Weird drifting issue.

[JagHond]

Greetings to all.

Since the first time I began to fly the Viggen, I'm experiencing a strange issue happening with this plane only. Since I start moving and taxiing, my plane is 'drifting' (hope this is the correct term to explain this. English isn't my native language, sorry for that) to the left.

This issue is getting worse when increasing the speed, i.e. at takeoff.

When in flight, I can't avoid to trim the plane heavily and costantly, using the autopilot is out of discussion, of course. Things get better if I switch to full autopilot (direction+altitude), but even so I have to watch out carefully and make route corrections costantly.

I can confirm that this strange behaviour is related to the Viggen only, I have the Mirage installed and nothing of the like ever occurred.

My HOTAS is a Saitek X-56 and I've checked carefully its settings, but I found all in order and working correctly.

And I have subtle suspsicions that Viggen's flight performances might be less than the ordinary ones expected, I can't rise it in altitude at wish.

What am I missing, and what should do more or better now?

Thanks anyone for your precious advises in advance.

With best regards,

[hideki2]

You mean drift in the yaw axis? I have also noticed that a long time ago, but I always treated it as a aerodynamic gimmick of Viggen. It never really bothered me and you can fix it with rudder trim.

[JagHond]

Thanks for your kind reply. Yes, that's just it.

I already tried doing what you suggested to, but with no results - that issue is still and always there.

I can't do flying and trimming continously the plane at the same time.

 

Something must come first, do you agree?

With best regards,

Edited September 26, 2018 by JagHond

[Eldur]

Well at least the autopilot should stay on course, but it doesn't. I noticed this issue is most pronounced when carrying 4 BK M-90s and almost nonexistent with a clean Viggen so I guess the issue is generated somewhere with the stores.

[RagnarDa]

Carrying Bk90 on the fuselage stations makes the airplane aerodynamically unstable, hence it was never carried this way IRL. Also, double check your axis-bindings.

[JagHond]

Thanks for the hint, Ragnar.

But I already checked those bindings several times. No results, and the issue is still there. If this really is an issue, only hope that you or you guys at Heatblur sooner or later can fix it.

With best regards,

Edited September 29, 2018 by JagHond

[RagnarDa]

Could you maybe upload a track of a flight so I can see it?

[unknown]

Thanks for the hint, Ragnar.

But I already checked those bindings several times. No results, and the issue is still there. If this really is an issue, only hope that you or you guys at Heatblur sooner or later can fix it.

With best regards,

 

Can you please post the mission and a track file showing this problem? I tried a simple mission - aka placed a Viggen on a runway in the ME with 4 BK90 loaded - and did a takeoff and flying to some waypoints and i had no drifting to any side, it rolled down the runway dead center without any control input.

The only time i get a drifting to one side at the takeoff is with crosswind set in the ME and that is expected. With wind set in the ME i can also see a little oscillation with the AP set but nothing uncontrollable, could of course be worse with stronger wind settings.

[JagHond]

Could you maybe upload a track of a flight so I can see it?

Thanks for your attention (and to unknown also, of course).

I'm still not an expert in this, but I'll try to do my best.

Try this (or please let me know if it doesn't fit for your purposes): Viggen CCIP bomb attack.trk

With best regards,

Edited October 1, 2018 by JagHond

[unknown]

Hi JagHond,

i had a quick look at your track, just watched until you turned right after your takeoff. I will have a look at the whole track later.

 

If the track is playing correct for me i have some things that cought my eye.

Picture 1:

- you are on the runway pushing the throttle forward for your takeoff

- i have activated the control input window

- as you can see, your rudder is not centered

- also your joystick is often not centered

- you disabled SPAK - why?

- SPAK is your automatic dampening system - it's like you would turn off the Fly-By-Wire System in the F-18 - the manual states that it should be engaged all the time

 

In Picture 2 and 3 you can see that your rudder will not center correct, it looked like as if you were fighting the Viggen. I think your problem at the takeoff is the rudder input to the left, the Viggen is drifting to the left and you try to compensate for that and wiggle left and right until you are fast enough to takeoff. Even in the air your rudder has a slight left input.

I did a quick takeoff from the same runway. If the track is replayed correct you should see the control input window while i takeoff. The Viggen should takeoff without drifting to one side, i never touched the rudder for the whole flight and you should see the little joystick input you need for the takeoff.

Maybe you should add a small deadzone for your rudder (and joystick?).

[RagnarDa]

You might also want to try calibrate both your rudder and joystick:

https://www.howtogeek.com/241421/how-to-calibrate-your-gaming-controller-in-windows-10/

[JagHond]

Thanks for your quick replies.

@Ragnar: I already have calibrated several times my X-56 just following that Windows procedure, but after that the issue remained.

@unknown: you are right, nut the issue is just that, the rudder is drifting continuously to the left. But what's really weird is that it's acting this way with the Viggen only and especially when SPAK is enabled, when the effect dramatically increases.

Weird, isn't it?

I'm open to any suggestion, mates...

With best regards,

Edited October 2, 2018 by JagHond

[unknown]

Thanks for your quick replies.

@Ragnar: I already have calibrated several times my X-56 just following that Windows procedure, but after that the issue remained.

@unknown: you are right, nut the issue is just that, the rudder is drifting continuously to the left. But what's really weird is that it's acting this way with the Viggen only and especially when SPAK is enabled, when the effect dramatically increases.

Weird, isn't it?

I'm open to any suggestion, mates...

With best regards,

Very weird.

 

My advice would be to add a deadzone to your rudder axis within DCS.

Go to your control options, select the rudder and click on AXIS TUNE. Watch the red dot moving on the Axis as you wiggle your rudder a little at the center point of your physical rudder pedals. Increase the deadzone as much as you need to compensate for unwanted control inputs.

I have a small deadzone for my rudder pedals for all moduls because just moving them 1mm will result in a rudder movement in game.

 

And after adjusting that, have fun with this beauty. :joystick::pilotfly::D

[JagHond]

Thanks to you too for your attention, unknown.

You're right, it's just weird. I never experienced an issue like this before.

And I'll follow your advise, who knows if something will change in good at last - if that could become less it would be fine the same.

With best regards,