X-Plane Technology Preview One

[mjrhealth 820]

13 hours ago, jarmstro said:

Ah! I see. Sorry for the blasphemy. Didn't mean to offend..😀

I dont know hiw you could offend anyone.

[mjrhealth 820]

4 hours ago, Murmur said:

Well, that topic was very funny to read. I chuckled at many replies: "MSFS is better because it uses 1000 surfaces instead of 10", "MSFS uses a panel method", "MSFS flight model is light years ahead"... None of which is true.

On the other hand, it's specular to those people that say that XP is necessarily better just because it uses BET, or just because it's used to predict the flight model of hypothetical aircraft.

One thing said in that thread was correct though, i.e. the fact that XP flight model has had decades of improvements, whereas MSFS is less than a year old, so it has a lot of room for improvement. Although, I'm not really convinced that the approach they've taken for the MSFS flight model is the right one. From how it is described in the SDK, seems like it's a bit of a mess.

I think MSFS flight model manifests itself as the result of the work of a physicist with no experience in aerodynamics, whereas I think it should have been designed by an aerodynamicist.

Now on the other hand, it's true that no flight model is perfect, and XP itself has only recently (i.e. months) improved in several lacking aspects, and it still has flaws. A 100% comprehensive flight model would require too much resources (both human and hardware), in particular in aspects like aeroelasticity, supersonic, post stall, etc.

Anyway, I don't have any flight sim installed right now due to lack of interest. Not necessarily because of said flight model limitations, but mostly because of a general lost of interest in virtual things.

Keeps my brain functioning, more fun than brain numbing u tube

[Janov 2,383]

The one big difference between BET and MSFS approach is that BET can "predict" an unknown designs aerodynamic behaviour, while MSFS model can only mimick "known" aerodynamic behaviour - which is totally fine for existing aircraft - or even making a not existing aircraft where the intended behaviour is known.

BET is likely to be less accurate over the whole envelope, because it is not "scripted" but makes simplified assumptions. Its like playing Civilization to find out who would win the second world war (after setting up the scenario as closely as possible), as opposed to watching a documentary about it.

Another point that Jcomm critized: Pitching moment due to flap deployment can per definitionem not be calculated by the BET model of X-Plane. Aerodynamic properties of airfoils are "predetermined" in the airfoil file, X-Plane is not using fluid computation to determine lift, drag or pitching moment. Therefore a change in airfoil properties (like flap deployment is) can not be "calculated" but must be predetermined by the designer.

In both cases, the outcome hinges to a large part on the skill of the actual aircraft designer. In both cases you can´t simply enter real aircraft numbers and expect the result to fly "by the book" - and you need access to real performance values and behaviour parameters that even long-time pilots on the type can usually not provide.

Edited June 7, 2021 by Janov

[Humpty 751]

7 hours ago, Janov said:

There are folks whose judgement about a flightmodel I would trust. Others I wouldn´t.

jozeh aka Jcomm" . ofc for gliders mostly and props. 

[Murmur 3,941]

46 minutes ago, Janov said:

The one big difference between BET and MSFS approach is that BET can "predict" an unknown designs aerodynamic behaviour, while MSFS model can only mimick "known" aerodynamic behaviour

Well, the so-called modern FM in MSFS should be a predictive FM (just like XP), but the problem is that right now it's much less accurate, and more difficult to tweak.

[Janov 2,383]

48 minutes ago, HumptyDumpty said:

jozeh aka Jcomm" . ofc for gliders mostly and props. 

I know - but if someone calls the flightmodel for gliders "rubbish" - I start having doubts about that persons expertise.

I have flown mostly airliners for the last 25 years, my time in props is only like 300 hours and a long time ago. My actual stick time in gliders and helicopters is "a few minutes". I would not consider myself current enough to really judge a props flightmodel, but I think I can tell if it is believable or rubbish.

Jcomm (aka the "uninstaller") is known for a very special desire for fidelity in certain features that he deems "conditio sine qua non" or absolutely essential for the enjoyment of a flightsimulator. He gets excited about the implementation (or lack of) some esoteric aerodynamic effect...finds out that the simulator he so loved a few minutes ago doesn´t exactly get it right - then uninstalls the simulator in a wave of hyperbole and disappointment and (although I haven´t heard him say it) - proclaims the flightmodel to be "rubbish".

While being a genuinly likable (and always ready to laugh about his "uninstalling disorder") character, I would not cite him as the ultimate judge of a flightmodel. As others have said before, we need to be able to accept some compromise, not get frustrated because some vortex generator creates 3% less drag than it does in the real aircraft. Otherwise you can never enjoy flightsimulation...and will end up uninstalling them in frustration 😉

Edited June 7, 2021 by Janov

[Humpty 751]

1 hour ago, Janov said:

I know - but if someone calls the flightmodel for gliders "rubbish" - I start having doubts about that persons expertise.

