FS2004

[Leen de Jager]

Bonjour amis,
Excusez moi pour placer le texte anglais.
J`ai trouvé cette article sur AVSIM.

Il y a un nouveaux future pour FLY ????


Amities
Leen



Hello All,

Yesterday I directed people in this forum to a really important thread over on the developer's forum, regarding the changes just being discovered in the way MS2004 handles the simulation of flight dynamics. These talented people have looked beyond the new eye candy at the heart of how FS2004 works, and have found some very disturbing things.

The thread seems to be coming to a conclusion, and its not a good one for anyone who thinks FS is more than a game. I've pasted the text of the main concluding post below, it is a long read but well worth the effort. I also recommend reading the entire thread, which can be found at this link:

http://forums.avsim.net/dcboard.php?az= ... c_id=12256

Essentially, MS2004 does not take into account certain very important variables of flight dynamics that 2002 did, so aircraft in 2004 have taken a big step backward in terms of realistically simulating flight. Moreover, unless a workaround is discovered, Microsoft has eliminated the ability of aftermarket developers to create accurate flight models- and those which are so wonderful in 2002 will perform markedly worse in 2004.

So you may not want to bother loading up that Dreamfleet Archer or Carenado 210, all the hard work that went into making them such good planes goes to waste when they're placed into the constraints of 2004. And for those of us who have commented about how "well" these planes fly in 2004, seems to be quite the opposite.

Anyway, draw yourown conclusioons from the following but I am very upset to find that all we've gained in 2004 is eye candy, at the unecessary expense of accurate flight modeling. Here's the post word for word:

______________________________________________

Thanks to all of you for re-testing and to all others who have contributed.

I believe we have all reached the same conclusion now with everyone eventually confirming my finding that both incidence and twist, together with their pitch and drag consequentials, default to zero at all times in FS2004.

After giving this some thought I now conclude that this is not a mistake. It looks more like a a design time decision. I find it unlikely that the different variables relating to incidence and twist could go missing from the different equations in the flight model unless someone was instructed to go through the code and remove them everywhere they occur. Someone has. If this was an error some of the variables would still be working.

Since the terms often get confused let me explain that FS2002 had an excellent flight model but dreadful default flight dynamics. The flight model is in the binary code of the product and is used by every aircraft. The flight dynamics belong to a particular aircraft and are coded in each aircraft.cfg and air file. The people who wrote the original flight model for Microsoft understood aerodynamics. The people who wrote their flight dynamics did not.

Since there was nothing significantly wrong with the flight model and it had the capability to support realistic flight dynamics some of us who understand real world flight dynamics set about writing flight dynamics files for MSFS which exploited the capabilities of the flight model better than the proprietary default flight dynamics. By the middle of this year tens of thousands of Microsoft customers were downloading our work for free and enjoying the additional realism which we were able to unlock. Increasingly consumers were also buying payware aircraft because they were obviously superior to the aircraft delivered by Microsoft.

What those who have contributed to this thread have just proved is that Microsoft have degraded the internal flight model equations just enough to ensure that realistic flight dynamics will no longer work in FS2004. We have been very careful to test with their SDK compliant default aircraft and at full realism.

By carefully altering their proprietary code Microsoft have ensured that their commercial competitors, however small and insignificant, can no longer deliver products which are superior to their own. Some of you will have noticed for instance that Rob Young has posted elsewhere that Microsoft have removed the ability of the SF260 to spin in FS2004, whilst enabling spin within the Extra and Jenny FDE.

This is entirely consistent with US law and entirely in accordance with the long term competition strategy of Microsoft as a corporation. Microsoft are perfectly entitled to react to competition by altering their proprietary code in ways which disadvantage others and make Microsoft look good.

Opportunity, motive and modus operandi? You decide.

The destruction of the pitch attitude and drag equations within the internal flight model stands in stark contrast to the impression which Microsoft conveyed prior to the release of FS2004.

