invernyx / md11-bugs

The official bug tracker for the TFDi Design MD-11
https://tfdidesign.com/md11.php
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[BUG] - Excessive nose up trim required on final when handflying #1474

Open OD-Emperor opened 3 months ago

OD-Emperor commented 3 months ago

Describe the bug

When disengaging AP there is a high amount of nose up trim required on final to remain stable

Steps to reproduce

Load the MD-11 GE F normally, fly any distance, and land using an ILS. On the ILS you will notice the AP commands a normal pitch trim. In the video supplied, you can see it's at about 9.0 on the proper VAPP speed.

AP is disengaged at 18 seconds and you can see it briefly flies normally and the position of the yoke indicates it was not trying to input any force on the yoke to maintain the approach path. A few seconds later and especially once I start to add inputs to the yoke it very quickly loses the glideslope when it shouldn't.

During this time I have to increase the nose up trim excessively to about 13.9 when the speed and wind conditions have not changed by a large amount.

In some instances I have had to trim to the max available deflection at 15.5 to control the aircraft.

This behaviour was not experienced prior to .62 and is still in .64 (where the video is from). I suspect it has something to do with the improved rotation behaviour.

This has happened now on 4 different flights in the MD11F GE, and I'm unsure if it translates to the other variants but I'm very sure it will considering they're all quite similar.

Video flight route/weight:

ROUTE: KIND/05L MAREO5 BDOCK DCT DJB DCT JHW J70 LVZ LENDY8 KJFK/31R

WEIGHTS

            EST      MAX     ACTUAL

PAX 4 ......

CARGO 81.1 ......

PAYLOAD 81.4 ......

ZFW 198.0 204.7 ......

FUEL 25.3 35.0 ...... POSS EXTRA 9.7

TOW 222.4 232.1 LDG......

LAW 208.7 218.4 ......


Also experienced this behaviour on the following flights:

NZAA/05R DCT PEBLU N759 GEMAC Q302 LIZZI DCT YMML/16

WEIGHTS

                           -------

               EST      MAX     ACTUAL

PAX 3 ......

CARGO 78.3 ......

PAYLOAD 78.5 ......

ZFW 195.1 204.7 ......

FUEL 43.5 52.9 ...... POSS EXTRA 9.4

TOW 237.7 247.1 LDG......

LAW 209.0 218.4 ......


PHNL/04R OPIHI3 CARRP A579 CROBY DCT 05N168W 00N171W 05S174W 10S177W 15S180E DCT IGAPI DCT 25S177E DCT NISET A578 KALAG EXOPI8D NZAA/05R

          WEIGHTS

                           -------

            EST      MAX     ACTUAL

PAX 4 ......

CARGO 75.4 ......

PAYLOAD 75.8 ......

ZFW 192.3 204.7 ......

FUEL 92.3 92.3 ...... POSS EXTRA 0.0

TOW 283.7 283.7 TOW......

LAW 207.0 218.4 ......


KTPA/19R ENDED2 LACEN DCT BRUTS Q118 THRSR Q79 SWAPP DCT HAGAL GIIBS3 KIND/23R

 WEIGHTS

                           -------

            EST      MAX     ACTUAL

PAX 3 ......

CARGO 72.0 ......

PAYLOAD 72.2 ......

ZFW 188.8 204.7 ......

FUEL 29.6 46.6 ...... POSS EXTRA 17.1

TOW 217.4 234.5 LDG......

LAW 201.3 218.4 ......

Expected behaviour

To fly using a reasonable amount of pitch trim not the max amount.

Evidence

https://youtu.be/OujaBcTUbPc

Simulator

Microsoft Flight Simulator 2020 (MSFS)

Agreement

joon44 commented 3 months ago

I agree. I also have very high trim settings above 12 units on short final

KJA1582 commented 3 months ago

I concur, 15.2 up to 15.4 ANU on final

ZFW: 189648 LW: 201.8 at touchdown Fuel: 12198 at touchdown

I do note that going manual, at LSAS release, the aircraft had no pitch moment other than what was used to release LSAS.

At the Gate, reentry of INIT data gave ZFWCG of 27.5, TOCG of 26.7, STAB TRIM at No Flex, F28, 0/0 Slope/Wind, 19C was hence calculated as 10.8

Topofdescent5 commented 3 months ago

Same here, every flight I can remember in the last few weeks I'm at almost or full back trim and pulling on the yoke just to stay away from 3 or 4 red PAPIs. I'm at the point of not flying it anymore, sadly

joon44 commented 2 months ago

No more a problem