Dynon to control pitch, Trio to control roll

[melkel2000]

First of all, I’m flying an RV-9A, VFR only airplane. My autopilot installation is there simply to make long cross countries more pleasurable. I don’t need my AP system to fly a precise IFR approach.

I am adding a Dynon pitch servo, controlled by a D180, to my airplane which already has a Trio EZ Pilot installed for roll. I originally wanted the Dynon servo to see 12V power on the red wire only when the Trio control head was powered on. However, the only switched 12V output from the Trio occurs when the Trio roll servo is engaged and seeing power. I would like to tap into this 12V supply and run that to an external relay that I’ve added to behind the panel. This power will close the relay which in turn would supply 12V power to the Dynon pitch servo. So, the Dynon pitch servo will never see 12V power unless the Trio servo is seeing power.

Presently, my AP disconnect button is only attached to the Trio head unit. Pressing this button, which brings a wire to ground, interrupts power to the Trio servo. Since the Dynon servo will be tapped into this line, this will also open the external relay that I’ve added, which in turn, interrupts power to the Dynon servo.

My questions are:

-I will be able to use the Trio for roll and elect to not engage the pitch servo. However, I will not be able to engage the pitch servo unless the roll servo is engaged. Is this going to be a problem? I can’t imagine wanting to engage only the pitch servo.

-I realize that since the yellow Dynon servo wire (AP disconnect) will not be connected, I won’t be able to take advantage of using the Control Wheel Steering for the pitch servo. I don’t have a problem with that. However, when the 12V power to the Dynon servo is suddenly interrupted as I explained above, what indication will the D180 have? Will it show an error message or will it just show that the pitch servo has been disconnected?

 

[dynonsupport]

This really isn't an acceptable way to operate the Dynon servo. It's designed to have power all the time. Momentary power interruptions may or may not cause a disconnect depending on how long they are. If they do cause a disconnect, they will cause a critical error on the Dynon since the servo disappeared. We really never designed the servo to be powered on and off in flight.

Why do you want the Dynon servo to only be usable when the Trio is engaged? Maybe if we understand what you are tying to achieve we can help you out a bit more.

 

[melkel2000]

My thinking behind this was to have the ability to completly remove power from the entire AP system if needed. I can do that with the Trio by simply turning it off. If I tapped into the Trio power, then I would be able to remove power from both APs with a single switch.

I could easily put in a stand alone Dynon servo power switch as is shown in the 101046-005 Ref F Servo Mounting Instructions. Then, if I need to remove power from the servo in an emergency, I just flip the switch off. In this case then I would tap in to the existing AP interrupt switch and pressing it would disengage both the Trio and Dynon.

Does this sound like the better way to go?