C-182 "Riding the wave" and autopilot tracking issue

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Subwofer2
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C-182 "Riding the wave" and autopilot tracking issue

Post by Subwofer2 »

I believe both of my concerns have been corrected. The community was great to help me this far - greatly appreciate the input, always nice to have another set of eyes on an issue. Completed another flight today without these problems and on a 1000 nm over ocean flight now, running beautifully.

Hello,

Thanks in advance for your assistance. I do hope what I'm experiencing has been previously seen though I was unable to locate any helpful previous posts, not to say they do not exist.

System Details:
HP EliteBook Folio 9480m - 8 GB memory - Intel(R) Core(TM) i5-4310U CPU @ 2.00GHz
FSX Gold - Acceleration is active
FSUIPC4 Full
AS16
Little Nav Map
ORBX Everything
SPAD (not Next) - Radio Panel - Multi Panel - Switch Panel
Alpha Yoke
CH Pedals and x2 Throttle Quadrants (CH Products Fighterstick and Pro Throttle USB - inactive via FSUIPC4)
Controls/Panels connected via x2 USB hubs
Accu-Feel (Global in on, Aircraft is Off)
Latest Accu-Sim Update 11/05/2020 applied - (aircraft installed - loaded sim, loaded aircraft, shutdown FSX - ran updater)

I've confirmed there are no control assignments in FSX associated with any of the controls above. I've not seen any of the same issues before with any other aircraft, including all other A2A add-on aircraft (with the exception of the Civilian Mustang - I have all other A2A products available for FSX on the website today). I have not spent much time in the Cherokee 180 or C-172 but do not recall experiencing the "wave" in these aircraft except for possibly once during a runup with the 180, maybe the 172.

x2 Issues being experienced:

1. "The Wave"
Videos to help illustrate:
https://youtu.be/mkQVDWjtLAk (no autopilot - begins as the video starts, another just after 1 minute)
https://youtu.be/FZOl67vrQqg (with autopilot enabled - starts after an event - next is after 1:40)

I have experienced this both on the ground and in the air - it's as if a wave of water is pushing the C-182. On the ground such as during run-up/slow taxi (and not every time), it cannot always be overcome quickly with brake inputs and as you can see in the video (sorry for the poor quality). In the air, this accelerates the aircraft and makes it nearly unflyable - requiring a great deal of control inputs/trim adjustments in what should be cruise without autopilot. It also happens in the landing phase. This has occurred on all flights (11 hours total) yet not with any measurable frequency from one to another (can go as much as 45 minutes but usually will occur in the landing... but not always). You'll notice in the videos - the manifold pressure and fuel flow all remain constant.

UPDATE: the throttle can be seen fluttering and there is a noticeable RPM increase (I failed to recognize this, thank you Flapman for noting times). I now suspect this is due to a dirty signal from the throttle quadrant/hub/mouse nest of controller wires, there may not be much I can do to clean this up. I had filtering enabled in FSUPIC but disabled it - currently 30 minutes into a flight AP Nav GPS is active - AS16 is running - FPS ~11 and I've yet to experience a "wave".

2. Autopilot Nav and Heading Tracking
I've read of the importance of having the heading bug aligned with the course so on the last two flights I tested this but do still have an issue tracking with NAV enabled - it will track initially but at a point - it will deviate from course, even as much as 180 degree and track away from the destination before returning to track to the intended. This is using a LNM flight plan exported/imported to FSX and using GPS mode on the panel.

Additionally... it will not always track to the Heading. The display on the Multi Panel for course and heading does match to those displayed on the panel.

UPDATE: I managed to complete a flight of 120 nm without a heading deviation - AS16 was not active, no other change. Per Oliver's recommendation. I will try an return flight with AS16 but decease the up and down draft settings. What I've seen as possibly being helpful is to set the heading bug and course to the exact same degree using the multi panel before departure. I'll try some multi heading legs in the future where changes must be made enroute and report back.

My original goal of adding the 182 to the sim hanger was for use in IFR approaches, currently... it difficult enough in VFR unfortunately.
C-182 NAV Track 1.png
C-182 NAV Track 1.png (366.32 KiB) Viewed 4108 times
1st image - tracking to TOC, 180 turn, autopilot continued climb and reacquired course - heading bug not aligned with course
C-182 NAV Track 2.png
C-182 NAV Track 2.png (631.65 KiB) Viewed 4108 times
2nd image - continued tracking to destination after TOC, left course before TOD and returned. ~12 miles after TOD, it again started a turn, at this point autopilot was disengaged.
C-182 NAV Track 3.png
C-182 NAV Track 3.png (110.03 KiB) Viewed 4108 times
3rd image - lower overlapping lines shows tracking between two airports - this is with the heading indicator aligned with the course, it is also the same track when the videos were recorded)
Last edited by Subwofer2 on 19 Jan 2022, 10:50, edited 7 times in total.
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MkIV Hvd
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Re: C-182 "Riding the wave" and autopilot tracking issue

Post by MkIV Hvd »

Hello,

It's hard to see what you're referring to in the videos, but my gut feeling is that your frame rates are far too poor for the autopilot to work properly if at all. I think I remember seeing around here somewhere that ~20-25 FPS was needed for smooth operation of the AP, but your FPS appears to me to be in the single digit range...