We have just proved that FS2004 is not compatible with any existing aircraft flight dynamics, even when they were fully compliant with all Microsoft SDKs. Destruction of the realistic pitch equation has ensured that FS2004 displays such aircraft at fake nose up pitch angles which preclude an appropriate view over the panel or VC. By removing the ability to process the drag correction from air file Section 1101-50h Microsoft have ensured that such aircraft suffer degraded performance in FS2004 because they always have excess drag. They become visually and dynamically incompatible with FS2004.

FS2004 does not have an FDE converter. It just ignores key aerodynamic data from earlier SDK compliant FDE, degrading them so that they are no better than the new default FDE. Third party aircraft produced by experienced FDE authors, whether freeware or payware, always had significantly more realistic flight dynamics than MS default aircraft and are therefore degraded more. The Microsoft default FDE were so unrealistic that removal of the chosen aerodynamic variables from the flight model has hardly changed their attributes. I believe this points to careful selection and beta testing of the variables removed from the flight model equations.

The implications for payware publishers whose expertise lay in producing realistic aircraft which exploited the internal flight model to the full are obviously grave, but they are not the only ones who suffer.

The vast majority of MSFS consumers could never tell that the default aircraft had faulty flight dynamics and are therefore no worse off. The minority who could tell, including aviation practitioners and those who have invested hundreds of hours using the product to learn how to operate aircraft realistically from scratch, have been slapped in the face. The equations in question did not have to be destroyed for the eye candy aspects of FS2004 to work. Microsoft could have ensured that your favourite FS2002 freeware aircraft and your collections of FS2002 payware aircraft continued to work in FS2004, just by doing nothing at all to the flight model. Instead they made changes which ensure that all your FS2002 aircraft are degraded.

We have proved that Microsoft have removed key aerodynamic variables from the flight model equations.

Accident or design? You decide.

Now I need to address a 'what if' that have come up in this thread suggesting that there is an FDE work around which can overcome removal of the variables.

Ron, Bob and Douglas are talking about how substituting variation of AoA for AoI still 'works' and will have to be employed instead. Whilst this could restore realistic pitch it cannot restore realistic drag and will make the drag result even worse.

Since Microsoft have ensured that FS2004 cannot process the drag data correction from Section 1101-50h the result of using an AoA rotation to substitute for an AoI rotation is a cartoon rotation which produces the wrong induced drag and a very distorted performance envelope. The drag consequences of +4dAoA and +4dAoI are very different.

Picture a wing meeting the air and the bottom of the fuselage meeting the air in an aircraft where incidence = 4 and AoA = 4. The fuselage is level (aircraft has zero pitch) but the wing is four degrees nose up and is inducing substantial drag at 4dAOA. In FS2002 we could code the pitch and the drag for that aircraft differently and correctly.

Now if we use an AoA rotation to remove the incorrect value of zero AoI which Microsoft have imposed for all aircraft in FS2004 we must make the wing have zero AoA to show the fuselage level again (zero aircraft pitch). Having reduced the AoA by 4 degrees to force the fuselage to zero pitch there is now also zero angle of attack and zero induced drag, producing a huge drag error.

The proposal that AoA rotation substitute for AoI rotation ignores the fact that we have just proved that Microsoft have destroyed the drag equation as well as the pitch equation. The induced drag error cannot be corrected even though the pitch error can be corrected by the means proposed.

This thread was never about data loading and reloading bugs in FS2004 real as they seem to be for some people. This is about the extent to which FS2004 is still a flight simulator at all.

An FDE author can force FS2004 to display aircraft at the correct pitch but not with realistic drag. In FS2004 there is still a link between AoA and drag, but Microsoft have destroyed the link between pitch and drag. To make an MDL 'fly' at the right visual pitch it now has to be 'animated' like a cartoon. The MDLs are no longer 'flying' because in FS2004 as we have just proved they are not following the laws of flight.

The consequence is that those who choose to produce FS2004 aircraft and updates will have to invoke a solution which is part video game and part flight simulator. Part cartoon animation and part dynamics code. The implications of this internal code change extend far beyond the world of FDE authors. Would be FS2004 MDL authors and painters of quality products have not understood yet. flight dynamics authors will have to explain it to them.

