Those aren’t the only two simvars that effect it, but they are a large contributor. The SDK goes into more detail on this.
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Wasn’t aileron up/down drag implemented to make the adverse yaw even work in the first place, because there was non before?
But yeah the wing aspect ratio should play a big role too, gonna search in the SDK if it’s even listed with an affect on adverse yaw.
Wing dihedral is mentioned, I believe.
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I’ve added TA (Total Adverse Yaw)
which represents the summary of in- & decrease of UD & DD,
taking the default values into account and what the increase and decrease means for each value.
Higher TA Number = more Adverse Yaw
It’s funny because of the comment that the JF-Piper Warrior II has good adverse yaw and it actually matches with the number.
The JF-Turbo Arrow IV should have even more adverse yaw, currently the leader of the list (besides the custom codes)
wondering if it would make more sense instead of using the difference of both values to use the ratio, 2.0 being the default?
I used the actual default numbers 0.5 and 1.
If 0.5 is decreased I added that, if it’s increased I substracted that.
If 1 is decreased I substracted it, if it’s increased I added that.
That’s how it affects the adverse yaw according to the SDK and with the total number out of that you can see the if the over all Adverse Yaw was decreased or increased.
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The sum of the two is arbitrary in itself, but an indicator as a single number of how much it was changed. It shouldn’t be used as a reflection of how accurate the adverse yaw is likely to be, only an indicator of how different from default it is.
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They are coefficients, meaning they are multiplied with other variables.
An up_drag_coef of 0.5 and a down_drag_coef of 2.0 have the same effect on the aileron drag differential (->adverse yaw effect) as an up-drag_coef of 0.05 and a down_drag_coef of 0.2
(at least that’s how I read the SDK)
Therefore their ratio, the result of dividing the down_coef through the up_coef, would give a more meaningful indicator of how much a developer deviates from the default 2.0 ratio IMHO.
Two examples:
DG Aviation LS8-18 0.125 0.25
→ 0.25 / 0.125 = 2.0
no change in adverse yaw to the default, despite different, smaller, drag coefficients
SimWork Studios Kodiak 100 0.2 1.89
→ 1.89 / 0.2 = 9.45
large change in drag coefficient ratio (effecting adverse yaw) almost five times over the default of 2.0
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I’m currently not at home, but I’m gonna look into it as soon as I’m back.
But what you said makes sense, thanks for explaining!
On the other hand, as long Asobo doesn‘t implement adverse yaw better in the flight model with more variables (e.g. related to wing roll rate), we should not spend too much effort focusing on the aileron drag differential only. IRL that defines only a fraction of the adverse yaw forces, particularly for planes that are expected to demonstrate strong adverse yaw - planes with high wing aspect ratios. Using aileron drag differentials exclusively to simulate adverse yaw is atm more like a hack, trying to patch over the insufficient modern flight model.
There was a
yaw_moment_delta_aileron
variable in the legacy flight model. But Asobo made the mistake of canceling that, believing the new more granular modeling based on aircraft_geometry would provide adverse yaw naturally. But that didn‘t happen…
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The weird thing is people telling me in the wishlist thread “msfs has all the tools to implement realistic adverse yaw”
Also people coming in here saying certain planes have realistic adverse yaw. Also in the CFD list thread were a few people naming certain airplanes.
But when you look in some development forums they calling the aileron up/down drag implementation a unrealistic workaround.
But you are probably right, for the basic implementation Asobo needs to put more work in it to be called realistic.
It seems to be the best implementation of adverse yaw are the aircraft with own custom codes, using non of the msfs “workarounds”.
I just wanted to add - that the adverse yaw due to aileron drag is only applied as long as you actually roll into your bank angle. Once you established your bank angle for your turn, the ailerons are nearly zerod out. So the yaw moment during a stable turn is not much impacted by the two parameters (aileron_up_drag_coef and aileron_down_drag_coef).
The yaw during a stable turn should come from the native flightmodel according to the sdk. They state it is therefor important to get the airplane geometry right.
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Hey JayDee, thanks for joining, I’m a big fan of your YouTube videos 
and thanks for the explanation!
Is there any example where they got the airplane geometry right / adverse yaw could be called realistic or do you think it’s impossible and there is still a core simulation problem ?
Because if airplane geometry would play any role in msfs, we would have had some sort of Adverse Yaw even before the aileron up/down drag implementation, but there was/is absolutely nothing.
I have yet started recently to look into averse yaw, in the moment I would say it is just flawed. But I think one could work around with the vtail, but I am not there yet. At the moment no aircraft comes to mind, but I remeber that there was a warbird, where it seems like it worked.
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I’m told the Kodiak 100 has some actual adverse yaw.
Also the WB-Sim 172 Classic Enhancement has some.
Or maybe the easiest way would be just substracting DD - UD.
Example:
Default Value: 1 - 0.5 = 0.5
Kodiak: 1.89 - 0.2 = 1.69
Arrow IV: 3.9 - 0.2 = 3.7
Then we have an total Adverse yaw factor starting from 0,
which takes the increase and decrease of each value into account.
Yes completely true, but the sad reality is, those 2 up/down drag values are currently the only ones truly affecting Adverse yaw (but only at turn in and out).
This list does a few things:
- showing which aircraft could have some sort of adverse yaw
- showing developer with custom adverse yaw implementation
- showing that Asobo only implemented an aeromodel ‘‘hack’’ for adverse yaw
- several SDK values doesn’t work as intended (specially airplane geometry)
hoping the community joins in on the wish that more work needs to be done
I’ve changed TA to represent the adverse yaw in total starting from 0,
higher number = more adverse yaw (partially)
Thanks to the feedback and research of the last days I also updated the wishlist topic:
Adverse Yaw - more improvements necessary
Great work and that’s by far the most organized OP I’ve seen on this forum! 
I’m really hoping we see this implemented correctly into the sim one day. There are quite number of fundamental things that do not work correctly with GA-flying right now. More so than any other aircraft category…
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Added:
MrTommymxr:
- DA40-NGX improvement mod
- DA62X improvement mod
Greetings -
latest release (v1.0.2) of Nemeth Designs Partenavia P68B Victor is now featuring Adverse Yaw, the ailerons drag coefficients are set as follows:
aileron_up_drag_coef = 0.5
aileron_down_drag_coef = 2
I cannot attest the effect being noticeable while flying (could be due to the wing having a comparatively low aspect ratio), still IMHO the aircraft overall flight model has been definitely improved with this release.
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