Can you tell me more about it, please?Pixhawk pairs with a pi. There are others based on single board computers. Very powerful. Easy to port to your needs. Cheap starting point. There is a ton of open source stuff that can be combined up to make as much automation and screen bling as you want. I am on a project that is well down this road.
My pitch autopilot work with a pint glass jar, 2 thermistors in parallel on a small PC board in an small cavity with 1/8 brass tube on each end mounded to the jar lid. One end of the brass tube to the outside air and the other to the inside of the glass jar. Go up , air come out of a tube on the jar lid and cools the first thermistor more that the second that is downstream. Go down and the reverse. Balance analog circuit that get un-balanced. Drives a LM-556 to make the square pulse train for the servo. If I remember correctly it would hold a pressure altitude to within about 20' when adjusting the gain before going into oscillation. Used a 10K pot for up or down trim. Autopilot also had LED indicators when the servos were moving up or down.Doable for not a lot of money (just a fairly large amount of work), and small model servos can run servo tabs on the ailerons instead of driving the ailerons directly. But if all you want is a wing leveler, you should just watch ebay and the various experimental a/c type forums for a used NavAid. You can probably pick one up for under $200, if you're not in a hurry, and it will follow an analog CDI, or with the optional 'smart coupler', it will follow a GPS course. I flew one in my RV4 for many years; works fine.
And for your tidbit of the day.... Both a unique homebuilt on my airport called a Messersnipe and a Thorp T-18 I used to own, had wing levelers based on...air. They used a small jet of air, blowing between two thermistors (mounted in a coffee can). When the plane turned, inertia of the air stream meant it cooled one thermistor more than the other, and an analog circuit comparing their resistance would output a varying voltage driving a model airplane servo, which drove a trim tab on an aileron.
BTW, the Messersnipe is a really sweet flying plane; that EAA forum thread might be a fun read for some of us that like older a/c.
HORRIFIC CHOICE You missed the 20% duty cycle.These servos are geared and the current and all the specs are listed. No problem with over riding if you use the servo to operate trim tabs where you can make large enough to control the airplane but easy to override. I make the tabs a little large at first and then adjust the area and travel to suit. No clutches or springs.
What I use on for the elevator trim on the SSSC and the JMR.
Have been using these servos since about 2010.
Stalled current-- 650 mA @ 12 volts
Max force-- 44.9 lbs ( 200n )
Actuonix L16-S Mini Linear Actuator with end Limit Switches. The L16 is a step up from our L12 line. It features a larger, more powerful motor and is capable of faster speeds.www.actuonix.com
Been using these servors without any problems since 2010. If I was to say 0, you would say 1. That duty cycle would be for the max force. Very little power required to operate a trim tab controlled by the autopilot.HORRIFIC CHOICE You missed the 20% duty cycle.
OP wants an autopilot, not electric trim. Trim tabs are not designed for continuous movement. They also are not designed for full control. You will have a hard time keeping straight and level when your control inputs are 10 seconds late.
Almost home made leveraging the same conceptBeen using these servors without any problems since 2010. If I was to say 0, you would say 1. That duty cycle would be for the max force. Very little power required to operate a trim tab controlled by the autopilot.
I planned to coupling my auto pilot to a GPS and VOR but never did. I just looked at the GPS heading and set the manual trim on the autopilot to hold it on that heading.