Most airplanes are doing good when the developer implemented CFD+NPS correctly, maybe Nemeth Designs did a good job there.
They increased the adverse yaw a little bit, that should be noticeable while rolling in/out of a turn (when you use the ailerons) and yes it has a low aspect ratio, so the adverse yaw shouldnât be very strong anyway.
Overall adverse yaw is not that much noticeable because of MSFS limitations.
The aileron drag coeficients only apply if you really roll with aileron, which is not the case during the entire turn.
fuselage lateral cx is the main factor. but you really need to set it out of the default range to see an effect. Try the above values in any aircrat and you will see a BIG YAW during turns. Just copy them into the AERODYNAMIC section, if they dont exist already.
and rudder_lift_coef seems to have an impact on how much rudder you need, to counter the yaw.
Very interesting, thanks for sharing your findings!
Gonna take a look at the values.
I found a very good short video explaining all the important points.
While turning/rolling left or right:
the aileron that moves up causing the wing to produce less lift
the aileron that moves down causing the wing to produce more lift
The wing that produces more lift, is also creating more drag.
Thatâs inducting the adverse yaw
(at the beginning and the end of a turn, where you are mostly using the ailerons both in a opposite position).
And then comes your finding into play: the fuselage.
ââwhen the airplane slips sideways through the air, the wind hitting the side of the fuselage
creates extra dragââ which means more/ continuous adverse yaw. Boom
Maybe Iâm misreading your post, but Iâve never heard of a sideslip being described as adverse yaw. Adverse yaw is a transient effect of both roll rate and aileron useage thatâs countered by coordinated use of the rudder. Once the roll is stopped and the ailerons are neutral, then any remaining slip doesnât create adverse yaw, itâs just a slip. Itâll actually tend to weathervane the nose into the relative wind (the essence of a turn), but centrifugal force and the horizontal component of lift are out of balance (the nose is lagging the turn).
That said, adverse yaw can briefly cause a sideslip, but itâs not used to describe the continuous condition of a slip or caused by a slip.
However, if your airplane has strong dihedral (stability that wants to return it to wings level) or wants to overbank in certain turns, then you have to keep aileron in throughout the the turn, which will cause adverse yaw while theyâre deflected.
I shouldnât use ââcontinuous adverse yawââ for sideslip, sorry for that
Iâm adding this from another forum:
The act of rolling the aircraft creates adverse yaw, which generates sideslip. This is a transient effect which is explained here:
There are three sources of adverse yaw:
Difference in induced-drag due to ailerons: down wing aileron reduces lift while the up wing aileron increases lift, which generates a difference in induced drag in each wing. This yaw moment counters the desired yaw motion.
Yaw-roll damping: as roll rate builds up to steady-state, the down wing experiences a larger flow incidence while the up wing experiences a smaller flow incidence due to the rolling motion. This is a twisted-lift concept: because of the difference in the local AOA, the lift and drag vectors are twisted. At steady-state roll, the total lift on each wing is equal, so the yaw moment really comes from the twist.
Converted sideslip: if there is a non-zero AOA, the rolling motion will convert some of the AOA into sideslip; this sideslip is opposite to the direction of the turn. This effect is especially pronounced when the roll rate is large. Some high performance FBW systems will address this by implementing stability-axis roll instead of body-axis roll, especially on fighter jets whose roll rates are high.
When youâre experimenting, donât forget to take into account that in a single-engine airplane, a lot less left rudder is needed rolling into a left turn than right rudder is needed rolling into a right turn.
Default is 0.4 - which is about the perpendicular drag of a cylinder - and the value should usually fall between 0.2 and 0.8 for most aircraft.
usually between 0.2 and 0.8⊠Now comes the funny partâŠ
I checked the MSFS ââgolden standard planeââ Cessna 172 G1000,
because there I wanted to begin with the testâŠ
Then I saw the value:
fuselage_lateral_cx = 4.3
freaking 4.3 !!! And they suggest 0.2 - 0.8 for the developer!
I checked a few community and other MSFS base airplanes
and they are all using these low values around 0.4âŠ
No wonder we have weird aerodynamic bahvior everywhere,
because with low fuselage values like this, the fuselage doesnât exist in MSFS
Fuselage CX has a default value of 4.0 and should ideally fall between the range of 0.2 and 0.8. This value helps give more YAW stability (ie: how easily the aircraft will return to center).
Fuselage Lateral CX: Defines the perpendicular drag coefficient of the fuselage, which occurs when the airflow is going perpendicular to the front axis (ie: sideways - left to right or right to left) but also going up and down. This coefficient has an impact on drag when side slipping, as well as a general impact on yaw stability and pitch stability. The default value is 0.4 - which is about the perpendicular drag of a cylinder - and the value should usually fall between 0.2 and 0.8 for most aircraft.
so which is it? is Asobo confused themselves?
and would you say the 172 G1000 is realistic there?
in other words, would for such a plane a 4.0 factor be more like the default, than 0.4 in your opinion?
