Autopilot/EDC10A Installation - Heading Problem

[longezdave]

I've flown with just the D10A for a year or so and just installed the EDC10A and roll servo and 5.3 firmware. I played with the sensitivity for the roll servo a bit and thought maybe 5 was going to work. I put in a couple of headings and it tracked well. I tried a 180 and it did OK - not too smooth, but it did turn around.

Then I tried another heading. It was starting out very slowly rolling to the right. I noticed that the heading indication started decreasing as if I was turning left. The bank kept getting steeper and the heading scrolled faster to the left....... I had to disconnect. It did that four times in a row and I decided to pack it in for the day. What would make it do kinda OK for a while and then start this behaviour?

After this, I noticed that the bank indication on the EFIS was not leveling right away after a bank and then rolling back to level.

I should mention that I have not yet connected the pitot and static pressures to the EFIS. I know I should, but I already have two airspeeds and two altimeters.

Any help on why the heading would take off the wrong way would surely be appreciated!

Thanks,

Dave Adams
Long EZ N83DT
Race 83

 

[dynonsupport]

Re: Autopilot/EDC10A Installation - Heading Proble

The EFIS requires airspeed to work properly, and always has. It uses this as part of the math for roll and pitch. Without this, all bets are off, especially in a long turn. Beyond that, the AP requires airspeed in order to keep the aircraft within the airspeed limits- even a modern standalone AP requires pitot.

You can hook a GPS up as a backup source of airspeed, but we still prefer to use real airspeed when it is possible.

I realize you don't have pitch in this case, but for other installs, without static hooked up, there is often some change in cockpit static with airspeed, so if it tries to hold altitude, it will have some issues in that department too, since the altitude will vary with airspeed, and airspeed varies with pitch, so you get this big nasty loop.

I think you'll find it all comes together when you hook up your plumbing.

 

[longezdave]

Re: Autopilot/EDC10A Installation - Heading Proble

Thanks, I'll hook up the plumbing. I just didn't see the connection with heading.

 

[longezdave]

Re: Autopilot/EDC10A Installation - Heading Proble

Hooked up the plumbing and I'm very happy now. It worked great except for at the end of a 180. It kept banking back and forth 20 or 30 degrees and didn't seem to be dampening out closer to the desired heading. No problem - I don't expect to be using that feature very often!

Thanks!

 

[longezdave]

Re: Autopilot/EDC10A Installation - Heading Proble

I posted too soon. I only got to try it briefly before that last post. I tried again yesterday and the AP only held heading a few times. Usually it would hunt back and forth past the desired heading and not settle out. I tried different settings on sensitivity (lowest worked best) and max bank angle and could not come up with a winning combo.

It seems the problem is the indicated heading. When the plane banks, the indicated heading changes and it also changes with pitch changes.

Maybe I missed something in the setup. Any ideas?

Thanks!

 

[dynonsupport]

Re: Autopilot/EDC10A Installation - Heading Proble

If the indicated heading is not behaving properly, then then heading-based AP is going to perform poorly as well. So I'd look at the EDC installation/calibration to start. Give us a call at 425-402-0433 if you want some pointers on typical setup issues there.

 

[longezdave]

Re: Autopilot/EDC10A Installation - Heading Proble

When I get time, I'll go back through the EDC installation/calibration. If I don't figure it out, I'll give you a call.

Thanks!