Altitude hold...

[BlueCH750]

In Phase I flight testing and starting to inflight tune the AP servos.  Using the Dynon produced flow charts for  inflight tuning.  Two SV32 servos installed on STOL CH750 along with AP control panel.  In simplified mode TRK/ALT along with HSI/ALT seem to hold altitude OK (smooth air).  When switching to expert mode, airspeed hold seems to do quite well (smooth air).  Coming out of the IAS mode into ALT hold, the autopilot will start deviating and correcting either side of the altitude until it seems to give up and drift either way from the engaged altitude.  Could this be related to my ALT bug?  All thoughts appreciated....thanks!

 

[Raymo]

I'm not sure it is related to your problem but in Expert mode, when you change the ALT bug, you then have to tell the AP to go there via the up or down button. Subsequent pushes will increase or decrease the rate of descent or climb.

 

[BlueCH750]

Thanks Ray, I did not glean that from the literature, will give it a try and see if it "helps" the autopilot find it's way! :

 

[Dynon]

Also, confirm that you're actually in altitude hold mode. Once you've transitioned to altitude hold mode in expert mode, that altitude being tracked is in the AP status area, but the bug itself is then freed up so that you can select another altitude to go to once you initiate a climb or descent via either the up, down, or VS/IAS mode buttons.

 

[BlueCH750]

OK, thanks Dynon, will have a chance to further flight test later this week.