Bf-109 k4 aileron roll right

[grafspee]

Can someone explain to me why as soon DCS K-4 get speed higher then 100kph stick deflect it self to the right making right aileron roll ?

I just can't grasp it why this is happening, in special tab aileron trim is set to 0.

I would be very happy if anyone help me understand this.

No other DCS warbird has this characteristic.

Edited December 15, 2023 by grafspee

[Xupicor]

I don't get that behavior at all. Are you sure you don't have a spurious axis on aileron or rudder that's interfering? With 100km/h I can't imagine you're talking about anything else but a take-off roll -- if anything, there's a tendency to aileron roll left if you pull on the stick instead of letting it rotate on its own.

Can you upload a track?

[grafspee]

Problem is in flight i have to constantly deflect stick to left or with rudder set slip worth whole ball in order to fly level.

This problem is with me since i bought this module and only solution for this is to set up something like -27 aileron trim in special tab.

I can't think a single reason why ailerons deflects it self as soon as 100khp is reached.

 

right roll.trk

Edited December 16, 2023 by grafspee

[Gadreel]

Flight Manual page 35 + page 37 explain it. 

[grafspee]

1 hour ago, Gadreel said:

Flight Manual page 35 + page 37 explain it. 

DCS mention only something on not even forces acting on stick due to lack of elevator trim tab ? Is it what you had on mind. I can't find anything else.

[Gadreel]

From the manual:

"The 109 K series featured Flettner tabs on serial production aircraft to reduce control forces, but these were often not fitted to production examples, with many of the K-4s using the same aileron system as the G series. Some aircraft rolled off the production line with only ground-adjustable aileron Flettner trim, but no elevator trim, which resulted in uneven force distribution on the stick, making control more difficult at higher speeds." 

From another thread: 

"German fighters in general did not have in-flight adjustable aileron and rudder trims.

Only ground-adjustable (bent by mechanics) ones are available on K-4. By default the plane is set to fly relatively straight with cruise parameters (a bit above 1 ATA of boost and ~400 kph IAS), but you can change adjustment in "special" settings tab with trial and error method." 

 

So my understanding is that it is intended to work like this, because it´s how it was in the real aircraft. The DCS special option for thr BF 109 to set ailron and rudder trim simulates the mechanic setting the trim flapon the ground the way the pilot wanted it to be. 

That way you can choose at what speed you want the plane to fly straight without stick force. 

[grafspee]

12 minutes ago, Gadreel said:

From the manual:

"The 109 K series featured Flettner tabs on serial production aircraft to reduce control forces, but these were often not fitted to production examples, with many of the K-4s using the same aileron system as the G series. Some aircraft rolled off the production line with only ground-adjustable aileron Flettner trim, but no elevator trim, which resulted in uneven force distribution on the stick, making control more difficult at higher speeds." 

From another thread: 

"German fighters in general did not have in-flight adjustable aileron and rudder trims.

Only ground-adjustable (bent by mechanics) ones are available on K-4. By default the plane is set to fly relatively straight with cruise parameters (a bit above 1 ATA of boost and ~400 kph IAS), but you can change adjustment in "special" settings tab with trial and error method." 

 

So my understanding is that it is intended to work like this, because it´s how it was in the real aircraft. The DCS special option for thr BF 109 to set ailron and rudder trim simulates the mechanic setting the trim flapon the ground the way the pilot wanted it to be. 

That way you can choose at what speed you want the plane to fly straight without stick force. 

Thing is that aileron trim is not affected by speed or power at all. If i set aileron trim to 0 as default it will roll right all the time and deflection of aileron won't change at flying speed 200kph or 600kph same exact deflection, when i set -27 aileron trim it makes stick centered across all speeds, this is why i am curious about it. This is super weird for me because i would assume that if i set certain aileron trim it should change it's effects depends on speed.

Anyway my solution is to set -27 aileron trim in special tabs then K-4 flies level when ball on slip indicator is centered. But still it bothers me because i don't know why this is happening, this right stick deflection appears even if you taxi K-4 with high speed, if you taxing with 50kph you start seeing stick deflect to the right super weird at so low speed.

Edited December 16, 2023 by grafspee

[Gadreel]

7 minutes ago, grafspee said:

Thing is that aileron trim is not affected by speed or power at all. If i set aileron trim to 0 as default it will roll right all the time and deflection of aileron won't change at flying speed 200kph or 600kph same exact deflection, when i set -27 aileron trim it makes stick centered across all speeds, this is why i am curious about it.

I don't know the technical reason for this. Maybe engine torque? But I am neither pilot nor engineering so not competent. I thought the behaviour is intended. I struggled with this as well (constant rudder and stick input needed). My settings are now aileron trim -25 and rudder trim -5. 

[grafspee]

11 minutes ago, Gadreel said:

I don't know the technical reason for this. Maybe engine torque? But I am neither pilot nor engineering so not competent. I thought the behaviour is intended. I struggled with this as well (constant rudder and stick input needed). My settings are now aileron trim -25 and rudder trim -5. 

Engine torque or P-factor affect how plane flies but it can't deflect aileron. Rudder is used to cancel out most of unwanted effect of engine and prop but pilot is doing that via muscles or trim system.

Prop planes slide slip or other effects, not because engine or prop deflect ailerons or elevator or rudder but because it has uneven thrust and you correct it with rudder to cancel out slip or other effects via control surfaces, trim system or build in angle of incidence of horizontal and vertical stabilizer.

