KAP 140 autopilot FAQ

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jimjones
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Re: KAP 140 autopilot FAQ

Post jimjones »

Subject: Glidescope porpoising at various frame rates.

My PC runs at about 15-18 fps when the c127 is loaded and flying a glideslope with my usual settings, VC
showing. Excessive porpoising occurs.

Cutting back on several settings yielded about 38 fps and porpoising was much reduced but still when
close to landing it was excessive.

With those new settings and viewing the plane externally instead of via the VC the frame rate was about 95.
Porpoising was even less but still significant near landing.

One would think at an FPS of 95 the PC is not really struggling to perform its duties and that the
autopilot could perform its GS function accurately down to the point of landing.

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Lewis - A2A
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Re: KAP 140 autopilot FAQ

Post Lewis - A2A »

jimjones wrote:Subject: Glidescope porpoising at various frame rates.

My PC runs at about 15-18 fps when the c127 is loaded and flying a glideslope with my usual settings, VC
showing. Excessive porpoising occurs.

Cutting back on several settings yielded about 38 fps and porpoising was much reduced but still when
close to landing it was excessive.

With those new settings and viewing the plane externally instead of via the VC the frame rate was about 95.
Porpoising was even less but still significant near landing.

One would think at an FPS of 95 the PC is not really struggling to perform its duties and that the
autopilot could perform its GS function accurately down to the point of landing.

Hello jim,

there's an issue with degradation on the glide scope in 1.03 it will be fixed in next update. Also worth reading this thread as some users are trying to use the simple autopilot like a big jet one, also notes some flap and speed settings;
http://a2asimulations.com/forum/viewtop ... 08&t=37155

thanks,
Lewis


thanks,
Lewis
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LaFri
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Re: KAP 140 autopilot FAQ

Post LaFri »

Now with update 1.6, stable 30 fps and stable horizontal flight at 80 kts autopilot starts to porpoise if I accelerate to about 120 knots. I never had this in update 1.03. Has anybody else noticed porpoising at this speed?
Cheers, Fritz

LaFri
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Re: KAP 140 autopilot FAQ

Post LaFri »

To be more precise: porpoising happens only with 4 persons, about 30 kg luggage and a half gasolin on horizontal flight. As soon as I empty the luggage compartment porpoising stops.
Fritz

wrkempson
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Re: KAP 140 autopilot FAQ

Post wrkempson »

I have installed the 1.06 patch but still have a problem with porpoising with the autopilot. I select ALT and have the problem (even if I trim for level flight before engaging the AP). Engaging ARM finds the aircraft overshooting the selected altitude while basically ignoring my selected VS, resulting in the aquatic mammalian experience. Flying with no weather machinery does not help, nor does flying over default FSX scenery. Auto Rudder is off.

When engaging the AP, the ROL function kicks in, but all elevator and elevator trim control is immediately taken away from my controller. This is with both ALT and ARM disengaged. I could not find anywhere that stated that this is normal, but I just don't know about it.

I have a) read the KAP140 manual, b) uninstalled the aircraft, re-installed, then run the 1.06 patch (several times), c) disengaged the elevator trim from my controller, d) read all the posts on the forum I could find, e) called in a local shaman who has blown bone dust on my monitor.

I have run out of ideas to try. I am running Windows 7 with a 3.33 Ghz 64-Bit processor using a MS Sidewinder 2 joystick. At this point I would be thrilled to find out the problem is with my controller, but I don't want to go that route without someone's more expert advice.

Thank you for a great product.

Wayne

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lonewulf47
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Re: KAP 140 autopilot FAQ

Post lonewulf47 »

LaFri wrote:To be more precise: porpoising happens only with 4 persons, about 30 kg luggage and a half gasolin on horizontal flight. As soon as I empty the luggage compartment porpoising stops.
Fritz
Yes indeed, I can confirm that. We will be looking at it at a later stage. it's most likely a dampening issue on the pitch axis.
Oskar

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lonewulf47
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Re: KAP 140 autopilot FAQ