When an aircraft is produced for use in any flight simulator, not just this one, the net flight incidence component of the flight dynamics equations is used by the FDE author to rotate the MDL to allow for wing incidence after it has been produced by the MDL maker. This FDE code also controls what can be seen over the panel or VC at run time. The FDE author then corrects any consequential drag error separately.

That the FDE author can no longer do any of this in FS2004 is what this thread proved.

For use in a video game which lacks wing incidence as a flight dynamic variable the MDLs have to be produced with their incidence rotation built in by the MDL maker at design time. We have just proved that the incidence variable is absent in FS2004.

Let that sink in now and get ready to explain it to your project collaborators.

That is what I mean by a *serious* bug in FS2004. The other new bugs are inconsequential by comparison.

If producers have the goal of releasing FS2004 aircraft with even somewhat realistic performance envelopes which also fly at the correct displayed pitch attitude the only solution is as follows.

1) MDLs have to be rotated nose down by the net incidence of the real aircraft at design time to display correctly.

2) The MDL animations have to be prepared to match that nose down rotation.

3) The textures also have to be rotated nose down in the paint package.

4) The FDE then have to be prepared with an 'overstiff' nose oleo which 'corrects' the nose down sit of the rotated MDL on the runway. Mainwheel oleos of tailwheel aircraft may be stiff enough already. I have tested and this works well.

5) The MDL oleo animation may have to be written accordingly and not accurately.

6) The rest of the FDE then have to be written to match an 'equivalent aircraft' of zero incidence and zero twist but retaining the real world lift slope and consequential induced drag. Drag errors can then be 'somewhat corrected' using other data fields in Section 1101 which FS2004 can still process.

If AoA rotations are used in lieu of the MDL rotation, as some have proposed, there is no way to correct the induced drag, (consider the zero case to understand why), and FS2004 is just a video game with animated cartoon aircraft. That seems to be the way this product is developing and I acknowledge that the majority of consumers who only use the product as virtual airport spectators and virtual passengers will be quite happy with that.

The compromise above will therefore satisfy most FS2004 users, including most payware customers, but it is still a compromise with less accurate flight dynamics than FS2002. The comprise is largest for the fastest aircraft. Consequently I doubt that FDE authors whose expertise lies in creating realistic flight models will choose to spend hundreds of hours over the next couple of years producing or updating 'compromised' FDE for FS2004. They may decide to write payware FDE for FS2004 if the price is right, but their more demanding customers will always expect more realism than we now know is possible in FS2004.

Those who have promised to produce FS2004 updates have a larger problem. Rotating pre existing MDLs is simple enough, but rotating all the animations and all the textures of a pre existing MDL may not be at all simple. It depends on the package used to create the aircraft originally. The FDE have to be rewritten anyway. All the other new FS2004 bugs also have to be taken on board and if possible fixed. The most important of these are the CoG bugs. Since I think I have now decoded them I will try to explain them later in a different thread.

If anyone wants to design a Whitley for use in FS2004 the only choice will be an MDL rotated at design time, but I expect that most FS2004 third party aircraft will be displayed at fake pitch angles within the video game and most users will not notice. However since the fake pitch angles are always nose high you cannot obtain the correct view over the panel and you will wind up having to cheat in various ways to see where you are going, by scrolling the panel, or using a video game zoom factor, or some other video game cheat, to control the game. This has never been a requirement when flying with realistic flight dynamics.

Due to removal of the incidence and twist variables the VIEW_FORWARD_DIR and SIZE_Y variables within panel.cfg, cannot always be used solve the view on approach problem in FS2004 in cockpit view due to ground / air mismatches previously solved by FDE code. There are no equivalents for the VC anyway. Setting the correct view over the VC 'panel' has to be resolved by MDL rotation in FS2004.

All of which leads to my position on updating my own 'realistic' FS2002 freeware flight dynamics.

My finding that FS2004 is unable to process three key aerodynamic variables essential to realistic flight simulation has now been confirmed by a range of experts. It is therefore not a question of how long it would take to produce FDE updates. FDE which are realistic in FS2002 cannot be updated to be realistic in FS2004. It cannot process the variables and equations which would allow real world inputs from flight manuals to cause the real world outputs. I cannot update my FDE for realistic first person flight simulation use in FS2004. The necessary code has been removed by Microsoft.

