Pictorial Pilot / Altrak question

Appreciate any ideas on why my autopilot(s) keeps trying to do aerobatics when all I really want is for them to hold a heading and altitude.

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You are absolutely positive the servo rotation direction is set up correctly? Reversed servos will definitely cause a diversion from straight and level.

I had a similar issue with a Pictoral Pilot. No matter what I did the autopilot would eventually put the aircraft into a steady left turn. After a bunch of troubleshooting including replacing the control head, they decided it was a bad servo. The new servo did in fact fix the problem. It does seem unlikely that you would have two bad servos, though.

Double check the servo wiring. There are two wires that you can reverse (see install manual) if the servo is running the wrong way.

Servos running in reverse would cause your problems.

Vern Little

Hi Ron,

If the AP is 'self inducing' it's own errors (i.e. it starts climbing and adds more up travel) or banks and adds more bank input, then the servo direction is reversed. If you used one of our harnesses you clip the yellow loop wire coming out of the connector to reverse the direction. If you rolled your own, then you have to probably change 2 wires to reverse the direction. You have a 50% chance of getting it right the 1st time, so this can be quite common. There is an easy test in the hangar. Turn on the AP (engage the servos), then go back and either lift or push the entire airplane tail up or down. The elevator should move in a direction to stop what you are doing to the plane (lift the tail of the plane up and the elevator should move up). For roll, simply engage the AP, then turn the heading knob and see if the AP is moving the ailerons in the right direction appropriate to the turn you induced.

If that is all working correctly on the ground and in the air, then it could be something else. In that case you better call one of the techies at TruTrak and see if you can trade a servo or controller (depending on their recommendation).

Hope that helps!

Cheers,
Stein.

I'll try it!

Thanks for all the input....I will give your suggestions a try and post my result.
Ron

Try this

To check for the proper elevator control while sitting on the ground try this.
Remove the static line from the Trutrak, turn on the altittude hold then put your finger over the hole where you took the static line and try to push your finger in the hole. This creates pressure in the instrument and simulates going down the elevator if connectted and wired properly will go up and when you slowly remove your finger, decreasing the pressure the elevator will go down.
Hope this helps you.

Norman