MartinRex007

Auto pilot odd behavior

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I'm having some odd moments with this AP. Before takeoff I set the Alt Alert to say 9,000ft and arm it, then hit the FD and HDG on the AP. Takeoff set things up for climb out and hit the AP on the mode selector and nothing happens in either the VC or popup, only way to get the AP on is to hit the Z key.  At this point everything seems fine. The problem happens when I hit Nav on the mode selector to follow my GPS route in the GTN750. Nav lights up along with Nav1 and GS? Then my pitch goes crazy and the plane goes into a sharp climb and stalls. Any insight into what might be going on would be very much appreciated..

Thanks

Martin

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5 minutes ago, MartinRex007 said:

I'm having some odd moments with this AP. Before takeoff I set the Alt Alert to say 9,000ft and arm it, then hit the FD and HDG on the AP. Takeoff set things up for climb out and hit the AP on the mode selector and nothing happens in either the VC or popup, only way to get the AP on is to hit the Z key.  At this point everything seems fine. The problem happens when I hit Nav on the mode selector to follow my GPS route in the GTN750. Nav lights up along with Nav1 and GS? Then my pitch goes crazy and the plane goes into a sharp climb and stalls. Any insight into what might be going on would be very much appreciated..

Thanks

Martin

Which GTN750..Flight1 or RealityXP?

 

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Fligh1 and I changed the aircraft to 4 in the .ini as mentioned earlier by Bert?

The only thing I can think of is maybe when I hit Nav it used Nav2 which it looks like it defaulted too and that messed things up, I'm trying another flight to see if that was the problem.

I'm probably doing something wrong, but couldn't find any documentation from Alabeo.

P.S. is there a way to set the default Nav to Nav1?

Edited by MartinRex007

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Couple of things..

The AP indicator on the autopilot control panel is just that, an indicator.

The AP on/off switch is on the lower console (or you can use the Z key, as you discovered).

The GS light should only light up if you have a vertical signal on the HSI, ie a glideslope..  This could happen if the GTN is in VLOC mode and you have an ILS frequency dialed in, or if the GTN is in GPS mode and an LPV approach is active..  If this occurs again, post the details!

The upper right switch is the NAV1/2 switch!  The NAV on/off switch is the middle switch.  You'll get used to it..  Agree that some documentation would come in handy!  I purchased the factory autopilot manual, so if you have detail questions, contact me via PM..

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Bert,

Thanks for this info, yes I thought it odd that GS would show up when I hit Nav, will continue to run some test.

Cheers

Martin

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I took of from MMLT with no other airports around for miles and same thing, when I hit Nav to track my GPS route, for some reason the GS indicator comes on and the plane loses pitch control and stalls. Nav2 also comes on, but I can quickly hit Nav1 instead but can't seem to do anything with GS being on?

Thanks Martin

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The GTN has an active flight plan and is in GPS mode, correct?

I'll test and see.. worst case request my GTN panel via PM (with your email address) as a test.

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Correct, a GPS route I do often in other Carenado aircraft with no problem.

Thanks Bert, let me try one more thing.

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Strange, I just tested the unmodified V1.1. version and VOR and NAV1 lights up, as expected.

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Whenever I hit the Nav switch to follow the GPS route the GS comes on, Nav1 lights, and GPS set correctly....once the GS lights the plane loses control.

I sent you a PM

 

Thanks - Martin

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The AP800B works fine when using a VOR as your Nav source, but when I try and use the GTN 750 GPS as the Nav source is when the GS comes on and everything goes crazy...ugh! Back to the good old days of flying from VOR to VOR!  Off too Vegas to attend the Expo, should be fun!

Cheers

Martin

Edited by MartinRex007

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54 minutes ago, MartinRex007 said:

The AP800B works fine when using a VOR as your Nav source, but when I try and use the GTN 750 GPS as the Nav source is when the GS comes on and everything goes crazy...ugh! Back to the good old days of flying from VOR to VOR!  Off too Vegas to attend the Expo, should be fun!

Cheers

Martin

This must be fixable.. it works just fine on my system..

Let me know when you return!

Enjoy Vegas.. :cool:

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That behaviour is realistic. Those old 800B autopilots are known for their strange failures and it is difficult and expensive to repair them. 

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21 hours ago, AndiKunzi said:

That behaviour is realistic. Those old 800B autopilots are known for their strange failures and it is difficult and expensive to repair them. 

Sure would be nice if someone could drop us an STec in there with preselect. I used to have FS panelshop, but I don't know if it still works for P3d... 🙂

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N100L has an S-Tec 60-2 (similar to the 55X) with Altitude Preselect via the Aspen EFD1000. 

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If I track to a VOR after takeoff (which works fine) then change nav source to my GPS route the AP picks up the route with no problem, but if I takeoff and turn to a heading for a GPS route first and hit NAV on the AP the GS comes on and the plane loses control, very odd. Still have some more testing to do but I can live with this little anomaly.

Cheers

Martin

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Just now, MartinRex007 said:

If I track to a VOR after takeoff (which works fine) then change nav source to my GPS route the AP picks up the route with no problem, but if I takeoff and turn to a heading for a GPS route first and hit NAV on the AP the GS comes on and the plane loses control, very odd. Still have some more testing to do but I can live with this little anomaly.

Cheers

Martin

I have looked at the autopilot code.. When you push the NAV button, the autopilot switches on:  NAV or APR, depending on whether the nav source has a localizer active.  That sounds kind of logical, but could go wrong depending on the variables, as you are experiencing.   Give me your email address and I'll send you a mod with this option disabled.. that might just work better for you.

Interestingly, I have not run into this, but that may depend on what NAV1 is tuned to at the moment that the NAV button is pushed..

If you can describe the exact scenario where you have this occur, I can try to duplicate it on my system and track some variables if required..

  • Upvote 1

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For anyone who likes to tinker with autopilot xml files, look in the Mouse section for the NAV button, and change

@Nav1Haslocalizer

to

@Nav1Haslocalizer  (A:GPS DRIVES NAV1, bool) ! and

That should prevent this from happening if GPS mode is active.

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Bert,

That fixed it, I sent you an e-mail explaining it in a little more detail, thanks so much for your help with this!

Regards

Martin

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Just now, MartinRex007 said:

Bert,

That fixed it, I sent you an e-mail explaining it in a little more detail, thanks so much for your help with this!

Regards

Martin

:smile:

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Assume one needs to extract the xml from the cab file?  Then how to subsequently position it properly?

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Just now, fppilot said:

Assume one needs to extract the xml from the cab file?  Then how to subsequently position it properly?

I create a subfolder to the panel folder with the same name as the cab file.

Extract the files(s) that you want to edit.

Drop the xml file(s) in the new subfolder and change their file name(s) by adding a character or two.

Reference the changed names in the panel.cfg file.

Example:

Folder name: AUTOPILOTO_C421

File name: Gauge_AUTOPILOT_C421_MSV4.xml

Panel.cfg file:  gauge01=AUTOPILOTO_C421!Gauge_AUTOPILOT_C421_MSV4,        0, 411,384,384

 

 

 

 

 

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And while you are at it.. change "or" to "and"..

<Element id="GS">
     <FloatPosition>0.000,0.000</FloatPosition>
     <Visibility>(A:AUTOPILOT APPROACH HOLD,BOOL) @Nav1GSIActive and (L:Gauge_TEST_C421_FD,number) 1 == or</Visibility>
     <Image id="Image" Name="Gauge_AUTOPILOT_C421_MS_GS.bmp">
                <Transparent>true</Transparent>
                <Bright>false</Bright>
            </Image>
     </Element>

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