Of course if the key variables were removed by mistake all Microsoft have to do is restore the old equations. They know where to find them.

FSAviator



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[Azzurro]

Effectivement, c'est assez sidérant de lire cela, c'est d'ailleurs le genre d'évènement qui se produit lorsqu'un industriel est en position de monopole, il peut à tout moment changer les règles et le public n'a qu'à suivre, bon gré mal gré.
De la part de MS, qui pratique le "ne vous en faites pas, je pense pour vous, et je sais ce qui est bon pour vous", ce n'est pas étonnant en fait.

Donc oui, oui, oui, mon cher Leen, tu as raison, c'est une chance de plus pour Fly!, qui offre aux vrais amateurs la possibilité de dépasser le stade du jeu pour se rapprocher du monde réel !
Amitiés

[Leen de Jager]

Merci Jean-Paul

Amitiés

Leen

[Robert51]

Il faut dire que les gens ne sont pas raisonnables comme disait le très regretté Coluche : "Il suffirait que les gens n'achétent pas pour que ça se vende pas ".

C'est bien la confirmation que vu par PetitLogiciel, la simulation n'est qu'un jeu à vendre en masse pour que quiconque se prenne pour un pilote sans mal : "Appuyez sur E pour démarrer, plein gaz et décollez. Le merveilleux monde des plus lourds que l'air vous appartient !".

Emballez avec de la pub, du marketing, donc quelques millions de dollars et voilà le résultat. Comme le disait Coluche "il voudrait qu'on soit intelligent et il nous prennent pour des c...".

Mais attention, la commission européenne vient de faire les gros yeux à Billou. On va voir ce qu'on va voir....rien au final je parie.

Savez-vous qu'un membre de la commission d'enquête sur PetitLogiciel a pris une année sabbatique....chez PetitLogiciel (pour s'occuper des roses sans doute). Qui a protesté, vilipendé cette attitude ? Personne. Ca manque décidemment de rebelle dans ce bas monde !

Idée saugrenue: TRI ne serait-il pas disposé à mettre l'exécutable de Fly! I ou II (pas les sources)en freeware Entre pas de vente et le donner ça aurait au moins l'avantage d'enquiquiner un peu PetitLogiciel.

(NdM: pour ceux qui comme moi n'ont pas compris tout de suite, PetitLogiciel est la traduction mot à mot de ... non quand même, je ne le dirai pas!)

[Azzurro]

pour ceux qui comme moi n'ont pas compris tout de suite, PetitLogiciel est la traduction mot à mot de ... non quand même, je ne le dirai pas!)

Je trouve que "petit" est un peu... gros comme terme traduit, c'est plus infinitésimal que ça, c'est minus-scopique en fait
Quant au second terme, je l'avais traduit par "chiottes" un jour, et j'avais mérité les réprimandes d'un lecteur... c'est vrai que des chiottes infinitésimales ne seraient pas bien utiles, alors que la Firme en question est indispensable à la marche du monde... hélas !
Volez bien quand même, attention aux orages dans le sud !

[guesnel]

c'est comme pour l'OS il l'a appelé " windows" , pour qu'on puisse jeter l'argent par sa fenetre !

bon la je crois que je vais avoir droit aux réprimandes des modérateurs
mais j'aime ça !

c'est comme l'histoire du maso et du sado :

" bas moi !....... NON ! NON !! "

[Robert51]

Tu te souviens de leur pub télé ? "Jusqu'où irez-vous ?" .
Ma réponse : Jusqu'à le jeter par la ...fenêtre !

Encore une bien bonne de la part de nos hystériques yankees. Je viens d'apprendre que les providers "laposte.net" et "ifrance.com" font partie d'une liste noire. De ce fait je ne peux pas correspondre par courriel avec mon oncle qui réside aux USA (nul n'est parfait !). A méditer.

Peut-être pas un coup de M. Facture Porte, faut pas exagérer !