1 minute ago, blingthinger said:

Ahh, my bad. I will admit to tuning out a few words when you so graciously declared you were "educating me" (by repeating the same errors over and over again)! But your magnanimous benevolence shan't distract us from the real issue at hand:

Which one is it? Swept wing as in the force element pic? Or straight wing as in the text/equations? Which one is the lie? Given that the writeup came from a well-oiled corporate machine such as M$/Asobo, I hesitate to cast it aside as a typo. Especially after all these years. It's a simple fix, no? Why keep a blatant and egregious aerodynamic error in an important document like that?

It's probably in your best interest try to stick to the points at hand here rather than ironically complaining about repeated errors when you insist on doing misread after misread, and various other "claims" that fall flat on their face.

The diagram on the right is a planform wing model, the left diagram is a trapezoidal wing hypothesis. Note also the sentence on top of those two diagrams, read it even more slowly this time: "The projection of the wing of the plane on the plane is called the wing planform. A typical planform is sketched below:"... Now continue to read further on, it should be quite clear they are using the planform model with various constants/scalars which factor into the calculations to represent a trapezoidal swept wing in the 2D plane using the MAC representation that accounts for sweep angle among various other factors. Yet again you are failing to point out exactly how MS/Asobo are lying here or have a "blatant and egregious" error in the SDK docs, sorry. When making such serious claims, burden of proof is on you, and nebulous statements as per above ain't gonna cut it sorry.
 

5 minutes ago, lwt1971 said:

it should be quite clear they are using the planform model

See! You can learn too! We agree here and repeating (for your learning) what I said earlier: given the amount of time it has been out and given it does NOT actually represent the wings (kind of important for flight) modeled in the sim, this pic is a lie:

Edited November 8, 20223 yr by blingthinger

3 hours ago, blingthinger said:

See! You can learn too! We agree here and repeating (for your learning) what I said earlier: given the amount of time it has been out and given it does NOT actually represent what is modeled in the sim, this pic is a lie:

Sorry no, still not convincing us of this lie nonsense, though I must commend you on trying so hard to push this silly narrative. Again try to learn something here if you can, the current SDK docs clearly state the use of the planform model which results in the 2D representation and simulating of swept wings, so the docs *do* represent what is actually modeled in the sim (as one would expect... otherwise there'd be uproar from various aircraft devs wouldn't you think, especially if they too thought MS/Asobo are "lying"). Now you're back to stating this pic above is a lie which it's not (after failing to show how the current SDK docs has lies), and also it's not in the current SDK docs... stop flailing about lol.
 

Edited November 8, 20223 yr by lwt1971

12 hours ago, blingthinger said:

This is funny. In this case, it was the M$S$ fan that wanted to talk competition.

I didn't state otherwise. 

As an aside, the admins have been very patient here, and you've ignored two polite requests by them to take this to PM's. 

You're going to get this thread closed. Perhaps that's your intent...

7 hours ago, WestAir said:

I didn't state otherwise. 

As an aside, the admins have been very patient here, and you've ignored two polite requests by them to take this to PM's. 

You're going to get this thread closed. Perhaps that's your intent...

Naw. The admins are worried about bringing XP into the discussion. I'm not at fault there. In fact, I keep avoiding that one. Maybe they also didn't like the discussion about proper technical English, but I've avoided that one too.

I keep bringing it back to CFD. There's also a side note about misinformation spread by the SDK. Even slander! But clearly there's a 'lost in translation' aspect in that discussion.

If this thread gets shut down, it won't be my fault.

 

8 hours ago, lwt1971 said:

the current SDK docs clearly state the use of the planform model

Exactly. The planform model is the straight, hershey bar wing config. This is what both the force-coefficient-element and CFD models are using.

CFD of the wrong geometry (straight, hershey bar wings in place for a swept wing) is inherently going to lead to incorrect results.

13 hours ago, blingthinger said:

See! You can learn too!

Austin? Is that you?

9 minutes ago, Bdub22 said:

Austin? Is that you?

Ha! I wish I had that level of mustache!

4 hours ago, blingthinger said:

Exactly. The planform model is the straight, hershey bar wing config. This is what both the force-coefficient-element and CFD models are using.

CFD of the wrong geometry (straight, hershey bar wings in place for a swept wing) is inherently going to lead to incorrect results.

I can tell you are absolutely unbiased  passionate truth finder who absolutely unaffiliated with X$lane LOL 

Swept-back wing aerodynamics, and finite vs infinite wing modelling has a LOT to do with the way some interesting aerodynamic effects are modelled.

It makes quite a difference at transonic speeds, and airliners cruising at high speeds benefit a lot from it, not to mention supersonic aircraft...

