Thinking about a Third Autopilot Servo

[Bdflies]

Jared,
Have you fitted the yaw servo? Or, still investigating?
My last couple of flights have included some autopilot time. Granted, I have the gain turned down pretty much, but it seems to do pretty good. In really turbulent conditions, I'm sure it wouldn't be acceptable, but pretty good so far. Yes, the Patrol does exhibit adverse yaw, but not too bad.
I was wondering of your autopilot had the option of lowering the 'gain'. Gain, in Garmin's vernacular, is the speed or aggressiveness that the servos employ. Others may use a different term.
Just a thought...

Bill

[jaredyates]

Still investigating. We had planned to go to Sun-n-Fun and get more experience with the two axes, but cancelled the trip due to high winds at the end of last week. Dynon has released the first version of the software to support the third servo, but I still need to get more straight-line flying without it to decide if it is worth the trouble and weight.
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[mswain]

I am at the point of rigging my rudder pedals. I like the idea of the closed loop coming off the back side of the rudder pedal arms. For now it would loop around another pulley, but eventually the pulley will be replaced with a rudder servo down the line. I like the idea of having it up front and not back in the tail.

I don't have enough room between the cable arm and firewall. Any issue with creating a cutout on the firewall to accommodate the pulley? I would build some sort of cover that would protrude into the engine compartment.

[whee]

I've tried to make provisions to installed a system similar to Steve's Aircraft Pacer rudder trim with will allow me to install just rudder trim or an autopilot servo. I don't plan to install it until I need it but here is their sketch. I think it would work well for a BH.

[svyolo]

There are a couple of options for reducing adverse yaw. One you can have offset bell cranks/control horns that give you some differential ailerons when you move the stick. More down on one side, than up on the other. RC planes, which i haven't flown since 1980, have had electronic "mixing" as a feature in the transmitters. You can add in rudder when you command aileron. It might be doable several ways on a homebuilt. When the autopilot commands roll, have 2 servos connected to the roll function. One for the ailerons, one for the rudder. You could easily have an adjustable length servo control arm on the rudder servo to get the "mix" close.

[svyolo]

I have been a "feet on the floor" pilot for so long, I wonder how long it will take me to remember how to fly again. I have only used rudder pedals for NWS and crosswind takeoffs and landings for a long time.

[Mark Goldberg]

SVYOLO - you will have to remind your feet how to dance. One thing that minimizes adverse yaw is rigging your ailerons both a little "up" when you do the final rigging of your plane and its controls. Not a lot. Maybe 1/4" to 1/2". This minimizes adverse yaw a little. Mark

[svyolo]

Mark;
Yeah that does sound like it would work. It might also increase cruise speed a little, but cost you a little on the stall speed.

Do any of the EFIS enable autopilot functions have a "mixing" function for the rudder/aileron? Or a Yaw Damper function?

[svyolo]

Sorry, I should have Googled before I asked a question. There are yaw dampers for experimental autopilots. Trutracks is 725 dollars, and weighs 3.25 pounds, including the servo.

[Bdflies]

Garmin G3X touch also drives a 3rd axis servo. You just have to hook it up and configure it. SV, I'm going to suggest that you may be missing the forest, because you're focusing on the trees. I'm flying a Patrol and have a little time in a 4 place. I'd never say that these planes display no adverse yaw, but it's not objectionable at all. I have pitch and roll servos(no yaw damper) in my Patrol and am quite satisfied with the system performance. Adverse yaw is present, but isn't bad.
If you've been flying trikes -exclusively- for a long time, it's the takeoff and landing that are going to demand your attention! There's no autopilot servo on earth that'll keep you straight, when you push full throttle in a high horsepower taildragger. Find a Decathalon and make friends with it! As Mark said; it'll remind your feet how to dance.

Bill

[svyolo]

Bill;
I left the forest, and the trees, 35+ years ago. I don't recognize either. LOL. And I didn't know either very well then. (80+ GA hours). I spent the last 30 years flying in front of a very different engine(s). I will try to remember to google my question, before I post it here. Right after I asked a question about a yaw damper, I realized that it would be so easy to implement with modern solid state inertial reference instruments, it HAD to exist. And does.

I got my private in 1980. Was flat broke and didn't fly again until the tax payers payed for it. Flew in the USMC from 1989-1996. Airlines since then. Feet on the floor, autopilot on whenever possible. I know a lot, but it is not that applicable to building a homebuilt. I do know some stuff that most here do not. But I suspect I have a lot more to learn from those here, than I have to offer.

I will try to lurk more, and post less.
John

[Bdflies]

"Lurk more and post less"?? Please don't! Anything you ask is assured to stir up a conversation. At some point, useful information will percolate to the surface. Ya just have to figure out when that point is. If you don't ask, we'll all miss out!
Your "feet on the floor" comment suggest d to me that you were burning kerosene, in copious amounts. No doubt, you've forgotten more about aviation than some of us have learned. My first white knuckle grip on a yoke, was in '74, but my limited experience is behind piston slapping antiquated flat engines, like the one in my Patrol...that immediately lurches left when the throttle is pushed forward...
And I thank you for your service to our Great Nation.

Bill

[whee]

I agree with Bill!

[svyolo]

I was dumbfounded when I saw that an experimental yaw damper costs 700 dollars, and weights just over 3 pounds. Then quickly realized that with modern solid state inertial references, that is probably overpriced.

[jaredyates]

In the case of the Dynon system, the $750 is just for the servo. The "brains" of it are in the Skyview box, where the brains of the rest of the autopilot are. I'm starting to think that there aren't much brains to it though, I haven't been able to get it to work right. They still haven't released any documentation about how it is supposed to work, and it isn't as intuitive as I had hoped.