Fuselage CX has a default value of 4.0 and should ideally fall between the range of 0.2 and 0.8. This value helps give more YAW stability (ie: how easily the aircraft will return to center).
Yes that even confirms itâs an typo all over!
the point of the value is simply in the wrong place,
it should be: 2.0 - 8.0
instead of: 0.2 - 0.8
then the suggested default value of 4.0 would also make much more sense.
It also matches with the Cessna 172 G1000âŠ
if this airplane has 4.3 and is relatively small,
then a big aircraft canât have 0.4 unless itâs an
RC-Airplane !
And as @JayDee6281 pointed out correctly, this number is counteracted by rudder_lift_coef /
how much rudder you need, to counter the yaw.
If rudder_lift_coef default is 5 (which makes sense, when you use it for a big stable aircraft) and you use this in combination with a small fuselage value of 0.4 you create a completely twitchy aircraft unless you use a very small Rudder Effectiveness value to counteract this, but itâs still gonna result in a twitchy mess, exactly what we currently have.
Typically, barring other settings, setting fuselage_lateral_cx higher than about 1 will make a plane an absolute rock in a forward or side slip. Iâve found that 0.8 is a nice starting point for most planes but Iâll increase it to 1 for things with a lot of fuselage side area and up to 1.4 for things that are very draggy in a slip (such as the AN-2 on floats). Combine a properly-set fuselage_cx with the newer crosswind/wheel friction numbers also set properly (and proper control response, elasticity, inertia, etc) and you get something wonderful. FWIW the G1000 172 does NOT have those new crosswind/friction numbers in place.
Also, re: adverse yaw and this thread in general, things that Iâve changed in various planes that do, in fact, have an impact on it include things like aileron_up_limit, aileron_down_limit, wing_camber, aileron_area vs aileron_span_outboard, etc.
To say the sim doesnât support adverse yaw outside of âcustomâ coding is completely false.
Iâm all for realism and making planes fly like real planes (as thatâs what all of my mods strive for) but the easy out is to blame Asobo when the blame is firmly on the devs either being unwilling or unable to use the numbers correctly.
Nobody said that, mostly there is no realistic adverse yaw behaviour outside of custom coding, if itâs achieveable is another question, we are just looking at the results.
So it looks like some values are off and developers are using the wrong values and creating their flightmodel around it/ compensating the wrong values.
Thatâs also just a guess, we need Asobo to clarify if they did something wrong with the Fuselage CX default value and range suggestion. But so far itâs looking like this is the case.
Thatâs why I opened the bug report thread.
FWIW I just gave a quick test drive to the 172 with its 4.3 fuselage cx and, as predicted, it drops like a rock in a slip. I can get 2400 fpm clean and 3100 fpm dirty which is grossly exaggerated. For comparison, the real life Porter in inflight beta with full flap will descend at 4000 fpm. The 172s Iâve got hundreds of IRL hours in might hit 1500-1800 fpm with full flap in a slip but certainly nowhere near 3000+.
Ha. If you quickly add/remove rudder in the G1000 172 you can quickly lose/gain 20-30 knots of speed like a yoyo.
For sake of argument, if 0.4 is incorrect, and really should be 4.0, then you find that other aspects of the simulation are wrong, that could just be that those other values already mentioned are wrong as they are built around 0.4 being the value for âfuselage_lateral_cxâ.
I do wonder though if that value is changed, and you then adjust the others to compensate, you may end up back where you started with regard to how the simulation is expressed.
The other values define how ââeaselyââ you can counteract the fuselage airflow effects,
how effective the rudder and ailerons are and what effect do they have and lots of other stuff.
However, what they donât affect is the general airflow drag on the fuselage:
when the airflow is going perpendicular to the front axis (left to right, right to left, up and down)
sidedrag when slipping
yaw & pitch stability
This is defined by the fuselage_cx. And thatâs whatâs missing with all these aircraft, they feel like they donât create any drag by the fuselage and itâs no wonder if the number is way too low in general, thanks to typo suggestions.
The wind creates drag on the fuselage when hitting it from different directions.
But appart from that, even with no wind, as soon as you use the ailerons and you create adverse yaw, it also increases the drag on the fuselage, causing a slip (in uncoordinated flight).
This is why Iâm suspect of messing with the fuselage values. All these things work in concert and there may very well be more values we havenât discovered or simply a lack of some interactions that donât allow granular control of this particular variable.
But if you still have it tweaked, try doing a sideslip (wing-down) crosswind landing. Iâm betting with it tweaked, the drag will be way more than is present irl. And thatâs a no-go for me.
