Thorp Air Command - T18.net

Just wondering if anyone has installed a yaw damper in their Thorp...

I have a rudder trim tab, and it is adjusted to nearly remove the need for any rudder input in cruise. The airplane has a two axis Garmin autopilot (coupled to a Garmin WAAS receiver) and it's really great. It has the ability to drive a yaw servo... just need to install a servo. My airplane is slightly nose heavy as it is and, although I hate to add weight, ever, the servo and associated hardware wouldn't weigh much, and will help with the CG.

My only experience a yaw damper (other than friend's turbine stuff) is in a BE-58. Once that damper was engaged, it was like the tail was locked in trail, with no perceptible yawing. It made for a very comfortable ride!

So, I'm considering it. Thoughts?

Thanks!

Peter

i personally would not go to the trouble of installing a yaw damper. Maybe if I ever had one I would think differently.....ignorance is bliss in my case.

Ryan,

That seems to be the consensus on the Van's forum. Most people don't see the need. But the people that do have the damper appear to love them, and are very happy.

Most of my flights are up high with the autopilot engaged. Although the Thorp handles turbulence well, I think the yaw damper would make for a superior ride.

But I'm on the fence...

I wouldn’t bother. Yaw trim is all you need. A dampener works better for a multi-engine.
Cubes

Wow this may be my new favorite case for RV guys just blowing $$$ ... unless you fly a V tail bonanza or a twin ... a yaw damper is not necessary. I will say I like Garry Green rudder "trim/lock' ... detailed in the newsletters and perhaps in the forum in 'somewhere'

_________________
Lee Walton
Houston, TX
N51863,N118LW
KEFD

I guess it's subjective...

I don't think the Thorp needs a yaw damper. But I'd guess, in turbulence, you might appreciate having one.

The vast majority of my time is in short-body Bonanzas. The tail wag never bothered me. Later, I was a partner in a Beechcraft 58- the "long" Baron. That plane flew great- far less yawing vs the Bonanza. But it was even better with the yaw damper engaged. It was astonishing, really, and surprised me.

I think the yawing is something we just accept as normal, and are completely used to it, and don't notice it.

Still on the fence... I do cringe at adding weight, so that's a factor. Then there's the $ and my labor.... ugh.

Just a follow-up on the yaw damper thought....

I went ahead and installed a Garmin GSA28 servo for the yaw damper. It took a couple of iterations to get it right. I finished the installation just before Osh this year.

On the first try I used a tiller arm, similar to what Van's recommends. But that setup seemed to not have enough torque for the application. So I switched to the Capstan setup. That one worked.

The yaw servo won't fully correct an off-centered ball due to am out of trim condition. (And Garmin spells this out as the correct, expected behavior.) But once in trim, the yaw damper will do a good job of keeping the ball centered. In my experience, if the ball is a bit off-center, engaging the yaw damper will bring it to center. I've found that, after takeoff, reaching 800 msl and pressing the A/P button (Garmin's minimum alt for engaging the A/P,) the ball remains centered, and you can put your feet on the floor. I don't notice a huge difference flying through turbulence; out of habit, my feet are guarding the pedals. But for most flights, it does a good job, and I can take it easy. I'm lazy.

Garmin's documentation allows for a couple of methods to deactivate the damper. One method calls for all servos to disengage when the autopilot disconnect switch is pressed. But optionally, you can wire it so pressing the A/P disconnect switch will deactivate the autopilot pitch and roll, yet keep the yaw damper active. This was the setup I wired. I need to change this... I've landed with the damper active more than once. You really notice it when you try to exit the runway- that servo will fight you with all it's got!

Would I do it again? Not sure. It works fine, and does reduce the need to work the rudder in most conditions. But those that suggested a damper is mostly needed in twins might be right. The BE-58 I used to fly didn't seem to have a yaw problem, but engaging that yaw damper had an amazing effect of locking the tail- you knew that damper was working! The difference in the T18 is less apparent.

I'll say this- the GFC500 A/P is amazing!

Peter