Heading overshoot only in nav mode

[Solana]

Dynon support,

I think I have my autopilot pretty well calibrated. In heading mode it rolls out on heading perfectly. In nav mode, when it comes to a turn in the flight plan it overshoots the heading by fairly consistent 5°. Can you explain it and suggest a solution?

Thanks,

Rick Solana

 

[Dynon]

Here are two possibilities/things to look at:

In NAV mode, the AP won't sequence until it hits the new waypoint and will always overshoot, unless the anticipate turns feature is on. Another is that changes in TRK mode can look funny if you're watching the HEADING (not the track) and it's windy. But from what you've described, it may be the first one.

 

[breister]

Here are two possibilities/things to look at:

In NAV mode, the AP won't sequence until it hits the new waypoint and will always overshoot, unless the anticipate turns feature is on. Another is that changes in TRK mode can look funny if you're watching the HEADING (not the track) and it's windy. But from what you've described, it may be the first one.

Is that also true with an NMEA source such as a Garmin 635? I seem to recall that such radios automatically commanded lead-turn, but perhaps your unit ignores steering commands and generates its own based on flight plan?

Also, how does that work for approaches? I would think the Garmin (or similar units) would be commanding both pitch and steering commands in that mode?

 

[Dynon]

Granted, I was assuming NAV mode against our own flight planning engine. When using an external navigator, it totally depends on what the device outputs. Some units do indeed have turn anticipation and send GPS steering commands to suit. That anticipation is often depicted on the flight plan.