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Dragn

C172 AP hdg function backwards

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Hi all,

  Tried the AP in the C172 today and though the altitude hold worked I found the heading bug and compass did not.  I was flying from 3W5 Concrete back towards the coast to Anacortes.   I was flying mostly West but the compass showed I was flying East.  Tried to set the hdg bug straight ahead and couldn't figure out why the aircraft wanted to make a 180 turn!  Then I realized the heading on the compass showed East when I was flying West.  Anyone know of this bug, or is it something I'm doing wrong?

Thankss


Robert Abernathy

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Did you align with the magnetic compass, I noticed once that it had swing 180 degrees, try pressing d to see if it's a mega drift issue

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Wayne such

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C152/172 Heading Indicator drift is unrealistic. I dealt with drift in my real flying, but nothing like this. I finally had to change the game settings to stop compass drift.  Oddly, with drift setting changed it can still be misaligned from time to time. Not by much and not too often... but I like that it still needs to be part of your check list and flight management. "d" key is helpful to align in busy times.

Enjoy the flying.

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Thanks a lot for the ideas.   Didn't realize the "d" key would be the same in MSFS.  Worked well, although I couldn't find the setting for turning off compass drift. 

Something interesting I discovered.  I'm probably the last one to the party but using FSGet and Google Earth works a treat in MSFS!


Robert Abernathy

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5 minutes ago, Dragn said:

Thanks a lot for the ideas.   Didn't realize the "d" key would be the same in MSFS.  Worked well, although I couldn't find the setting for turning off compass drift. 

Something interesting I discovered.  I'm probably the last one to the party but using FSGet and Google Earth works a treat in MSFS!

What is fsget and how does it relate to google


Wayne such

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The heading indicator tends to heavily drift when during Active Pause, consider normal pause (via key assignments) or Esc to menu instead. 

Always align the heading indicator with the magnetic compass (and the known runway direction) when on the runway before the takeoff (you ned enough engine power for the vacuum system powering the heading indicator gyro). 

Edited by Steku
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Thanks for the advice Steku.  I'll make that part of my initial checklist now.

Jetman67, fsGet is a small program that allows an interface between FSX, P3Dv4-5 that shows the position of your aircraft in Google Earth.  Allows you to follow along wherever you go and helps me to look around for points of interest, other airports, and how it should really look like.  With Orbx True Earth series there is no guessing but with other sceneries it helps to know what should be there IRL.

A google search for fsGet with give you the link.  I believe it works with simconnect.  Works for FSX, P3D already but I was surprised that it linked to MSFS right away without doing any different setup work.

 


Robert Abernathy

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Little Navmap works perfectly with MSFS as well. It also displays all of the AI traffic too!


Fr. Bill    

AOPA Member: 07141481 AARP Member: 3209010556

Interests: Gauge Programming - 3d Modeling for Milviz

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18 minutes ago, Dragn said:

Thanks for the advice Steku.  I'll make that part of my initial checklist now.

Jetman67, fsGet is a small program that allows an interface between FSX, P3Dv4-5 that shows the position of your aircraft in Google Earth.  Allows you to follow along wherever you go and helps me to look around for points of interest, other airports, and how it should really look like.  With Orbx True Earth series there is no guessing but with other sceneries it helps to know what should be there IRL.

A google search for fsGet with give you the link.  I believe it works with simconnect.  Works for FSX, P3D already but I was surprised that it linked to MSFS right away without doing any different setup work.

 

Thanks very much


Wayne such

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Just look at the compass and adjust you heading indicator.

And those who like realism you have never flown with broken HSI gyro it precesses like crazy. So consider it real life  failure simulation 🙂

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flight sim addict, airplane owner, CFI

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On 9/8/2020 at 6:14 AM, Jim Jelf said:

C152/172 Heading Indicator drift is unrealistic. I dealt with drift in my real flying, but nothing like this. I finally had to change the game settings to stop compass drift.  Oddly, with drift setting changed it can still be misaligned from time to time. Not by much and not too often... but I like that it still needs to be part of your check list and flight management. "d" key is helpful to align in busy times.

Enjoy the flying.

I haven’t had any drift issues - in fact I’ve had the opposite issue. It never really seems to drift much at all. And I have my assistance settings all off.

 

Also, is it realistic for the autopilot to track the magnetic compass heading that you enter on the heading indicator and not the bug itself?? I’ve never used the AP on the real C172 but I can’t imagine that is how it works.

 

When I misaligned my heading indicator from the mag compass, set the heading bug to straight ahead, and pressed HDG on the autopilot, the plane immediately turned away so that the mag compass showed the same heading as the bug was marked on the heading indicator...

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I turned ON the Drift Assist. It appears there is drift, but much more realistic - the way it should be I think.

In a small Cessna, AP and Mag compass don't work directly together. Compass is like any using the earth's magnetic field. The loss of all power or other Instruments will not affect the compass. I'm not sure how you were setup, but alignment to the compass is manually done. And the AP has no connection to the compass

Try this for testing: Taxi the plane on the runway (27 for example), center line. Let the compass settle for a few seconds and verify it is within a few degrees. Align your Indicator to the Compass. Adjust the Indicators heading bug to the same direction of 27 +-.

Next, be sure AP is disengaged and preset an ALT (if you want). Take Off and level out. Engage AP, then HDG. The plane should hold that 27 heading or if you are off a bit, will turn to 27. Optionally, engage your AP ALT hold or rate of climb to your preset Altitude. That's about it.

If you still see an abrupt deviation, be sure sure you don't have a conflict programmed in your controls. I had a button on my stick wrong and when I hit AP my plane would go crazy. Drove me nuts! LOL

Enjoy the flying!

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