17 minutes ago, SAS443 said:

You must not speak of this again

Awww word not allowed! I broke the first rule of Fight Flight Club.

I'm not sure real has any tangible meaning until you are looking at motion platforms, accurate yoke/tiller/throttle components with proper resistance and force feedback, etc. Any student pilot will tell you the Cessna Yoke reacts to the inflight (or on ground) forces. I can make the yoke move on the ground with the throttle lever. One inch of movement on the ground is an entirely different amount of effort than one inch of movement in the air.

Even with a 1:1 simulation of an airframe, you're not gonna get anywhere near realistic behavior with a $50 joystick and some rudder pedals.

I've been waiting for superior sim for years FS, FSX, P3D, XP11 and so on. LOL 

Philosophically speaking any sim no matter it's been marketed predominately have of entertaining value with some little training on the side !   Yes I welcome extra realism, but why should stop kidding yourself. We can't buy an  airplane for $100 in real life then why do we expect for the same value  software that imitate flight 1x1 to RL. So lets take simulation with grain of salt., they approach real world only to some degree. They useful if we know how to use them smart yet they still represent  pure entertainment.

As I told already before  no CFI will enrouse a student who had thousands of hours in super realistic sims and zero actual dual.

 In conclusion without I tell you what MSFS is the only sim in the world where I can find my house! And it look like 5 years ago but still I LOVE IT!

3 hours ago, Cai Zicheng said:

Controls engineer here. The first requirement of a control algorithm test bed is that you have accurate dynamics to tune and test it on. Otherwise the control algorithms you built will be VERY off when deployed on real vehicles.

So if NASA says they are using X-Plane as control algo test bed, then it's a huge stamp of approval for X-Plane flight dynamics then anything else.

and they do.. but they are not using X-Plane.. they are using X-Plane pro which carries a license fee of $750 ( or a USB key version for $820) and opens up things in the SDK that are just not available to normal users or the global flight model..  Cylinder and Spherical projection, for example, are only available in the professional version.. it also then allows you to use that software in a professional setting simulator (many tens of thousands of $) so you can actually start to get close to a certfiable source...   this is NOT what you get in X-Plane global which is what 99% of people actually use. 🙂

 

Graham

10 minutes ago, sd_flyer said:

 In conclusion without I tell you what MSFS is the only sim in the world where I can find my house! And it look like 5 years ago but still I LOVE IT!

This is indeed a gorgeous feature of MSFS2020, and I'm not ashamed to say that I fly over my house nearly everyday, that I often visit places that mean a lot to me, and being able to actually fly my little 172 over them is meaningful, at least to me. Yes, this is something I had been waiting for.

A.

5 minutes ago, Moria15 said:

and they do.. but they are not using X-Plane.. they are using X-Plane pro which carries a license fee of $750 ( or a USB key version for $820) and opens up things in the SDK that are just not available to normal users or the global flight model..  Cylinder and Spherical projection, for example, are only available in the professional version.. it also then allows you to use that software in a professional setting simulator (many tens of thousands of $) so you can actually start to get close to a certfiable source...   this is NOT what you get in X-Plane global which is what 99% of people actually use. 🙂

 

Graham

Is the flight model different in the Pro version?

A.

3 minutes ago, ADamiani said:

Is the flight model different in the Pro version?

A.

well they state in their documentation that there are different plane configurations and flight models in the pro version so I would assume yes 🙂    Also they stated that in an email enquiry I sent a couple of yesrs ago about this.

G

Edited March 28, 20215 yr by Moria15

8 minutes ago, ADamiani said:

This is indeed a gorgeous feature of MSFS2020, and I'm not ashamed to say that I fly over my house nearly everyday, that I often visit places that mean a lot to me, and being able to actually fly my little 172 over them is meaningful, at least to me. Yes, this is something I had been waiting for.

A.

So here is my philosophy. MSFS is not perfect so is P3D so is XP11. Yes  I want all sim to improve, but MSFS is the most beautiful for sure! LOL It's like a joke about a guy who dating three girls: the first one smart money saver, the second  was good house keeper, and third one was great cook. Guys struggled with his choice but in the end married one with biggest boobs! 🙂

Just now, sd_flyer said:

So here is my philosophy. MSFS is not perfect so is P3D so is XP11. Yes  I want all sim to improve, but MSFS is the most beautiful for sure! LOL It's like a joke about a guy who dating three girls: the first one smart money saver, the second  was good house keeper, and third one was great cook. Guys struggled with his choice but in the end married one with biggest boobs! 🙂

Oh I thought there was a fourth girl ..... I may be getting old but I still remember a few things 😎

4 hours ago, BiologicalNanobot said:

