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

So… by this it would also seem to imply that I could drive the road course at Laguna Seca in a fully laden Chevy Suburban, and then drive the same course in a Mazda Miata and get the same result?

Faulty thinking my lad.

We are not discussing an atmospheric model here; we are discussing a flight model unique to each aircraft.

I never said such a thing. I didn’t say all planes have the exact same behavior. I said physics apply to all planes the same. Inertia works the same in a Chevy Suburban as it does in a Mazda Miata. So does friction. So does torque. So does drag.

On your part.

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For example, take a 1m² section of aerofoil, say, part of a rudder.
At an IAS of x, angle of attack of x etc it will produce a certain resultant force as calculated by the flight model. The above variables (and likely many more) can then be changed depending on the aircraft type to determine a particular aircrafts handling characteristics, the underlying method of calculating of force will remain the same.

Couldn’t have said it better :+1:

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On this image, we can see how bugged the flight model is.

According to the weight debug window, the CG is in forward of the CP, yet in the pitch overlay, it appears aft of it.

Even more disturbing is the negative AOA of the horizontal stab producing an upward lift, verified by both the pitch overlay and the vectors from the Sim Forces debug overlay.

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I return to my original statement: there is no one-size-fits-all flight model.

Now if you want to talk about fluid dynamics, or vibration theory, or differential equations - all elements of aeronautical engineering - I’d be happy to chat.

I’m late :sweat_smile:

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Maybe it’s because i’m not reading that info properly, but it looks to me like the horizontal stabilizer has a positive AOA. The plane mockup shows it with a positive AOA. And seems to me like “Elevator incidence” is relative to the plane horizontal reference, so 3.6-1.4 = 2.2 degrees positive AOA.

We are apparently talking about different things and/or are having different expectations.

This has always been something that I’ve found difficult to grasp. If the sim models the real-world, then I’d have expected that you would just need to tell the sim the physical characteristics of your plane, and it would fly. Give it the size and shape of the flying surfaces, the mass, the engine profile, etc. and leave the rest up to the sim.

Perhaps giving that information to the sim is what is referred to as creating the flight model. But if that’s the case, then why isn’t it just a case of seeking out the real-world specifications of the aircraft in question, and feeding those into the sim?

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Almost a 1000 views and only 70 likes, not much people interested in flight model improvements it seems :sweat_smile:

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Thank you for your input but unfortunately, you’re wrong.

Elevator incidence is a bad translation to English. In French incidence is angle of attack. So elevator incidence is elevator angle of attack, which is measured in reference to the relative wind direction.

How do I know? I’m a frenchman, so all the little translation errors make sense to me lol.

EDIT: but I agree with you, the pitch overlay makes little sense. Seeing how the horizontal stab is positioned, the elevator AoA should be reading close to 0°, not -1.4°. By the way, this makes me think that it could be possible that they calculate the AoA of the wing and the elevator differently.

EDIT 2: another example of wrong elevator AoA calculation

:joy::joy::joy: Perfect. So what is angle of incidence translated then?

Angle de calage :wink:

From wikipedia in French: " Attention, angle of incidence (en) en anglais correspond en français à l’angle de calage, l’angle formé par la corde de référence d’une aile et l’axe de référence de l’avion."

Another proof that there is a problem with swept wings: I’ve set the sweep angle to 0° and… the CG and CP are correctly located, with the CG forward of the CP, and the elevator producing a downforce to counteract the pitch down moment created.

No changes in mass or balance were done: mass is 200 tons and CG is located at 20%MAC.

Thats an interesting find! I already suspected something like that, thanks for confirming!

I don’t think so, and your screenshot proves it. At -9.4 degrees AoA i’d expect the elevator to be pointing down in the diagram, but it’s pretty much level. This indicates to me that the elevator angle is relative to the plane. Not only that, but it’s not generating any lift at all in any direction, which is what i would expect for -9.4 degrees of AoA.
Either way, i’m not going to push the point further.

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I don’t know how to interpret that data, but could it have something to do with variable incidence horizontal stabilizer? In normal (trimmed) flight the elevator deflection is indeed 0 with no corresponding force created by the elevator itself as it is faired with the stabilizer.

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Same test with FBW A320, mass of 41 tons, CG 20% MAC.

With the sweep:

Without the sweep:

With the C172: mass 767 kg, CG 20%MAC

With default 1° sweep:

With 30° sweep:

I’ve included AP debug window showing the elevator deflection.