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Author Topic: PM AT issues found and solution ( throttle hunting and overspeed )  (Read 1832 times)

Offline GSalden

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For years now people are suffering from issues with the PM AT below 11.000ft : speed 10-15 kmnots too high and throttle hunting .
For 3 weeks I have worked on a customized flightmodel. Perfet landing with flare manually but not with Autolanding.

If I wanted to do an Autolanding I had to set the mcp speed 15 knots lower than the matching flaps speeds.
Below 500 ft I set the final flap with Vref - 5 instead of Vref + 5 and the landing then went very smooth. 
 
Bernhard here at Cockpitbuilders found that weather had a great influence on the AT at approach.
If he turned of his weather engine he could make a good autolanding and the aircraft kept the dialed speed instead of throttle hunting and speeds that stayed 10-15 knots above the dialed mcp speed.

I have been testing this too :
•Turbulence Off in the FSX/ P3D menu and no weather engine --> no heavy throttle hunting and the AT keeps the dialed mcp speed
•Weather engine On and throttle hunting occurs 


Solution for now :
•In ASN / Opus :  all turbulence Off ( wind, cloud, wake )
•In Fs  Turbulence Off
•FSX.cfg/P3D.cfg : Turbulence values have to be set to 50% their default value
•In Fsuipc :  surpress guts/windshear/turbulence

These are the same adjustments that were advised just after the release of the PMDG 737 ( S-tuning/up/down pitching at approach ).
Later they made changes to their mcp gauge.

PM never had the issue in Fs2004. Probably as weather injecting was still very basic.
When FSX came out many people had these issues.

Imho PM has turned off turbulence in their simulator as in all flying vids the aircraft never suffers form turbulence.
They probably never thought about the turbulence which other people had set to high values....


The default PM 737-800 does not work correct on my system : overspeed on descent and not the right "737"feeling according to my judgement. I made some adjustments to my custom made airfile regarding drag/lift and now I can make nice Autolandings.
When making a flight I will land manually , but for me everything has to work when if the feature exists.

The last thing I have to do is look into the throttles retard as that does not happen correctly.
With only the onscreen throttles the throttles go back to idle slowly after landing.
When using my motorized Cockpitsonic tq they do not go back to idle at all.

If anyone has the solution for this let me know.
If that has been fixed  too I will upload the total PM 737-800 package for download.

Regards,
Gerard 
« Last Edit: December 04, 2015, 01:51:13 PM by GSalden »

Offline jr2mey

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Re: PM AT issues found and solution ( throttle hunting and overspeed )
« Reply #1 on: August 23, 2017, 11:56:45 AM »
Hello Gerard,

I was wondering if you managed to solve your 737 config issues.  I too use PM with their 737 flight model and have always been experiencing the same issues.

Regards,
James

James

Offline Bob Reed

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Re: PM AT issues found and solution ( throttle hunting and overspeed )
« Reply #2 on: August 23, 2017, 12:22:17 PM »
I too would be interacted in this as I use PM.

Offline Patt737

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Re: PM AT issues found and solution ( throttle hunting and overspeed )
« Reply #3 on: February 01, 2018, 02:00:14 PM »
Hello everyone,

We have been experiencing the same problem since we started p3d v3.
It worked well with the fs9 autopilot.

Can you tell us what are the drag / lift values you have changed.

What new values did you give?

Thank you .

Patt.

Offline Bob Reed

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Re: PM AT issues found and solution ( throttle hunting and overspeed )
« Reply #4 on: February 05, 2018, 08:26:29 AM »
Hello everyone,

We have been experiencing the same problem since we started p3d v3.
It worked well with the fs9 autopilot.

Can you tell us what are the drag / lift values you have changed.

What new values did you give?

Thank you .

Patt.

Mr Saldon has not been on the board since Nov 19th 2016. I do not think there will be an answer from him. :) Anyone else have an answer?
« Last Edit: February 05, 2018, 08:27:06 AM by Bob Reed »

Offline Patt737

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Re: PM AT issues found and solution ( throttle hunting and overspeed )
« Reply #5 on: February 06, 2018, 01:39:36 PM »
Hello,
Thank you for help.
I suspected, but I tried.
I'm going to open another post because I have another question.

Patt

Offline Pantu

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Re: PM AT issues found and solution ( throttle hunting and overspeed )
« Reply #6 on: August 30, 2018, 06:29:34 AM »
Hi,
 :2cw:
sorry for bringing up this older subject again. Havin read lots of posts over on the old PM Forum at mycockpit.org I found some FSUIPC v5 mod. concerning this thread´s subject.(Speed problems with PM MCP).
Since it has not been mentioned here yet (afaik) I´d like to let you all know about this. Could well be that some have heard of it already, then just ignore.
Here it is, the relevant excerpt of the FSUIPC v5 guide for advanced users:

FiddleMachForPM=Yes is, hopefully, a temporary fix for Project Magenta users who suffer the problem of high speed descents
under MCP control as a result of PM incorrectly setting a Mach speed in the wrong mode. This only affects P3D adversely because of
the odd way FS9 and before worked, for which PM was originally designed. To enable this fix add this parameter (it won’t appear in
the INI by default).
By way of explanation, when the PM MCP sets the IAS for the A/P it also sets the Mach value. This would be okay, except for three
things:
1. The Mach value it sets after cruise is ALWAYS the last one it set in cruise, not a correct one related to the IAS and
altitude/temperature/pressure.
2. The Mach is written after the IAS
3. In FS9 and before, the Mach setting did not affect the IAS setting nor vice versa until and unless you switched IAS/Mach modes. However,
in FSX and later the last-written value applies and is converted to the equivalent IAS/Mach no matter which mode you are in!
This FSUIPC5.INI parameter simply makes FSUIPC discard any MACH writes whilst the PM MCP is in IAS mode.

FiddleAppAltForPM=Yes is another hopefully temporary fix for Project Magenta. It makes FSUIPC automatically replace any
altitude written during PM MCP APP mode by zero. It also sets the P3D MCP altitude to zero in PM MCP APP mode when a negative
VS is set, and it does both these things even if Altitude Hold is enabled.

The intention here is to avoid any unwanted climbs when descending on the GlideSlope due to the fact that FSX seems to be different
to FS9 and before in that writing to the FS MCP's altitude register can affect the requested vertical speed even though FS’s altitude
hold option is not enabled.

Cheers

Pete

Offline Trevor Hale

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Re: PM AT issues found and solution ( throttle hunting and overspeed )
« Reply #7 on: August 30, 2018, 09:58:40 AM »
Pete, a great post.  thanks I will need to look into this further.
Have a great day!
Trevor Hale

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