Lancair servo slip

[iflyaz]

I have a newly built Lancair 360 with Skyview autopilot. I am getting Pitch Slip occasionally, even in only mild turbulence. SV-32 servo, 100% torque setting.
I originally had the stock bobweight on the elevator idler arm. I removed the bobweight and tried it again, it is better but still slips once in a while.
Do I need a SV42 servo?

 

[Dynon]

Maybe. However, there are some improvements coming to our next major release that will improve both trim sensing and slip indications for some customers. We have a "public beta" of just that feature that you can read about here: http://dynonavionics.com/cgi-bin/yabb2/YaBB.pl?num=1402684755/11#11.

It's most likely to make a difference for you if you're also getting more pitch up/down trim annunciations than you deserve while on AP. If you're not comfortable running the test, our next "official" software release should hit around Oshkosh. And a bigger servo is likely to help too. We're happy to swap you if you want to go that route instead.

 

[vlittle]

Here's what I've found on high performance aircraft:

Even though my elevator and aileron forces are light on my Harmon Rocket, the wide speed range of the aircraft can require a lot of pitch trim changes until the aircraft stabilizes in speed.

If the autopilot is engaged too soon, the autopilot may ask for more trim adjustments and can settle into a configuration where the trim is fighting the autopilot servo.  This extra load on the servo can then lead to slip in turbulence.

I was going to upgrade from an sv32  to an sv42 until I thought about the problem... It was a trim issue, not a servo power issue.

The solution I came up with is a trim controller that provides autotrim for the SkyView .  It's an open- source design, but available as a finished product as well from MakerPlane as the M-PWR-2AT. Here's the project link:

http://54.166.95.70/redmine/projects/m-pwr-2

I've been flying this in my HR for some time and not only does it eliminate slipping, it lowers workload and keeps the aircraft in perfect trim. The trim controller provides fail-safe operation and speed scheduling as well. 

Vern