I have flown mostly airliners for the last 25 years, my time in props is only like 300 hours and a long time ago. My actual stick time in gliders and helicopters is "a few minutes". I would not consider myself current enough to really judge a props flightmodel, but I think I can tell if it is believable or rubbish.

Jcomm (aka the "uninstaller") is known for a very special desire for fidelity in certain features that he deems "conditio sine qua non" or absolutely essential for the enjoyment of a flightsimulator. He gets excited about the implementation (or lack of) some esoteric aerodynamic effect...finds out that the simulator he so loved a few minutes ago doesn´t exactly get it right - then uninstalls the simulator in a wave of hyperbole and disappointment and (although I haven´t heard him say it) - proclaims the flightmodel to be "rubbish".

While being a genuinly likable (and always ready to laugh about his "uninstalling disorder") character, I would not cite him as the ultimate judge of a flightmodel. As others have said before, we need to be able to accept some compromise, not get frustrated because some vortex generator creates 3% less drag than it does in the real aircraft. Otherwise you can never enjoy flightsimulation...and will end up uninstalling them in frustration 😉

Lol "Uninstalling disorder"

Yeah true that he can't be the ultimate judge , but saying it because of his real world experience that's what I go by, . 

He is has been my teacher for the dynamics and Wx. 🙂 not that i understand most of it ehehehheeh

 

Edited June 7, 2021 by HumptyDumpty

[mjrhealth 820]

I could sit here and complain about what  i dont like, but I got it for flying and when im flying to busy doing pilot stuff to care about scenery, but than Im old and not so fussy. Im happy when I get given something nice.Dont have time to whine.... lifes to short, but than some maybe dont have a life.

[jcomm 5,919]

Well,

I didn't write that "rubbish" word in this thread, and honestly pretty much like Murmur, I am so away from using a flight simulator ( not from flight simulation as a theme which is still of special interest to me, just like aviation, aerodynamics, ... ) that I really can't load any of the sims and go for a ride and explain, more in detail, what I find needs attention from their developers, being it ASOBO, LR, LM, whatever...

Some limitations, and gliders are indeed a great tool to test some of the most fundamental aerodynamic characteristics depicted my a modelled aircraft, are far from being nitpicky.

Actually, my posts in this thread, if you care to check, are mostly about, first the enthusiasm about ephemeris being finally implemented into X-Plane, and looking fwd for the next version, then some posts ahead trying to express why I really don't think users should be using this threads to debate the "sex of the angels" regarding which sim is better, aka "mine is bigger than yours" mindset that unfortunately plagues most XY-based inhabitants of Earth ( and that's probably why we see so few women around here... they're surely a lot more objective... )

So Janov, you really don't need to bring that "feature" of mine to the table - it's no longer an issue - I have uninstalled them all 🤣

 

Edited June 7, 2021 by jcomm

[Humpty 751]

13 minutes ago, jcomm said:

 

So Janov, you really don't need to bring that "feature" of mine to the table - it's no longer an issue - I have uninstalled them all 🤣

 

🤣

[mSparks 2,086]

20 minutes ago, jcomm said:

trying to express why I really don't think users should be using this threads to debate the "sex of the angels" regarding which sim is better, aka "mine is bigger than yours"

personally, i'd be very happy with certain people not posting things like

5 hours ago, Greazer said:

It does not consider air flows over or between terrain, for instance up and down and around mountains.

4 or 5 posts after a video showing it considering the air flows over terrain and up and down mountains.

23 minutes ago, jcomm said:

gliders are indeed a great tool to test some of the most fundamental aerodynamic characteristics depicted

very true..... There are also a lot of people with real glider experience who can compare to the real world and feedback, which is why I assume certain sims avoided them completely lest such comparisons actually got made.

[Janov 2,383]

1 hour ago, jcomm said:

So Janov, you really don't need to bring that "feature" of mine to the table - it's no longer an issue - I have uninstalled them all 🤣

😂

Even Aerowinx?? I thought that was finally a sim that got it right! 😉

(...and still trying to figure out how your signature fits in with what you wrote 😁)

Edited June 7, 2021 by Janov

[jcomm 5,919]

1 hour ago, Janov said:

😂

Even Aerowinx?? I thought that was finally a sim that got it right! 😉

(...and still trying to figure out how your signature fits in with what you wrote 😁)

Aerowinx is by far the BEST, but it's so complex and niche that these days I can't find time to play it ...

Sig. is like when you say to your girlfriend: "yes dear, I was at work last night - it's being stressful these days my love..."

[mSparks 2,086]

39 minutes ago, jcomm said:

"yes dear, I was at work last night - it's being stressful these days my love..."

Last time I wrote something like that my old girlfriend read it.

[Janov 2,383]

You guys are lucky, I can´t even have a girlfriend (my wife won´t allow it! 😂)