For those playing at home, the Airbus crosswind recommended technique is the wing down method as shown by @anon50268670 in these couple of vids.
I see you’re both (from what I’ve read) also actively flying on the A320 too, so this should be interesting… Granted it seems I’ve skipped over the best juicy bits. Where’s that popcorn gone?
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It does during flare? Its quite a bit higher over the threshold indeed.
Yes it was never the intend of this test to fly according procedures (neither do I know them).
Yeah it is impossible to fly a stable approach in MSFS under these conditions. On the other hand 60 to 80 kts of wind that low above the ground is also extreme so the actual problem might be having to select such extreme winds in order to end up with half of that over the runway. But this was without any doubt an unstable approach.
I guess so, I’m flying the Embraer 190/195 and ATR. There still is a lack of inertia in my opinion, you can probably give us a better insight. Just doesn’t feel there is any mass to it.
Well, enough to get fatherly on you!
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Do you fly the TBM or similar like a PC12 IRL @Yeti64? If so, awesome, thanks for that input.
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If you’re starting from scratch…
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I made a video. See https://youtu.be/7_sJiSS00BA
I wrote as video comment:
How does MSFS 2020 version 1.14.5.0 simulate crosswind approach and landing? This is an interesting question on MSFS 2020 forum. See More Physics, More Real Winds - #721 by AromaticGenie50
I fly Frankfurt airport runway 25C approach with 16015 (160 degree, 15 kts strength) wind, no gusts a C172 with my flight model mod. That is exactly 15 kts crosswind.
This video confirms my expectations: In the air, there is no realistic simulation. I fly the approach “hands off”. You see a nose “yaw” because of the crosswind, but the airplane still flies a straight line WITHOUT PILOT INPUT. At the moment the wheels touch ground I get realistic simulation - you see how the airplane moves as I try to counter the cross winds effects.
For me this is the same as in take-off: you get “left turning tendencies” as long as the wheels touch the ground, but the “left turning tendencies” immediatly stop after lift off.
Summary: MSFS 2020 has a realistic “on ground” simulation, but a non-realistic “in air” simulation.
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Guys, by no means something you can take reliable conclusions from, its just speculation but maybe your thoughts? Regarding the lack of inertia, I decided to compare the A320 in a hard-over rudder scenario against a video I’ve seen on the internet concerning a Boeing 737. I know different aircraft etc. just watch this:
From minute 12:15 (time stamp is wrong):
Default A32N (can’t turn off flight computers on the FBW one with custom FBW, so I took the default A32N), at MTOW (as much inertia as possible), flight computers OFF. First time without pulling back, second attempt with pulling back:
The rudder hard-over itself doesn’t look far of from the video, little too responsive on the rudder if you ask me. The elevator effectiveness is too low in my opinion. The barrel roll at the end using full rudder and aileron is a bit less realistic though.
Yes the rudder is very, very twitchy for some reason, that is what I meant with there is no inertia. Every gust of wind or control input immediately affects the flight path. Although my rudder hard-over test does not look too unrealistic…
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Assumption 3. MSFS2020 has a “1000 surfaces” airplane model, but this is still not enough for realistic simulation
I vote for Assumption 3. Asobo themself write in SDK documentation file:///C:/MSFS%20SDK/Documentation/03-Content_Configuration/SimObjects/00-Aircraft/Flight_Model.html#complex-physical-phenomena-modelization
“Asobo people and experimented pilots collaborating with Asobo have noticed poor behaviors for limit cases, typically when approaching stall which has motivated the team to put some additional efforts on physical modelling of « limit » flight configurations, which are notoriously badly represented in the classical aerodynamics theory underlying FSX historical flight model.
The introduction of 3D geometrical information in the flight model through surface elements, as described in the previous paragraph, was clearly a first mandatory step toward improving the physics, as it has enabled the modelization of local phenomena. To better account for stall and all its variants (spin stall, deep stall, simple stall), each surface element has been enriched with a float parameter describing its level of stall. When reaching a certain level of stall, the behavior of the surface is changed using additional parameters so as to follow, broadly speaking, the behavior of a falling plate.”
Asobo speaks of a “first mandatory step toward improving the physics”. And yes, after the first step many more steps are necessary to go the full distance.
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There is “real” inertia in MSFS 2020 with the empty_weight_pitch_moi, … parameters. And there is “fake” inertia with the pitch_stability, … parameters. Maybe the CORRECT mixture of real and fake inertia gives the best simulation MSFS 2020 can do.
At the moment I reduce fake inertia to a minimum - like Asobo themself advise, but not do in their cfg files.
Do you have the Manoevering speed for the Airbus for me and the limit loadfactor? I mean the VA and not the flap maneuvering speeds. Maybe we can see if it stall before reaching the limit loadfactor, that might be an objective test of inertia and elevator effectiveness. Only thing I can find on the internet is this, but it doesn’t mention what weight:
I have been experimenting with the simulator’s FDM using a more mathematical approach and I’ve noticed a few things - MSFS flight model might not be as bad as it seems.
Reading the SDK documentation, this is how I think MSFS flight model works:
FSX and other table-based simulators use data tables for global aerodynamic coefficients (Cl vs AoA, Cd vs AoA, Cm vs AoA), which determines the behavior of an entire aircraft. As these coefficients are empirically accurate, the aircraft’s flight performance can be accurately reproduced. However, local aerodynamic effects like induced yaw, induced roll due to rudder input, stalls etc. can not be reproduced accurately, as they depend on geometrical properties of an aircraft.
MSFS works by dividing aircraft into several surface elements, giving each surface element its own set of local aerodynamic coefficients, then integrating element forces to determine aircraft behavior. But how exactly are these local aerodynamic coefficients determined, given that they don’t have empirical data unlike global aerodynamic coefficients? This is where MSFS normalization algorithm comes into play.
