on this thread as we are working on a fix for this problem. We will be posting results hare in the next few weeks. Regards, Allan
 
Should I stop building my rudder until you post? (Just about to seal it up...)

PerfTech said:
Keep an eye on this thread as we are working on a fix for this problem. We will be posting results hare in the next few weeks. Regards, Allan
Click to expand...
 
RUDDER YAW!!!!

mculver said:
Should I stop building my rudder until you post? (Just about to seal it up...)
Click to expand...

Actually you may want to work on another part for a short time. I ordered some of the parts tonight and picked up a spare rudder assembly Sunday for this project. Most of the drawings and calks are complete and it won?t be long. This unit we are building will be an electronic yaw dampener, automatic turn coordinator and will also double as electric rudder trim. If you can hold off for a short time it will I am sure be worth your while. Regards, Allan:rolleyes:
 
Progress on Yaw Dampner!!!!!

I have been somewhat under the weather as of late but am now on the mend and ready to get back on this project. I purchased another rudder for the project and now have all electronic components in hand. I will start this coming week and will post progress asap. You guys that expressed interest in this item, Thank you for the patients and hope to have something very soon. Regards, Allan
 
PerfTech said:
It seems to make no difference feet on solid or off. The 9 seems to do it far more than the 7 or 8 we fly daily. this exadurated yaw I speak of seems only comon to my 9.
Click to expand...


I have noticed that my 9 moves around quite a bit more in rough air than the 4,6 and 7's I flown. I have found that I need to turn my AP off and put quite a bit of pressure on one rudder peddle to stabilize it. As far as being an issue, I don't think it is. It's only in rough turbulence.

Now remember that when I fly in turbulence it's in Tehachapi, one of the rougher places around.
 
N916K said:
I have noticed that my 9 moves around quite a bit more in rough air than the 4,6 and 7's I flown.
Click to expand...

My experience, is that it's much the same as my 6A. Of course, some have assumed that the 9 would be a smoother plane in rough air.

L.Adamson ---- RV6A
 
The RV-8 in my avatar exhibits a rather pronounced dutch roll in rough air, especially bad in the strong thermal turbulence of 100+ degree Texas summer days with gusty winds down low.

If I don't use the rudder pedals to cancel them out and keep them out, the oscillations can get increasingly worse and worse in amplitude until they start to become quite scary.

I've read that squeezing the trailing edge of the -8's rudder skin down a little narrower (like what you can do on the aileron skin on the "light wing" side to help fix a "heavy wing" on the other side) can help reduce the dutch roll tendency. Of course you can't to that to a -9's (or a -7's or -10's) rudder due to the different way the trailing edge is designed.
 
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