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ErichB

Flight Dynamics

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If I were them I would only try to fix a few inherited bugs.

 

Some FDM quirks were actually introduced on the transition from fs9 to fsx. There was some "variable cleaning", and I guess that some additional "optimization" work that caused unwanted effects here and there, and even loss of some interesting features we had in Fs9 and the Combat Flight Simulator series. These account, among other, to loss of some prop effects that were present in fs9, and CFS2 ( never used CFS3 )...

 

It's been a long time since I last dealled with that, so I can't recall exactly the changes that I would suggest...

 

Overall prop ( reciprocating ) engine modeling is limited too. They should at least revisit the leaning bug, and the modelling of variable pitch props.

Jet engines could also get some attention, although the top quality airliner producers have developed their own code for that...


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Avid simmer since 1992...

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Systems modeling is being moved to the 'exterior'... they're trying to make it so you can inject your own engine simulation, as example.


Ed Wilson

Mindstar Aviation
My Playland - I69

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Overall prop ( reciprocating ) engine modeling is limited too. They should at least revisit the leaning bug, and the modelling of variable pitch props.

Jet engines could also get some attention, although the top quality airliner producers have developed their own code for that...

 

Agree  that there are some known flaws with prop pitch issues and the ground friction bug which has always been annoying.  I think the Real Air Dukes (both models) are still affected by the ground friction bug.  I  think they got around the turbo prop engine modelling issues by creating their own model. (i seem to recall reading that in the DukeT manual)

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Agree  that there are some known flaws with prop pitch issues and the ground friction bug which has always been annoying.  I think the Real Air Dukes (both models) are still affected by the ground friction bug.  I  think they got around the turbo prop engine modelling issues by creating their own model. (i seem to recall reading that in the DukeT manual)

 

Yes, but as Ed pointed out above, moving the FDM outside is probably the best option. It will save them a lot of work and dealing with other type of limitations...


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Ryzen 5600x, 32GB RAM, Nvidia RTX 3060 Ti, 1 TB & 500 GB M.2 nvme drives, Win11.

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Avid simmer since 1992...

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Yes, but as Ed pointed out above, moving the FDM outside is probably the best option. It will save them a lot of work and dealing with other type of limitations...

 

Well maybe that's what everyone has been banging on about

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No... unfortunately it's not.


Ed Wilson

Mindstar Aviation
My Playland - I69

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Quote: "Secondly, what is it about the flight dynamics engine which is flawed?  As I understsand it, each aircraft has its own particular FD model.  So if we look at Majestic's Q400 or PMDG's family, or A2A's 172, or Real Air's Duke, we would argue that the 'flight dynamics' are pretty accurate, because the developers made it so. That says to me that the methodology of creating 'the flight model' is unique and specific to each aircraft."

 

It is important to understand that FSX calculates the flight model and it is FSX that determines how the aircraft will move based on the parameters the developer sets in the aircraft.cfg and .air files

 

No developer (except for Majestic as far as I know) creates a flight dynamics model at all. In Majestic's case I believe they turn off the FSX flight dynamics model (which is easy to do via the command FREEZE_LATITUDE_LONGITUDE_TOGGLE) and use their own logic to move the aircraft in FSX.

 

All other developers, when you get right down to it, are essentially using the FSX flight model.

 

The differences are in what settings the developer is providing to the FSX flight model.

 

The aircraft.cfg is mostly concerned with airplane geometry (ie wing size, dihedral, weight, engine type and size etc etc).

 

The .air file largely consists of a bunch of tables (or graphs with an input in the X axis and an output in the  Y axis) which FSX uses to calculate the aircraft behaviour and this is where most of the magic happens.

 

For example, Table 404 is the Coefficient of lift versus Angle of Attack.

 

Want to work an aircraft spin behaviour and its tables 451 (Scalar on Cl beta due to AOA), 456 (Scalar on Clp due to AOA), 460 (Scalar on Cn Beta due to AOA) and 464 (Scalar on Cn r due to AOA).  (One limitation of the FS Flight model I can give you is that each of these tables only permits a maximum of 9 entries which means that the graph is rather coarse).

 

You may also work on table 473 (Pitch moment vs AOA).

