All that is wrong with the MSFS Flight Model (Inertia, Stalling, Pitch Authority, Trim & Sensitivity)

This is part of the fun. But maybe you can not understand it. People are different.

Interesting charts! How did you make them? I think the red and yellow lines show “fake” inertia and the response time. Response time is easy: the short time between blue line goes up and red/yellow line goes up. In my experience the aerodynamics of Extra 330LT is to fast for MSFS 2020 response time - but this is not very relevant here.
The “fake” inertia is parameter *_stability. From the Asobo cfg files:
C172:
pitch_stability = 0.1
roll_stability = 0.1
yaw_stability = 0.1
B748:
pitch_stability = 0.5
roll_stability = 0.5
yaw_stability = 0.5

The B748 value is 5 times larger. My suggestion: Change the B748 stability values and verify my hypothesis.

1 Like

Nijntje91, at my Salty 747 flight model mod I have recognized the following: If I go into a descent of say -1000fpm before touch-down and if I set speed to say 160 kts, it can happen that I loose elevator control. That is, later I can not flare the airplane, I make a controlled flight into terrain. If I give a lot of thrust, I can get out of this situation.

See my video at https://youtu.be/MP944N9mpm4

In my case there was no “more then 1g acceleration” involved. Please tell me: this behavior of loosing control but getting no alarm (no stall horn, no stick shaker) can this happen in real life? In the video I got stick shaker, but if I go a little faster in descent I loose control and have CFIT without alarm.

  1. No.

  2. Do you see the contradiction? If you loose control it can’t be a CFIT.

2 Likes

Okay. I use the CFIT definition of german Wikipedia: “Die internationale Zivilluftfahrtkommission ICAO und das Commercial Aviation Safety Team definieren CFIT als Zusammenprall oder Beinahe-Zusammenprall eines im Flug befindlichen Luftfahrzeugs mit einer Land- oder Wasserfläche oder einem Hindernis, ohne dass es Anzeichen dafür gibt, dass zuvor die Beherrschung über das Luftfahrzeug verloren wurde.”
Translation: "The International Civil Aviation Commission (ICAO) and the Commercial Aviation Safety Team define CFIT as a collision or near-collision of an aircraft in flight with an area of land, water or an obstacle without any evidence that the aircraft has previously been lost control. "

This “the pilot has not recognized that he/she has lost control” is part of the CFIT definition. You can disagree to ICAO, no problem. Because of my job, I am not allowed to disagree to ICAO.

Did you comprehend what you read? That’s exactly the point!
You have lost control, that’s why you crashed. = uncontrolled flight into terrain.

Thankyou for the very long and fascinating post.

Fingers crossed that the developers respond

2 Likes

Do you see the difference between “I know that I have lost control” and “I don’t know that I have lost control”? For me these are two different situations, even if they have the common fact of “lost control”.

I talk about CFIT. I have never heard of UCFIT (?) or UFIT (?) before in air traffic control.

If you are trying to pull up and the aircraft doesn’t respond, you know that you have lost control = no CFIT.

I agree. But if you descent before touch-down, you do not pull the stick. At the moment you want to flare, you pull the stick. If you recognize in this very moment that you have lost control (some time ago without your recognition) you can not avoid the rough landing or the crash.

I always have to perform small push/pull correction during the approach.
A loss of the ability to pitch up would be immediately apparent.

Anyway, since this is way OT, I’m going to leave it at that.

What weight? Is the aircraft flying at the stall speed? Otherwise it shouldn’t do that, when in trim descending at 1000 ft/min the stabiliser is trimmed for that situation but the elevator should have enough authority to flare I would say.

Edit: looking at your video you are flying at the stalling AOA in clean configuration so that seems normal… Not familiar with the B748 stall speeds though…

Didn’t watch the video but he wrote: loosing control but getting no alarm (no stall horn, no stick shaker).
That’s impossible IRL if there are no serious malfunctions.

1 Like

I normally use the MSFS 2020 default values. That is 50% fuel and 26.3% payload. The “total takeoff weight” is 772364 lbs. MTOW is 987000 lbs.

Well, the real world stall speeds are very hard or impossible to set in MSFS 2020. I think we agree that Asobo flight model “floating” is just another word for “holy cr_ap, the real airplane is no longer in the air at such a slow speed”

Icing :innocent:

2 Likes

… or problems with the sensors. See Final cockpit moments with blocked pitot sensors

The Birgenair Flight 301 - Wikipedia accident: "The investigation concluded that one of the three pitot tubes, used to measure airspeed, was blocked. "

The Aeroperú Flight 603 - Wikipedia accident: “Later investigation into the accident revealed that adhesive tape had been accidentally left over some or all of the static ports (on the underside of the fuselage) after the aircraft was cleaned, eventually leading to the crash”

edited my above post to include the obvious :wink:

I was seriously joking :wink:

1 Like

The MSFS flight model is just Mickey Mouse in the current form, thats all…

2 Likes

It wasn’t myself that made them, he said he wrote a program to analyse the data and then input it into a graph.

Yes it looks like that this is the delay added to give a feeling that replicates inertia.

Odd that they would link stability settings to control surface delay, I would have thought that would relate to dynamic and static stability.

Have you been able to do this? I would like to see what happens

To me it looks like it’s there to overcome underlying issues in either inertia or the effectiveness of controls at varying airspeeds. It would be interesting to know why small control inputs, cause such sudden and large changes in pitch or yaw and also why these sudden changes do not cause the appropriate delay in reaction of the flight path vector to the AoA change. I would expect this instantaneous reaction in a light Extra 330 but not most other aircraft available in the sim.

2 Likes