When configuring aircraft for the past four years, the SDK has given guidance that certain parameters are Legacy FSX parameters to facilitate backwards compatibility. I’m hopeful that MS and Asobo will finally give up backwards compatibility and provide an enhanced, clean slate for moving forward. Developers, including MS partners, routinely use “Legacy” parameters to tweak the Modern flight model. Sadly, though these legacy parameters shouldn’t be required with the modern flight model, many, if excluded from the .cfg file crash the sim.
I certainly hope the New sim engine and dynamic flight model in MSFS 2024 finally “ditch” Legacy FSX and move forward with a clean slate.
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But would that mean many 3rd party models would have to be retired, or modified under Asobo guidance?
Actually, Asobo has said that most 3rd party aircraft should be compatible with 2024 and Devs can adopt the new flight model for their existing aircraft if they choose to (I believe I have that accurate.) So you bring up a good point. If an existing plane will be compatible with 2024 without modification, it seems to follow that the legacy parameters will be carried forward. Perhaps I won’t get my wish. At some point, I feel you have to move forward. It’s been 40 years!
It would be nice to hear Asobo chime in on this.
IF the legacy parameters have to be brought forward to 2024 for compatibility, I would advocate that Asobo PLEASE…
-Not make any Legacy parameter a requirement for making an aircraft perform properly with the new flight model engine.
-Not have a requirement that a Legacy parameter be present in a .CFG file lest the sim crashes.
-Place all the Legacy parameters at the end of the list of parameters under their own category “Legacy” in both the SDK documentation and the Aircraft Manager.
I think this would be an acceptable compromise to allow moving forward if Legacy parameters are required for existing aircraft to port over to 2024.
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Another possibility might be a conversion module/process that would convert legacy parameters to equivalent Modern parameters although I appreciate that might be quite a complex development.
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If the legacy parameters are to be removed, then there needs to be something put in place to allow us to fine-tune specific behaviours which the geometry / core flight model does not get right. This was probably the primary failing of the 2020 flight model - adjusting accurate geometry to incorrect figures to compensate is simply not good enough.
Using the Avro Vulcan as an example - a specific behaviour which is identical during every occurrence is mach tuck. It begins at 0.84M and is consistent. The aircraft has an auto mach trimmer, which gradually repositions the stick so that at 0.96M the stick is fully aft, at which point the only way to stop the tuck is to slow down. The old pitch v mach table was perfect for creating this in FSX, as it was a specific, known, defined and consistent behaviour.
In 2020, whilst it is difficult to define that particular delta accurately, the mach tuck is there. It’s not built in, the core FM does it itself to be fair. However, it begins at 0.96M and it is a sudden nose drop, rather than a gentle tuck. There is nothing to allow me to adjust the speed or strength of the effect.
We need an ability to be specific with known behaviours, to be able to adjust them, not just accept that the core flight model gets it somewhere close.
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Understood. You are completely correct.
I guess what I’m really getting at is this. If the 2024 flight dynamics “natively obtained through aerodynamic simulation of the surfaces defined in the [AIRPLANE_GEOMETRY] section” can’t really provide the effect we need (as described above), give us the tools required to tweak the flight dynamics. Keep the old tools from FSX if that’s needed, but Don’t tell us “This is a legacy FSX parameter not used in the modern flight model.”
Unless Asobo has really accomplished a miracle and put a perfect flight dynamics engine in a $60 piece of software, we’ll need the tools. I’d really just like the “Legacy”, ”Modern” struck from the verbiage and move forward with The Flight Model.
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I’m confused, don’t the legacy parameters in the flight model work when the user has selected to use the Modern Flight Model in the UI?
The request here is to move the Legacy Flight Model choice for users to Developer Mode. People CONSTANTLY turn on Legacy Flight Model in the UI, and then wonder why planes stop flying properly.
The request is NOT to remove the Legacy Flight Model parameters from the various .cfg files.
If I am understanding the issue correctly - the problem is when users select “Legacy Flight Model” and suddenly their Modern Flight Model aircraft start misbehaving.
The solution for that would be to add the “modern_fm_only” option to “true” as described here:
That should solve that issue.
I don’t believe removing legacy flight model from MSFS 2024 would serve any purpose as there are still several aircraft using it plus major devs depending on it.
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Keeping old school format does consume man hours at Asobo just to maintain it and keeping compatibility instead of improving modern flight model. Modern could be perfect if a tiny bit more open regarding impact on compressibility on CL, impact of Reynold on drag and custom slats effects on lift/stall aoa.
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No. Setting “modern_fm_only” doesn’t solve the issue. Developers don’t know it exists and don’t set it. Users CERTAINLY don’t know about the option, and shouldn’t be expected to have to edit planes they purchase. If purchased from the Marketplace they CAN’T set it.