 

As for flaws, well one I can tell you is that there is only one wing in FSX. There is no such thing as biplanes as far as the FSX flight model is concerned. The other problem with this is that you can't stall just one wing in FSX (ie the left or right wing).

 

If you are interested in looking at an air file I recommend downloading the Aircraft Airfile Manager V2.2 (it's freeware). With this program you can load any airfile and check out the tables and settings it contains. Most table has a short description explaining what it does. You can get AAM to work with P3D files by simply opening the options and adding the P3D directory to one of the search paths.

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www.antsairplanes.com

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Great info!.  Thanks Anthony

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Will I ever be able to enjoy flying another aircraft in any other sim after a few weeks with the updated F15 in DCS/flaming cliffs 1.28!?

B)

 

Nothing even remotely close to that i P3D!


Haze.

Sweden.

Hotas Warthog. MFG Crosswind. MSFS. DCS. IL-2 Sturmovik: Great Battles.

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No developer (except for Majestic as far as I know) creates a flight dynamics model at all. In Majestic's case I believe they turn off the FSX flight dynamics model (which is easy to do via the command FREEZE_LATITUDE_LONGITUDE_TOGGLE) and use their own logic to move the aircraft in FSX.

 

 

 

So if the tools are there, why aren't more developers doing this?

 

As far as i recall in my early days of simming, the big beef that most flightsim purists had with MSFS was the flight dynamics 'modelling' or engine  - and if I recall correctly, this is where X-Plane found its niche.  Most of them went off to use XP for that reason. 

 

So does anyone know what MS did differently with 'Microsoft Flight'?  The people who used flight said it 'felt better' from a flying persoective and was 'more convincing' as a flight simulator.

Will I ever be able to enjoy flying another aircraft in any other sim after a few weeks with the updated F15 in DCS/flaming cliffs 1.28!?

B)

 

Nothing even remotely close to that i P3D!

 

 

Why?

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Why?

I really don´t know...

I´m not a pilot. I will probably never ever get close to a real F 15. :wacko:

But once in a while I get the feeling that it´s very real.

A feeling of traveling through air... Not moving in a computer game!

 

Orbx/Rex/A2A/P3D high over Alaska, dogfighing with the Spitfire in Cliffs of Dover, Colimatas MIG 29 in X plane and  the F 15 i DCS.

 

The other end of the scale is landing any aircraft in Prepar3d (on those absolutely flat runways)


Haze.

Sweden.

Hotas Warthog. MFG Crosswind. MSFS. DCS. IL-2 Sturmovik: Great Battles.

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So does anyone know what MS did differently with 'Microsoft Flight'? 

 

At least one thing that I was able to notice while examining the CABs of the RV6 - additional cross moments of inertia...

 

This is what I am still able to remember - it's been more than 2 yrs ...  Unfortunately MS FLIGHT inherited from FSX the bugs in the prop model, including the wrong modeling of CS props, the leaning bug, etc...


Main Simulation Rig:

Ryzen 5600x, 32GB RAM, Nvidia RTX 3060 Ti, 1 TB & 500 GB M.2 nvme drives, Win11.

Glider pilot since October 1980...

Avid simmer since 1992...

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If the flight dynamics were to be improved where would the improved aerodynamic data come from?

 

Such data simply wouldn't be available for arcraft designed the the pre-computer age. Only the fundamental data was estimated by the design team and then the test pilots got the flight dynamics right by trial-and-error. The flight dynamics characteristics weren't calculated retrospectively

 

In the post-computer age, The aircraft manufactures use sophisticated CFD modelling techniques together with far better simualations than entusiasts here.  The manufacturers wouldn't provide their data to anyone who asked for it.  

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And.... BTW ( :-) there's also that great tool you can use with FSX, and probably P3Dv2 too... Air Wrench!

 

http://www.mudpond.org/AirWrench_info.htm

 

I have used it myself some years ago to fine-tune some of my preferred GAs for FS9 and then FSX.


Main Simulation Rig:

Ryzen 5600x, 32GB RAM, Nvidia RTX 3060 Ti, 1 TB & 500 GB M.2 nvme drives, Win11.

Glider pilot since October 1980...

Avid simmer since 1992...

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Careful... AirWrench is not an .air file editor. Let us not misinform people.


Ed Wilson

Mindstar Aviation
My Playland - I69

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