Good Luck & Cheers,
Rob
Rob Wilkinson
A2A: Civilian Mustang, T-6, Bonanza, Comanche, Cub, C182, Spitfire, P-40, Cherokee, P-51 - VATSIM P4 and some other stuff...

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Subwofer2
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Re: C-182 "Riding the wave" and autopilot tracking issue

Post by Subwofer2 »

Thanks Rob,

The video FPS are terrible, no idea why its so bad, I agree... sim rates are likely above 20. That said, autopilot has always worked in every other aircraft including ALL A2A aircraft installed. If you watch the airspeed indicator and review the text, what I experience and is shown in the video may be more noticeable.
Last edited by Subwofer2 on 18 Jan 2022, 15:34, edited 1 time in total.

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Oliver Branaschky
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Re: C-182 "Riding the wave" and autopilot tracking issue

Post by Oliver Branaschky »

What you refer to as “the wave” sure enough looks like a thermal updraft introduced by AS16. This tends to be way too pronounced. Try without AS, and if that rectifies the problem, try limiting updraft in the AS settings. IIRC, I’ve set mine to 500 ft/min or even 200 max. Good luck.

As to the AP issue, my first guess, too, was frame rate. But since that’s not the problem here, I’m sure that others will chime in.

All the best.

Cheers,
Oliver

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Subwofer2
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Re: C-182 "Riding the wave" and autopilot tracking issue

Post by Subwofer2 »

Thanks Oliver, I've reviewed my up and downdraft settings, currently set to 1500, I'll try again without AS16 and see what is experienced.

Is it possible the C-182 can somehow be affected differently as this is not experienced in any other A2A aircraft?

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Subwofer2
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Re: C-182 "Riding the wave" and autopilot tracking issue

Post by Subwofer2 »

Just began a test with AS16 turned off, FSX weather setting of clear skies.... still riding the wave. I did notice my frames drop below 10 while recording and are in the 12-15 range otherwise. Also - I'm wondering if there is substantial signal noise being picked up from the controls and read as inputs via FUSIPC.... trying to watch the axis log for an input looks like something out of the Matrix movie.

https://youtu.be/eJuAKZdzkt0 - "wave" even at in process at beginning, another @ 1:20 and 1:40 - this time I noticed the RPM does flutter also.

I've not yet tried to use the A2A Input Configurator.... new things scare me, that said - reviewing it - there is not an option for throttle/prop/mixture inputs.
Last edited by Subwofer2 on 18 Jan 2022, 18:22, edited 2 times in total.

flapman
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Joined: 10 Oct 2013, 21:35

Re: C-182 "Riding the wave" and autopilot tracking issue

Post by flapman »

I don't own the 182 (I have the 172). Only thing I can add is that in your first video... immediately before each airspeed increase, I observe the cockpit throttle snapping to idle for an instant, then returning back to the previous position.

https://www.youtube.com/watch?v=mkQVDWjtLAk
@00:47
@01:01
@01:17
@01:31
@01:46
@01:56-57

perhaps it's also spiking to full throttle, and we don't see that animated?

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Subwofer2
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Re: C-182 "Riding the wave" and autopilot tracking issue

Post by Subwofer2 »

Thanks flapman, I agree and will update the original post also - I suspect it due to a dirty signal from the throttle quadrant/hub/mouse nest of controller wires, there may not be much I can do to clean this up.

Completed a flight from Nausori Intl (NFNA) to Cicia Airstrip (NFCI) - 120+ nm and the autopilot remained on course with AS16 off - a first.

https://youtu.be/u7OdktOSvDU

Staggeringly slow frame rates.... I need a new machine and look forward to P3D as well.

I wonder if I can have a floating "null zone" for the throttle/prop/mixture settings in FSUPIC to reduce the noise?

flapman
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Re: C-182 "Riding the wave" and autopilot tracking issue

Post by flapman »

I also notice you have an absolutely enormous density of trees... even compared to my FSX which is on (what I consider) a capable machine.

Perhaps, at least for your tests... try aggressively rolling back your graphic settings to target something like 40+ FPS. You can very easily save your current settings, and then load them again after the test is over.

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Subwofer2
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Re: C-182 "Riding the wave" and autopilot tracking issue

Post by Subwofer2 »

Great advice, I've seen mid 20s recently but made some changes Sunday morning and had not yet returned them... made adjustments, looking forward to running another flight tomorrow.

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Subwofer2
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Re: C-182 "Riding the wave" and autopilot tracking issue

Post by Subwofer2 »

Very grateful to report two flights completed today - no issues! The 1st was nearly 200 nm... the 2nd... 1125 nm. Both with AS16 running and neither of these issues surfaced during the flights! Fantastic! Next flight, off to Tapini!
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