correct as-is F16 Low Speed Adverse Yaw

[777coletrain]

After update 2.7.15.25026 I’ve noticed that the F-16 has a lot more adverse yaw when at slow speeds than it used to. I’m not entirely sure if this is actually something wrong with the flight model but it is very strange having to use the rudder in a fly by wire jet. I’ve held off on this due to the lack of information I have to support this but I figured it would be better to just post here instead of sitting on it.

F16 Rudder 22 6 22.trk

[Carbon715]

Wind perhaps? (Haven't looked at track)

[777coletrain]

16 minutes ago, Carbon715 said:

Wind perhaps?

There is no wind in the mission

Edited June 22, 2022 by 777coletrain

[RuskyV]

Something feels wrong though, roll has almost the same response at any speed and altitude, this includes landing which gives a horrible spring like behaviour with yaw. The instinct is to counter with rudder if you make any course adjustments during final approach, however leaving rudder out you get this weird left to right motion in yaw.
 

Two patches ago it was never a problem..

 

Edited June 23, 2022 by RuskyV

[Terzi]

 

[BIGNEWY]

I will ask the team but I dont think there is any issue, if we have evidence I'm happy to check it out some more, but if its just feelings it make things more difficult.  

[darkman222]

Can't look at the track file at the moment either. But the F16 FLCS acts different with gear down compared to with gear up

[777coletrain]

I know I don't have any numbers specifically for the F16. However if you ask your SMEs if they use rudder to maintain coordination in the pattern I would be surprised if they said "yes"

[777coletrain]

Has there been an update with this? Looking at it in the external view it looks like the rudder is trying to adjust for the adverse yaw but it isn't doing much to help. It would be really nice to not have the nose wiggling all over the place in the pattern

Edited June 29, 2022 by 777coletrain

[BIGNEWY]

Hi all, 

the team have taken a look and agree it needs some tweaking. 

Thank you

[777coletrain]

There is still a high amount of adverse yaw in the F16 when the gear is down. I would expect the airplane to be much more stable due to the FLCS automatically adding the required rudder input. 

F16 YAW 10 12 22.trk

[BIGNEWY]

posts merged, we did have a fix for this already and I have asked the team to take a look at your track replay

thanks

[BIGNEWY]

11 hours ago, 777coletrain said:

There is still a high amount of adverse yaw in the F16 when the gear is down. I would expect the airplane to be much more stable due to the FLCS automatically adding the required rudder input. 

F16 YAW 10 12 22.trk 515.34 kB · 4 downloads

So we have taken a look, on a normal approach there is no problem all seem correct as is, but in your example you are using maximum roll reversal on approach. 

do you have any evidence that in this case there would not be some yaw?

[777coletrain]

I was doing maximum roll reversals to demonstrate the issue for the report. I've done another flight with just a lap around the pattern and a fairly calm approach for this next one. I'd like to note how much the nose yaws right on the initial roll in the perch and how much it moves around when I roll out on final.

I'm not saying there should be absolutely zero adverse yaw, but the f-16 in DCS has a lot more than the HUD tapes I've seen. Granted, I'm assuming the pilots in videos I've seen (and the one I'm linking) are using zero or minimal rudder which would align with my personal experience with fly by wire aircraft. I would love to be able to provide you with better evidence however, not having flown the thing for real we need to resort to asking people who have flown it how much rudder input is used in a normal pattern to land. 

 

I'd like to note how stable the nose is when rolling with the gear down and how little yaw there is after rolling wings level.

F16 YAW2 10 15 22.trk

[BIGNEWY]

I will run it by the team again, but a video is not proof that something is wrong here. We dont know the weather, weight, loadout, or what inputs the pilot was making.

[777coletrain]

I agree a single video isn't proof which is why I'm asking for you to talk to your SMEs. It really feels like there is a lot of adverse yaw for a FBW system. I've also seen it be very noticeable when you try to do small changes left and right (like a slight left turn to lock in centerline on an approach)

Edited October 25, 2022 by 777coletrain

[BIGNEWY]

On 10/21/2022 at 3:44 PM, 777coletrain said:

I agree a single video isn't proof which is why I'm asking for you to talk to your SMEs. It really feels like there is a lot of adverse yaw for a FBW system. I've also noticed it be very noticeable when you try to small changes left and right (like a slight left turn to lock in centerline on an approach)

 

We have not had a single SME complain about this. 

 

[777coletrain]

I appreciate you bringing this to the team and look forward to their response. 

[777coletrain]

Have there been any updates with this?

[BIGNEWY]

On 11/25/2022 at 6:43 PM, 777coletrain said:

Have there been any updates with this?

We have not had any evidence to support it, and as mentioned our SME's have not mentioned it as a problem. 

[777coletrain]

Ok, did you ask your SMEs about this or are you waiting for them to bring it up to you?

[Deano87]

I asked my brother about this, who has around 500hrs on the Viper and this was his reply.

"The real F-16 has no adverse aileron yaw worth mentioning in any symmetrical configuration. It has a computer specifically designed to keep the pointy end forward, and it does it quite well.

It should roll around the velocity vector and the FLCS should do everything needed to keep the ball centered while it's doing it. While the FLCS does function differently in landing gains the ARI is still functional and should null all unwanted yaw and/or sideslip."

Please bring this up to your SMEs.

Edited December 2, 2022 by Deano87
spelling typo

[llOPPOTATOll]

How is this issue [correct as-is] [fixed] and [reported] all at the same time

[BIGNEWY]

4 hours ago, llOPPOTATOll said:

How is this issue [correct as-is] [fixed] and [reported] all at the same time

It was initially reported, we then had a fix, and subsequently is correct as is when it was questioned again.

I have removed the reported, it is now fixed, and correct as is

[777coletrain]

On 12/1/2022 at 6:45 PM, Deano87 said:

"The real F-16 has no adverse aileron yaw worth mentioning in any symmetrical configuration. It has a computer specifically designed to keep the pointy end forward, and it does it quite well.

It should roll around the velocity vector and the FLCS should do everything needed to keep the ball centered while it's doing it. While the FLCS does function differently in landing gains the ARI is still functional and should null all unwanted yaw and/or sideslip."

This has been what I've been hearing also

Edited December 7, 2022 by 777coletrain