Rudder trim moves the rudder, even with no airflow...

[Anatoli-Kagari9]

In the Spitfire, using v2.1.1, when CTRL-ENTER is used to track the control surface deflection, we can notice that as rudder trim is set, even with the aircraft stopped on ground, and the engine stopped as well, the rudder moves.

 

In modules like the p51d, surface deflection only used to happen when there was enough airflow over the trim tabs.

Edited August 10, 2017 by jcomm
Solved with latest patch

[Chrinik]

Are you sure it´s not a mechanical system that does directly affect the rudder position?

[Anatoli-Kagari9]

I'm not 100% sure how it works, but I don't believe that's the case since there's a tab in the rudder.

 

Maybe the Devs can confirm ( ? )

Edited August 9, 2017 by jcomm

[Art-J]

Jcomm's right, it's just a basic trim tab system.

 

However, I can't confirm the initial observation, at least after today's update (haven't payed attention to it earlier) - both indicator and rudder deflect only under sufficient airflow.

[Anatoli-Kagari9]

Art-J,

 

thx for the feedback ! I will check it then, as soon as I get today's patch in my DCS PC, which will probably happen only tomorrow night :-/

[Captain Orso]

What you are describing are Flettner tabs. https://history.nasa.gov/monograph12/ch6.htm See the section "Flettner Tabs, Servo Tabs, Spring Tabs, and Whirlerons" for explanation and diagrams.

[Anatoli-Kagari9]

What you are describing are Flettner tabs. https://history.nasa.gov/monograph12/ch6.htm See the section "Flettner Tabs, Servo Tabs, Spring Tabs, and Whirlerons" for explanation and diagrams.

 

Thx,

 

and yes I was aware that it is a Flattner type tab, but those only work as force reduction mechanisms for when the controls have to be moved at higher dynamic pressure values - they do not directly move the main control, and act in that way just as any other trim tab.

 

The effect I was seeing, before this last patch, was that by only moving the rudder trim tab, even with the aircraft on ground and engine off, the rudder also moved. It Works ok now.

Edited August 11, 2017 by jcomm

[Captain Orso]

Ahhh okay, I misunderstood that. That would be weird.

 

I thought the issue was ailerons, elevators, and tail rudder moving, without the airflow to actuate Flettner tabs.

 

I tried to find some information on if the Spitfire has spring tabs, or even gear spring tabs, but couldn't find any. I kind of think it must have one of those two, otherwise you'd have basically no control over the aircraft while taxiing, other than through using the breaks. But aside from my experience flying the DCS Spitfire, everything I've read strongly insinuates that you not only have use of those control surfaces, but that you must absolutely master them to maintain control on the ground and especially while taking off.

[Sokol1_br]

Adjust the trim tabs without engine running make no movement in control surfaces:

 

Elevator:

 

 

Rudder at ~2:06