Beside prop wash can't affect ailerons, they are just too far from prop wash.

In my case i have good rudder pedals and i can with ease keep ball centered but constantly keeping stick little deflection to the left is exhausting.

Edited December 16, 2023 by grafspee

[Gadreel]

This thread may be helpful:

https://forum.dcs.world/topic/169380-experienced-bf-109-pilots-help-needed-right-roll-level-flight/

[Mike_Romeo]

On 12/15/2023 at 6:54 PM, grafspee said:

Can someone explain to me why as soon DCS K-4 get speed higher then 100kph stick deflect it self to the right making right aileron roll

Check your axis bindings, sounds like double bindings to me

[grafspee]

27 minutes ago, Mike_Romeo said:

Check your axis bindings, sounds like double bindings to me

Axis binding checked couple times only single bind.

[Dragon1-1]

2 hours ago, grafspee said:

Engine torque or P-factor affect how plane flies but it can't deflect aileron.

Of course it does affect roll. It does not affect ailerons because that's a different thing, but in all cases, if you're turning a propeller in front of the aircraft, the aircraft will want to turn the opposite way. This is countered with rudder, yes, but it also requires some aileron input, or at least it does in warbirds (in a Cessna, with its smaller prop, you likely won't feel it). A WWII fighter has an immensely powerful engine that creates very strong torque effects, in addition to propwash. It's a dynamic system which the pilot has to constantly compensate for to keep balanced, especially in German fighters which tend to lack trim systems except for tailplane adjustment. That's just how they fly, the aircraft should be roughly balanced at cruise settings, but even then, you'll more likely than not have to input some stick and pedal force.

[razo+r]

@grafspee You are talking about this, right? Where the stick is offset to the right by itself?

Because I'm curious aswell. I took this picture from the instant free flight without a joystick, keyboard only. So deadzone issue cannot be the cause.

[Dragon1-1]

Do you have any sort of assist on? That's the only explanation I can think of.

[razo+r]

18 minutes ago, Dragon1-1 said:

Do you have any sort of assist on? That's the only explanation I can think of.

No assists turned on, no game flight mode and the trims in the special settings are all at 0. 

[grafspee]

10 hours ago, razo+r said:

@grafspee You are talking about this, right? Where the stick is offset to the right by itself?

Because I'm curious aswell. I took this picture from the instant free flight without a joystick, keyboard only. So deadzone issue cannot be the cause.

Exactly. I went through all settings, like FFB etc turned them off, i set dead zones at 0.

No double binds what so ever no other controllers connected only rudder pedals, joystick and throttle.

This right stick deflection only depends on speed, it start to deflect at around 50kph and stops at 120-150 ish kph and stays that way in flight no matter you power setting or speed even if it is 700kph.

Only way to made stick centered is to set aileron trim to -27 in special tab but why this is happening, i have no idea and this bothers me if i don't understand what is going on here

9 hours ago, Dragon1-1 said:

Do you have any sort of assist on? That's the only explanation I can think of.

Same as @razo+r everything off.

Edited December 17, 2023 by grafspee

[Art-J]

Can confirm the same thing (without double assignments and assists). Anyone can by launching the game with controllers unplugged, starting any free flight mission in K-4 and enabling ctrl indicator. Diamond will be offset by a tiny bit in roll axis.

Never really noticed it till now despite owning the module since its release, but it seems to be there indeed. I don't remember if it was all those years ago.

Since the diamond symbol represents virtual stick position affected by trims and airflow, the only explanation I can think of is that "0" set in special options does not really mean a flush tab, but it's a start/reference measured relative to a tab surface which is already bent a little at some unspecified angle (and that one is hardcoded, we don't have access to it).

[razo+r]

15 minutes ago, Art-J said:

Can confirm the same thing (without double assignments and assists). Anyone can by launching the game with controllers unplugged, starting any free flight mission in K-4 and enabling ctrl indicator. Diamond will be offset by a tiny bit in roll axis.

Never really noticed it till now despite owning the module since its release, but it seems to be there indeed. I don't remember if it was all those years ago.

It's been in DCS for years if I remember correctly.

15 minutes ago, Art-J said:

Since the diamond symbol represents virtual stick position affected by trims and airflow, the only explanation I can think of is that "0" set in special options does not really mean a flush tab, but it's a start/reference measured relative to a tab surface which is already bent a little at some unspecified angle (and that one is hardcoded, we don't have access to it).

That seems to be it. If I put the aileron trim to -100, the stick will be deflected to the left, and with +100 even more to the right. Around -26 seems to be the middle position for in flight.

[grafspee]

4 hours ago, Art-J said:

Since the diamond symbol represents virtual stick position affected by trims and airflow, the only explanation I can think of is that "0" set in special options does not really mean a flush tab, but it's a start/reference measured relative to a tab surface which is already bent a little at some unspecified angle (and that one is hardcoded, we don't have access to it).

It appears to be the case, but why only K-4 other ww2 planes were equipped with ground adjustable tabs as well but we have no option to change those in game. So this aileron trim offset in K-4 has some historical background or this offset is random figure only just because we can change those trim tabs in special tab options?

Edited December 17, 2023 by grafspee

[Art-J]

No idea to be honest. Kurfy has indeed been programmed somewhat different compared ot other DCS warbirds in this regard. Looks like they experimented with this special option feature only once for this module and didn't expand it later.

Edited December 17, 2023 by Art-J