In a correctly modeled swept-back wing, which btw  is presently not the case in XP12:

- CL in a swept-back wing is proportional to the cosine of the sweep angle;

- while for the purpose of drag calculations the direct relative wind (full forward speed) is taken into consideration, this for an infinite wing model. Induced drag should be invariant to the sweep angle, so, both a straight and a swept back wing should produce the same values, given both have a similar spanwise lift distribuiton, and hence induced drag... Adjustments can be made to adapt for more realistic finite wing models. (*)

I couldn't find in the MFS documents any mention to how correctly this is being modeled in MFS. Most parameters listed in the configuration files and which were used in the Legacy model are now signaled as not used when the modern "CFD" model is active, so, those that we could use to fine tune the effects of sweep are gone, and I wonder how it's calculated now.

Guys, regarding some of your posts above, I really - REALLY - can't picture Austin playing hide&seek at a forum... He his too honest&practical&direct&inteligent&busy to spend his time on such childish tasks... He is, though, always ready to answer an email, sometimes in 5 min ! at weekend, sundays and holidays included !  Unfortunately I have no way to reach ASOBO this effectively & fast to make them aware of inconsistencies in MFS and promptly receive feedback !!! And... it has been like this since I interact with Austin, and not some new mood caused by competition...

(*) @Murmur and @Alec have made a detailled description of this for LR - Murmur is our Encyclopedia  for Aerodynamics stufff !!! - in order for it to be fixed in future versions of XP. Would be nice to hear from ASOBO how the modern FM copes with it...

Edited November 9, 20223 yr by jcomm

17 hours ago, blingthinger said:

M$

It doesn't matter how many different combinations you use with the letter "M" and the symbol "$", it always will come across silly and lazy. Yes, Microsoft is a company. And yes! You guessed it! Most companies want to make money. It's not an outlandish concept to grasp, but yet -- here you are: mix and matching the M's and $'s into varying elaborate instances...M$F$ ? Really? It's embarrassing. I've had to squint reading things you've written. They're cringey at best. Yikes. 

2 hours ago, Bdub22 said:

It doesn't matter how many different combinations you use with the letter "M" and the symbol "$", it always will come across silly and lazy. Yes, Microsoft is a company. And yes! You guessed it! Most companies want to make money. It's not an outlandish concept to grasp, but yet -- here you are: mix and matching the M's and $'s into varying elaborate instances...M$F$ ? Really? It's embarrassing. I've had to squint reading things you've written. They're cringey at best. Yikes. 

Yeah, this sort of desperate, keyboard warrior stuff is just one huge yawn.

not sure what you guys want to know about CFD, this topic is so long that it is impossible for me to follow it hahahaha

 

Best,

S.

6 hours ago, jcomm said:

Swept-back wing aerodynamics, and finite vs infinite wing modelling has a LOT to do with the way some interesting aerodynamic effects are modelled.

It's a huge deal! Dutch roll is a big part of swept wing aero. Hence the need for yaw dampers! I can't imagine the hoops PMDG is jumping through to get where they are now. Oh, the inane gymnastics!

 

6 hours ago, jcomm said:

Most parameters listed in the configuration files and which were used in the Legacy model are now signaled as not used when the modern "CFD" model is active

This isn't entirely accurate. The CFD model is actually not the 'advanced flight model' that they reference in that parameter table. That's a reference to the force element model.

A lot of those legacy parameters would still be useful today given that the underlying model is still FSX. Many devs have complained about their effective removal. There are still a couple Mach #-based terms that can be adjusted, but nothing that would account for the lack of roll-yaw coupling effects.

That said, the use of the term "force element" is also false advertising. Per the SDK, the elements aren't actually calculating forces. They are merely scaling force coefficients. Very different concepts with very different outcomes. But, it is a reasonably effective way of putting springs under that FSX rocking chair. 

Edited November 9, 20223 yr by blingthinger

1 hour ago, simbol said:

not sure what you guys want to know about CFD, this topic is so long that it is impossible for me to follow it hahahaha

Hey great to see you on here Simbol.. ya lol this thread is rather long winded, but just wanted to know your general thoughts on using CFD in the aircraft flight model of your Sting S4, and if there were specific advantages/disadvantages to using CFD vs not, etc. My initial thoughts are is that it's another tool in the MSFS aerodynamics toolbox, but given the current inability in the SDK to define aircraft geometry in fine-grained ways, the CFD tech in MSFS for aircraft FMs can't likely be fully utilized with ease... Obviously great flight models can be developed in MSFS without CFD given the various 3rd party aircraft examples out there, but wondering if you had specific motivation(s) to employ CFD for the S4. Broad questions I know but if you have the time we'd love to hear 🙂
 

Edited November 9, 20223 yr by lwt1971