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Unusual autopilot behaviour?

Featured Replies

Hi Folks

 

My AP is exhibiting some strange behaviour. I'm sitting on the ground and engage just the AP (without selecting the HDG, ALT, APR buttons etc) and the Pitch Trim Wheel starts adjusting by itself. Once I select and deselect the ALT button, it stops doing this and subsequent AP on and off doesn't cause this to happen. This is likely the reason I couldn't control the elevator with only HDG hold selected with the AP engaged earlier. Is this normal? I don't recall it behaving like this before.

 

Cheers, Al

Is this normal?

 

I dunno? Why would I want to turn the autopilot on if I was sitting on the ground? <--that's a serious question Why would I turn on the autopilot if I was sitting on the ground? :huh:

Why would I want to turn the autopilot on if I was sitting on the ground?

 

That was exactly my first thought, but the A2A B377 Stratocruiser checklists have you turning the autopilot on during part of the run-up phase. I have no idea why.

 

Hook

Larry Hookins

 

Oh! I have slipped the surly bonds of Earth
And danced the skies on laughter-silvered wings;

  • Author

Hi Guys

 

Actually what I was doing was trying to troubleshoot why I didn't have elevator control with just HDG selected and the AP engaged. So I was just sitting there and thought what would happen if I engaged the AP - which prompted my question. So let me rephrase my question. I thought with just AP engaged on HDG mode, I was responsible for the altitude aspect while the AP took care of the direction the heading was set to. But when configured that way I had no elevator control suggesting the AP had control of it. Any idea why this should happen?

 

cheers, Al

Look in your aircraft.cfg for the [autopilot] section.

 

In that section look for default_pitch_mode.

 

The available settings are...

=0- none

=1- Pitch Hold (current pitch angle)

=2- Altitude Hold (current altitude)

 

If that parameter does not exist FS will default to =1.

 

If you want pitch control change that line to =0 if it exists or add it if it does not.

 

You can also have default_bank_mode.

 

The available settings are...

=0- none

=1- Wing Level Hold

=2- Heading Hold (current heading)

 

Again, if that line is not there the sim will default to =1.

 

regards,

Joe

The best gift you can give your children is your time.

sigbar.gif

  • Author

Thx Joe

 

I checked out a couple of the aircraft.cfg files and neither of those entries were in there. I added the default_pitch_mode=0 to the C172 cfg file and that fixed the problem.

 

cheers, Al

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