Rudder moves when rolling, making the aircraft unflyable [solved]

[Rixan]

Something strange is happening to my F-15 and only to that module: if I move ailerons, the rudder moves in the opposite direction for no reason.

What makes this issue crazy is that this behavior happens even when flying just with keyboard controls, having unplugged my hotas and rudder pedals and with respective controls' category cleared! Tried also to clear the default keys for rudder (Z & X) with no success.

 

I just did a clean reinstall, deleting also the user's folder, but nothing helped.

 

Here's a video I recorded to show what happens when turning: I never touch the rudder and I did the test just using the keyboard as control 

 

 

Can anyone please tell me what's going on with my F-15 and if there is a solution?

Any advice will be much appreciated.

Edited January 15, 2021 by Rixan
added Video evidence

[GGTharos]

There's nothing crazy about it.  This is the aileron-rudder interconnect which manages the rudder together with the ailerons, just like in the real aircraft.

 

The solution is to stop flying to AoAs that are mostly uncontrollable, which is what you've done.  There's no FBW to finesse that here for you, you have to do it yourself.  Reduce back-stick until you're out of the AoA warning tone area.

Edited January 14, 2021 by GGTharos

[Rixan]

So is it perfectly normal that the rudder moves when moving the stick, even on ground??

I tried to pull less and flying with lower AoA, and I dramatically loose speed resulting in an early stall.

 

I don't know, maybe it's just me, I can't fly an F-15, but I don't remember such strange behavior and rudders moving so much while turning.

[GGTharos]

What else have you flown?   I don't know why you're losing speed dramatically if you have less AoA.  In the video you posted, you've already blown all your speed by being ham-fisted.  You've got AoA so high that neither rudder nor aileron wants to work for you, and you're not trying to finesse.

 

Pardon my assumption here but, to me it looks like you're used to FBW aircraft and it's not that you don't know how to fly an F-15, you just don't know how to fly.  FBW aircraft protect you (mostly) from what you've done here.

 

You've started this flight at 350kts and made a full stick turn.  Try again, this time only put enough stick so you don't lose speed at all.  Yes, that's a slow turn.  It doesn't mean you can't make a harder turn, just practice that one for now, then you can practice adding a little more stick to have a turn that bleeds speed slowly.

 

Long story short:  You're flying ham-fisted.   

[Rixan]

First of all, thanks GGTharos for your valuable feedback and precise analysis.

I have flown Mig-21, F-86, A-10A/C, F-18, MB-339, F-14 lately. I still don't master those great modules, but I'm slowly learning step by step.

 

I tried again, this time re-binding my hotas and rudder as before the reinstallation, and it felt natural, as it has always felt. 

 

I don't know what solved that strange behavior which, I have to admit, in the video evidence seemed to be caused by the forced AoA (I can't fly using keyboard, that's why I flew ham-fisted), but in those conditions I really couldn't fly the F-15 as I used to do, even with my Hotas.

 

I knew about the aileron-rudder interconnect, but I imagined it as a subtle interaction: so, my fault for the lack of "situation awareness" in the F-15 after a while I didn't fly it regularly

 

Problem solved then! 

[GGTharos]

You're welcome.  It was a bad assumption on my part then - if you're flying the MiG-21 and F-14, you're probably not a particularly ham-fisted pilot

 

I'm glad it's resolved.   Yep, the ARI is a thing but there's certainly a case to make for some weird button/axis assignment that would move the rudders in addition to the ARI, which could be what happened to you.   The ARI does have come limitations, but IIRC at slow speed it is allowed full deflection - probably at high AoA also, since at high AoA you want to use the rudders and not the ailerons.  Don't quote me on any of that, it's been too long since I've seen the ARI schedules

Edited January 15, 2021 by GGTharos

[draconus]

ARI engages when pitch displacement is paired with aileron displacement. It's more pronounced with flaps out. The ARI disengages when over M1.0, during landing rollout and when the landing gear is down with anti-skid switched off.

[Source: -1]

 

It's even possible to have throttle-stick interconnect out of the box in DCS when you have a few devices connected You have to manage controls to avoid cross-controls and binding conflicts.

[Rixan]

Thanks for clarification gents, now I learned something new.

 

I'm aware of binding conflicts i.e wrong/multiple axis and buttons assigned to wrong peripherals, and that's why during testing I unplugged everything and cleared all the bindings except default keyboard keys.

[Northstar98]

FWIW the Su-27 and probably the -33 does the same thing.

Edited January 15, 2021 by Northstar98