MSFS' normalization algorithm has a single task - finding the correct set of local aerodynamic coefficients which will match global aerodynamic coefficients in all flight conditions. In order to accomplish this, MSFS starts by distributing global aerodynamic coefficients to surface elements proportional to their surface area. After that, an iterative optimization algorithm will further tune local aerodynamic coefficients so that when all element forces are integrated (when a “zero-order” solution is reached) resulting global aerodynamic coefficients will match the global aerodynamic coefficients entered in tables. I am not sure why they try to estimate local aerodynamic coefficients for wings though, as they are already available in the form of airfoils, which is what X-Plane uses. I assume this is for backwards compatibility purposes, so that FSX tables still can be used the same way as before.

I did lots of experiments and it looks like MSFS almost perfectly matches Cl vs AoA and Cd vs AoA tables for almost all flight conditions. However, Cm vs AoA tables and other moment & stability related data seem to be rather off - maybe this is the reason MSFS aircraft feels twitchy / inertialess: Unlike other local aerodynamic coefficients, Cm and other moment related coefficients have a worse fit. I hope Asobo addresses this and allows for a more complex fit with more data points. Several days ago I've noticed someone else reporting the exact same thing - local Cl and Cd fitting the aircraft really well while Cm having a worse fit, so I think this is reproducible too.

A straight wing vs a swept wing vs a delta wing will have different spanwise distribution of lift.  Different fuselage and engine mount configurations will also have different local coefficients around them.  Yet the normalization algorithm is "one size fits all", mapping every aircraft to the same idealized geometry with only a handful of parameters to adjust that geometry.  It also doesn't allow for things like a true biplane flight model.

It may be an interesting way to try to have some local effects like stall, etc derive "naturally" from the flight model while maintaining backward compatibility with the FSX tables, but I'm very skeptical of the results thus far. 

Edited March 28, 20215 yr by marsman2020

4 minutes ago, marsman2020 said:

A straight wing vs a swept wing vs a delta wing will have different spanwise distribution of lift.  Different fuselage and engine mount configurations will also have different local coefficients around them.  Yet the normalization algorithm is "one size fits all", mapping every aircraft to the same idealized geometry with only a handful of parameters to adjust that geometry.  It also doesn't allow for things like a true biplane flight model.

Some geometrical information is better than none, which is the case in FSX/P3D. What matters most is if end result matches global coefficients, which seems to be the case for Cl and Cd and less so for Cm (and other stability related ones)

Otherwise P3D wouldn't allow a true biplane flight model either.

Edited March 28, 20215 yr by BiologicalNanobot

Anyway, regarding the flight model, we have two choices.

1) Look at numbers, formulas, drawings, whistles and bells, and conclude that with all that effort the model MUST be right. Same approach as those engineers that assume they can tell you if an amplifier sounds good or bad just looking at the numbers. Maybe even worse than that, because not even I, as a professional mathematician, would be able to do that. I understand the formulas, I know physics, I am not afraid to study a problem in depth; but all I would be able to say is that what I see is formally right or wrong. That it actually reproduces the actual behavior within a given approximation is another story, This is the first lesson for my students when I introduce mathematical modeling in my courses.

2) Ask a real pilot to give it a try and judge if what they see is close enough to reality. Of course, we have to factor out of the equation all the motion stuff, which means a lot. This is the same as inviting a musician to my house, asking him/her to listen to their own songs through my stereo set and say whether it sounds the way they meant it*.

The only simulator that is very, very close to reality according to real, type-rated pilots (all of those who have tried it), is Aerowinx PSX. Disclaimer: I am not Hardy Heinlein, PSX author. I just admire his work.

*when I actually did that, this friend of mine said that my stereo set sounds wonderful, but also said that, first of all, he could hear some subtleties that they hadn't actually thought about during production, so they were there more or less by chance. Second, that audiophiles like me look for things like purity of the sound, dynamics, depth, quickness, that are not top of the list for professional musicians, who are more worried about armony, rhythm, voice impact, pitch, punch and others. After all, they have to sell their music, right? So is what we listen to "real"? Probably not, under the point of view of the musician who actually wrote, sang and produce that song 🙂.

A.

29 minutes ago, Moria15 said:

well they state in their documentation that there are different plane configurations and flight models in the pro version so I would assume yes 🙂    Also they stated that in an email enquiry I sent a couple of yesrs ago about this.

G

Flight model is the same, difference is projection and other unlocks for hardware like real garmin units.

Also performance checks, vulkan was really needed.

My dad is better than your dad.

15 minutes ago, CaptainNick said:

My dad is better than your dad.

My sim is clearly superior to yours.