Post lonewulf47 »

wrkempson wrote:I have installed the 1.06 patch but still have a problem with porpoising with the autopilot. I select ALT and have the problem (even if I trim for level flight before engaging the AP). Engaging ARM finds the aircraft overshooting the selected altitude while basically ignoring my selected VS, resulting in the aquatic mammalian experience. Flying with no weather machinery does not help, nor does flying over default FSX scenery. Auto Rudder is off.
When engaging the AP, the ROL function kicks in, but all elevator and elevator trim control is immediately taken away from my controller. This is with both ALT and ARM disengaged. I could not find anywhere that stated that this is normal, but I just don't know about it.
I have a) read the KAP140 manual, b) uninstalled the aircraft, re-installed, then run the 1.06 patch (several times), c) disengaged the elevator trim from my controller, d) read all the posts on the forum I could find, e) called in a local shaman who has blown bone dust on my monitor.
I have run out of ideas to try. I am running Windows 7 with a 3.33 Ghz 64-Bit processor using a MS Sidewinder 2 joystick. At this point I would be thrilled to find out the problem is with my controller, but I don't want to go that route without someone's more expert advice.
Thank you for a great product.
Wayne,
Are you using a controller axis for elevator trim? If so this is the main culprit for the described behaviour. As practical a means it is for quick and easy elevator trim, it must be disabled when using the autopilot. An axis will always command its selected value whereas the autopilot uses trim to control altitude. Those two cannot work on the same axis if one is fixed through a controller. Trim will be reset to the value set by the axis each time you touch the controller. Therefore porpoising is immediately induced. As soon as the autopilot is switched on it indeed enters basic mode in ROL and PITCH, using lateral and vertical steering commands and therefore disconnects the controllers. I heavily propose using trim commands by UP and DOWN buttons.
Oskar

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wrkempson
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Re: KAP 140 autopilot FAQ

Post wrkempson »

LW47,

Thank you for your reply. It makes good sense. I have elevator trim assigned to two buttons, not axes, but I suppose the principle would be the same? See item c) in my original post. Nonetheless, tomorrow I will try again to make sure the controller has no relationship to the elevator trim. I'll let you know how things turn out. It's a bit late in the evening for me to try it now. Thanks again.

Wayne

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lonewulf47
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Re: KAP 140 autopilot FAQ

Post lonewulf47 »

wrkempson wrote:...Thank you for your reply. It makes good sense. I have elevator trim assigned to two buttons, not axes, but I suppose the principle would be the same? See item c) in my original post. Nonetheless, tomorrow I will try again to make sure the controller has no relationship to the elevator trim. I'll let you know how things turn out. It's a bit late in the evening for me to try it now. Thanks again.
Well, with buttons there shouldn't be any misbehaviour on the trim. They are just de-activated whenever the A/P is on. I use button trim all the time (standard assignment though FSX) and don't have any problem with that setup.
Oskar

ASUS MAXIMUS XI Hero, i9-9900K 8 Core OC 5.2 GHz, WIN10-64Bit, 32GB DDR5, Nvidia RTX 2080 Ti Strix, 2x 2 TB SSD M.2, 1x 2 TB SSD, 1 monitor 4k, AS4, EFB on remote PC

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Lewis - A2A
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Re: KAP 140 autopilot FAQ

Post Lewis - A2A »

The easiest way to take the controller out of the equation is to simply unplug it and then start up your sim. Then use the default keyboard and mouse yoke to get yourself into the air. Then you can be sure if its a controller spiking or something else.
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wrkempson
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Re: KAP 140 autopilot FAQ

Post wrkempson »

Well, I deactivated the trim buttons anyway (as I had previously) and the problem persisted. Then I unplugged the controller (again) and took off using the keyboard. It wasn't pretty at all, and the problem persisted.

When I observe the trim wheel, it is apparent that the AP waits until the target has been passed before starting to adjust the trim. This results in the constant cycle of over reaction leading to the ever increasing oscillations. I am using blue tooth keyboard and mouse, but that seems an unlikely source (a stray signal?).

Anyway, thanks for the insights. I think I have read on this forum where other folks have had their problem solved by these measures. I'll keep trying. Please let me know if something else occurs to you.

Meanwhile, I still think this is a great product that I would recommend. My problem just means I have to do more flying and less reading while in the air.

Wayne

wrkempson
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Re: KAP 140 autopilot FAQ

Post wrkempson »

Are there any settings in the aircraft.cfg file under the autopilot section that might affect this?

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renaissanceman
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Re: KAP 140 autopilot FAQ

Post renaissanceman »

Hi Wayne,

What frame rates are you getting. It seems like the majority of the porpoising problems since update 1.6 that are not controller related have had to do with low frame rates.

Jim
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wrkempson
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Re: KAP 140 autopilot FAQ

Post wrkempson »

Jim,

I am flying with default scenery, the clear sky weather configuration (no changes) and without the TrackIR. In other words, I have taken everything off that might affect fps. I have it set for 20 in FSX settings. I don't know how to get the actual read out on fps while in flight. Is there a display setting I can use? Thanks for your interest.

Wayne

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Lewis - A2A
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Re: KAP 140 autopilot FAQ

Post Lewis - A2A »

Hello,

20 is right at the lower end so if the system is changing up and down from this it could be the issue. You could try changing your frame limiter rate up a bit?

thanks,
Lewis
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