There are no planes available for MSFS that do not use the Modern Flight Model. New users constantly explore the options, see that Legacy Flight model has options and Modern does not, and assume Legacy is better. Then they come to the forums and complain that planes aren’t flying properly. Only to be told that they shouldn’t be using Legacy Flight Model. But, since they didn’t know that LFM is an issue, they don’t say they turned it on. Hours and hours are wasted by so many users it’s not funny. As well as hours and hours of people reading the forums to try to help, only to find out those users, who don’t say they turned on LFM, have turned on Legacy Flight Model. Users who had no idea they shouldn’t set the option. If no normal users are going to use the option, why have it in the main UI?
Legacy Flight model in the UI affects ALL planes once it’s turned on. There is ZERO purpose to having it in the UI. It belongs in the Developer menus. NOT the main UI.
The only people who use the Legacy Flight Model selected in the UI are users who are importing planes from FSX to fool around with them. Sure, developers start with the Legacy Flight Model sometimes because they’re DEVELOPING planes, and it’s what many of them know. So… It belongs in the Developer Menus. Period. Legacy flight model planes still fly properly when Modern Flight Model is selected.
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I don’t have anything in my >500 GiB addons directory that doesn’t set it.
This I can agree with. It should be a flight_model.cfg option only.
Last week, an experienced actual pilot learned if he uses Legacy Flight mode with the A-6, it doesn’t fly as expected. Moderne Flight mode fixed it for him. The AH P-47 specifically says “Don’t use LFM or a kitten will die”. All sorts of planes don’t have the option set. I see people having issues with LFM every week.
Put the option in Developer mode, or make it experimental, with an extreme message that most planes won’t work with it on.
It will never happen, and 2024 won’t be as different as you think it will.
To scrap every piece of FSX code would be to start from scratch. FS2020 showed they are not willing to do that.
I don’ think you understand the request here.
What people want is for the choice to choose between “Modern Flight Model” and “Legacy Flight Model” for users to be modified, so that, if somebody wants to force “Legacy Flight Model” they have to turn on Developer mode. Nobody is asking for the Legacy Flight model, or any other FSX code to be removed from the game.
The issue is that users go in, see that “Legacy Flight Model” has all these options, and they go and turn it on, and then wonder why their planes don’t fly correctly. See the thread for the A-6 Intruder for the latest example. Some guy went on and on how it was having issues, only to find after many posts he didn’t know he shouldn’t use Legacy Flight Model. Really, I don’t know why people don’t know what “Legacy” means.
Saying that Asobo added a “Force Modern Flight Model” option to the aircraft.cfg is not an answer, given that 1. it’s not turned on by default, and 2. apparently very few developers actually know the option exists, and 3. Xbox users can’t modify aircraft.cfg files, and anyone who buys a plane from the Marketplace can’t modify the file, and 4. If people even know they need to do this, they already know they shouldn’t use the option in the first place.
If anything, Asobo should have instead added an option:
allow_legacy_flight_model = 0, with a true value allowing users to change the flight model, and have it default, for all planes, to false and the developer has to actually create and activate the option to allow users to set the Legacy Flight mode option. On top of that, are there features that the Legacy Flight Model mode does that are ignored by the option being set?
The result is, every week we see posts in the forums where people are complaining that their planes don’t fly properly, and they go blaming developers and Asobo and say the sim stinks, only to find out that they had turned on “Legacy Flight Model” and hadn’t said that up front when they complained about the plane. It’s SUPER annoying. And bad for the sim.
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As the OP, my post had nothing to do with the ability to select or unselect Use Legacy Flight Model. Every highly respected developer I work with knows this feature exists.
The point of my post was this:
If Asobo is going to document a parameter as Not used in the Modern Flight Model, then don’t allow the exclusion of said parameter (in the .cfg file) to crash the sim. Furthermore, if Asobo says a parameter is not used in the Modern Flight Model, then a developer should not NEED to use such Legacy parameters to try to get their aircraft to fly appropriately. I would hope issues like these would be cleared up with MSFS 2024.
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Clearly we’re mixing two issues a bit here:
(1) The user options setting “Legacy Flight Model” is no longer needed - it seems the recommendation here is hide that setting from the user somewhat, e.g. move it to the Dev menus. IMHO if “modern_fm_only” is set in the flight_model.cfg then that user setting should have no effect. If it does that’s a bug.
(2) flight_model.cfg with “modern_fm_only” set still needs to include parameters flagged as “unused in the Modern Flight Model” in the doc to avoid crashing the sim. I agree with @GoodOldBird here, my flight_model.cfg files do have the parameters sorted so that all the ‘legacy’ parameters are collected together with a block comment at the top saying “These are legacy parameters not used in this flight model” but it feels odd needing to include them in the file. The Asobo files IIRC just randomly include those parameters scattered through the flight_model.cfg as if the Modern Flight Model is a bit of a bolt-on.
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