Yaw, trim tab and auto pilot.

Tbarsic · #1 02-26-2020, 07:29 AM

Hello, everyone long time lurker new to posting.
I just picked up a nearly finished RV 10 empennage kit from a fellow Vans owner. I am checking over the work and diving into the instructions. So far the work is excellent.

I am trying to plan out what mods I was going to accomplish for the empennage. When it comes to rudder trim, yaw dampener and autopilot I am slightly confused. Can all three be utilized? Is the rudder trim really required with an autopilot? I am thinking of just autopilot servos and yaw servo. Do I need to decide on avionics now before I get the autopilot servo and yaw dampener?

I am convinced I will do with an autopilot and yaw dampener but not sure about the trim tab.

Thanks

BrianDC · #2 02-26-2020, 07:55 AM

Yaw Damper would be part of your autopilot if you decide to go that way. Plenty of opinions if it is truly necessary or not. This is NOT a replacement for a trim tab (fixed) or a rudder trim system even if some people use it that way sometimes.

Honestly, no absolute need to make decisions on what you want to do at this point in the build. Easy enough (with a little effort) to install a Yaw damper or trim later in the build. Decisions on Dynon or Garmin may impact what you install or if new avionics are released in the future. For rudder trim, there are some examples of electronic trim tabs, bolt-on manual systems (Aerosport), or just a wedge installed on the rudder. All work and are being flow.

bkervaski · #3 02-26-2020, 08:21 AM

The yaw damper definitely helps in turbulence .. calms things right down .. quite nice!

I would definitely install all the bracket kits, and then choose later what servos to install.

If you're having a wiring harness built by SteinAir ask them to pre-wire for everything, it won't add much to the cost.

It's a lot easier to do it now than later .. I installed my yaw servo at 150 hours and while certainly doable, If I had a time machine I wouldn't hesitate going back and install the brackets when I had the chance, butterflies be damned

Tbarsic · #4 02-26-2020, 09:16 AM

I appreciate the feedback. I am thinking now that the autopilot will do yaw damper duties, correct?

Is it better or easier for the autopilot to have trimmed aircraft? If that is the case then I will need to install trim tab and servo for yaw then the servo for autopilot and no servo for yaw damping.

bkervaski · #5 02-26-2020, 09:24 AM

Yaw Damper != Trim

Quote:

I am thinking now that the autopilot will do yaw damper duties, correct?

Yep, controlled by the autopilot, the yaw damper does just what it says .. takes the bite out of sudden yaw movements .. the overall effect is a calmer airplane when you're getting kicked around by turbulence .. while it does help trim on long flights with wind pushing you around, it won't do a great job of trimming an out of trim airplane.

Quote:

Is it better or easier for the autopilot to have trimmed aircraft?

Yep.

I think it's safe to say that it's completely normal to have to adjust with some kind of rudder trim, but you won't know until you're well into your phase 1.

BrianDC · #6 02-26-2020, 09:28 AM

Quote:

Originally Posted by Tbarsic

I appreciate the feedback. I am thinking now that the autopilot will do yaw damper duties, correct?

Is it better or easier for the autopilot to have trimmed aircraft? If that is the case then I will need to install trim tab and servo for yaw then the servo for autopilot and no servo for yaw damping.

Ok, I think something is getting lost here.
Autopilot can control 1, 2, or 3 axis. Pitch, Roll, and Yaw. Most typically do 2-axis, but if you want to you can also install the Yaw control (Also called a Yaw Damper).

This is all distinct from trim control. While an autopilot can correct for an out of trim condition, it's not the best practice. Yes, you will want to install a rudder (or Yaw) trim.

Auburntsts · #7 02-26-2020, 09:58 AM

My thoughts are well known on this subject -- rudder trim-yes (number of ways to the skin the cat both fixed and adjustable--I use the Aerosport spring bias system), yaw damper - no.

Plummit · #8 02-26-2020, 10:01 AM

Quote:

Originally Posted by Tbarsic

I appreciate the feedback. I am thinking now that the autopilot will do yaw damper duties, correct?

Is it better or easier for the autopilot to have trimmed aircraft? If that is the case then I will need to install trim tab and servo for yaw then the servo for autopilot and no servo for yaw damping.

The next question will be: "Which auto pilot?" For years Tru Trak had the duties with the G900X, but if you go Garmin with the G3X you will get to use the Garmin autopilot, which in my humble opinion is Way better!

-Marc

Tbarsic · #9 02-26-2020, 11:24 AM

Quote:

Originally Posted by Auburntsts

My thoughts are well known on this subject -- rudder trim-yes (I use the Aerosport spring bias system), yaw damper - no.

Auburntsts, how well does the Aerosport spring system integrate with an autopilot? I want to avoid excessive work for the autopilot servo. I don't want the two systems to fight each other.

Auburntsts · #10 02-26-2020, 12:18 PM

Quote:

Originally Posted by Tbarsic

Auburntsts, how well does the Aerosport spring system integrate with an autopilot? I want to avoid excessive work for the autopilot servo. I don't want the two systems to fight each other.

It doesn't integrate as far as I know being a simple mechanical system. I only have a 2-axis autopilot so it's a non-issue for me. I'm blissfully ignorant as to how to integrate it into a 3-axis system.