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. 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 and other moment related tables seem to be significantly off - maybe this is the reason MSFS aircraft feels twitchy / inertialess: unlike other local aerodynamic coefficients, moment related ones have a significantly less accurate fit. I hope Asobo addresses this and allows for a more complex fit with more data points.
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I’m not so sure about the flight model anymore, I’ve used the A32NX development version, flight computers off to do design maneuvering speed test. I have found the table below on the internet, although not knowing for which exact A320 model and for what weight those speeds are.
Idea is to fly 250 kts at FL100 and pull the sidestick full back, the g-loading can be seen on the bottom of the lower ECAM display and should peak at 2.5g before stalling.
At MTOW: peak g-load = 1.9g
At 59.8t: peak g-loading = 2.4g
At 43.5t: peak g-loading = 2.8g
In none of the situations does the aircraft exceed critical Angle of Attack and reach accelerated stall with side stick full back.
The elevator authority is seriously limited, it suffers from the same issue as the Cessna 172 and a lot of other aircraft, that is, even with the stick full back you can’t force the aircraft into a stall. When trying an accelerated stall during a steep turn you can’t physically maintain altitude until stall, with the stick full back the aircraft starts descending. It seems impossible to force exceed the AOA on the wings, I’ve seen in one of the aerodynamic videos they made “improvements” on tail stall characteristics, maybe they over did it a little bit. And being able to loop a fully loaded A320, also not very plausible.
If this isn’t something straight out of GTA V then I don’t know anymore.
What do you guys think?
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I have the impression that the fight model is potentially great, but that it is not configured properly. They apparently did tune the model to match data from the POH for example, but such documents do not contain quantitative data about adverse yaw for example. It is also in these areas that a lot of problems with the flight model are observed by IRL pilots.
If only they would do a single aircraft in full detail, for example the C152, and make it perfect. Just as a showcase of what can be accomplished. That would be awesome, wouldn’t it?
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I hope that is what they are doing with the 172, like the other flight Sims though it’s all about Third Party Add-ons which will make this sim great
Looking at the wind, I’ve just run some tests with the A320NX in Developer build. Take off and then climb circling the airport to cruise level.
With ‘live’ 
weather and wind at 27107, the wind reported on the ND every 2000 ft up to cruise was fairly linear, starting at 7 on the runway and then ending up at 41 at 37000ft.
So I reset, changed the ground wind layer to 27120G30KT (with 5 gusts per minute), and did it again.
Reset again, and did it with 27130G45KT.
The main thing I noticed was that the gusts were there being displayed in the ND with corresponding movement of the aircraft all over the shop, and this was all the way up to cruising altitude. Between 21-29 kts for the first one and 32-45 kts for the second. I’ll come back to this in a second and make a thought re inertia.
Now I’m no meteorologist and the weather is a complex old beasty, but obviously wind gusts are in part caused by surface friction of the earth and other factors. The surface/planetary boundary layer of the atmosphere is the one nearest to earth, and where this takes place. It’s height changes based on a number of factors but it is not infinite, and has a cap.
I’ve read various heights mentioned dependent on conditions from just off ground level to 2-3000 metres. So say 10,000 feet as a maximum for the purpose of this.
Above the planetary boundary layer is ‘free atmosphere’, where the effects of surface friction are negligible, so it stands to reason that the gusts would disappear by then, if not before. So why are the gusts still there at 35000ft, and why does the strength of them remain constant from 1000 feet all the way to the top? Unless I’ve got something fundamentally wrong of course.
Onto inertia. When you setup wind with gusts and take off, notice how the wind speed changes in the ND. When a gust kicks in, the speed bounces back and forth rapidly between the actual wind speed, and the gust speed. In the 27130G45KT flight I did, it was rapidly and randomly showing on the ND between 32 and 45 knots. And by rapidly, I mean around 5 times a second. Sometimes it jumps straight from 45 to 32, then back to the 40’s, into the 30’s , then back up to 45 and so on. Then we have some calm as the gust subsides, then it’s rinse and repeat
So if the aircraft in the sim is responding to the effects of the rapidly changing wind speeds the weather model is creating, and that wind is ping ponging back and forth every 0.2 seconds, is that what is causing some of the excessive roll and yaw back and forth we’re seeing as the weather model keeps shifting the goalposts and the plane is simply reacting to the information it’s getting thrown at it?
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As a GA Pilot since 1982 and a Sim Pilot for only 3 months I find this thread quite daunting. Maybe some people are having a bit of a peeing contest?? For around $100 I think its a marvellous program and will only get better over time. Perhaps Sim Pilots have unrealistic expectations at this early stage of development?? It reminds me very much of Windows. In the early days it used to drive me nuts. Now Windows 10 is a very stable platform.
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Exactly! That is the problem. If you want to simulate 30 kts gusting 40 kts you’ll need to punch in 60 gusting 80, which is nonsense. Above the friction layer it is normally less turbulent and gusty as those gusts are mostly produced by obstacles within the friction layer. What they should have done is work it the other way around. Take the ground wind you punch in, and modify it to simulate the wind above the friction layer and fade out the gusts. Also the 50% of the geostrophic wind thing at ground level might work fine for light to moderate winds, for strong winds I’m not so sure. Landing in 25 gusting 35 kts the wind isn’t 70 kts at 1000 ft, no way!
Might be, still in the real world there is quite some mass going down that flightpath, so rapidly changing winds especially when its pinging back and forward will probably not have any effect on the net flight path. In MSFS it doesn’t feel like there is any mass behind anything.
I’m complaining about this since day 1. It’s the typical RC plane behavior. I wonder why it is so hard to fix. It’s almost impossible to avoid a twitchy take-off roll.
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