XP11 winds, aircraft and weathervaning ...

[jcomm 5,916]

While Murmur continues his study of the data available from XP11 dataref database, I would like to point out a couple of findings I did today, and contribute to restore, considerably, my hope in XP11 at least in this particular matter!

 

Well, since Murmur suggested there might be some problem with the default C172, I decided to pick the default B58.

 

Placed it at LPMT rw 08, braked, engines out, and started playing with the "wind rose", which, btw, reminds me more of the way DCS World interface is designed to define wind direction, and I don't find that good, because it can be misleading - the the arrow point to "from where" the wind comes, but being an arrow, this can be misinterpreted as "where to"... Anyway, here go my findings:

 

1) The trim settings, both default Plane Maker trim tab settings and whatever we set in the cockpit using the trim wheels / switches when available, deflect the corresponding control surfaces from there "neutral" position, with any wind intensity washing them, from 0 to the max available wind component + max gust.

 

I really don't recall how it was in previous versions ( ? )

 

If, for instance, you set the ground adjustable aileron trim tab to a huge +4.00 instead of the default +0.07, when you look at the aircraft from an outside view, the ailerons will be considerably deflected accordingly, in this particular case, the right aileron deflect UP the left deflected DOWN. This does not depend on there being any propwash ( the engines can be turned off ), or wind component.

 

I do not like this approach, and I believe Austin should create a better representation of the effect of trim surfaces, namely, their effect being noticeable only as dynamic pressure increases over their surfaces... The ailerons with the parked aircraft should be neutral, but for instance by increasin the wind from ahead to higher and higher values, they should start to deflect...

 

2) When a x-wind component is set in the weather menu ( make sure you disable NOAA or any other weather injector to run the tests, or their settings will prevail! ), the rudder will deflect upwind !  Now, this is irrespective of what the default trim tab position is ( in the case of the default Baron 58, rudder and elevator trim tabs are set at 0.00 in Plane Maker ).

 

Now, 2)​ can in some way be the culprit for the overdone need to use downwind rudder input.

 

But, looking at the effects of the wind, specially set at "stronger" values, from the outside of the aircraft, and how the gear struts compress and the tire physics work, is really promising!

 

Looking forward for your comments, and for Murmurs tests, but I wonder if anything can be done, other than using artificial stability, to avoid the rudder deflection upwind with a x-wind component ?

 

The screenshot bellow shows the default Baron 58, parked at LPMT rw 08, with a wind set at 35 knot from port side. Notice the rudder deflected upwind. The ailerons are also deflected, not because of the wind but rather because I defined the aileron trim tab in Plane Maker to +4.00. The yoke and the rudder in the cockpit remain centred.

 

[jcomm 5,916]

Or... maybe Austin got his inspiration from this...

 

https://www.youtube.com/watch?v=9IdIaEwwCZs

 

[Alfredo Fernandes 1]

I guess rudder is deflecting with wind because you have stability augmentation?

[jcomm 5,916]

I guess rudder is deflecting with wind because you have stability augmentation?

 

negative - I did make sure it was all at 0%.

 

And, even if it was AS, it would then deflect it opposite :-)

[Humpty 751]

was that a 100 kt wind ? that aircraft was blown away like it's paper 

 

All my sliders are to the left 

[jcomm 5,916]

was that a 100 kt wind ? that aircraft was blown away like it's paper 

 

All my sliders are to the left 

 

In the youtube, I don't guess what winds were on both videos.

 

In my screenshot, just 35 knot effective x-wind from portside.

[Alfredo Fernandes 1]

Not sure if I understood, but I tried to have 40kts from any sides for test and didn't got any deflections on rudder? the only thing that happens is gear compression, so maybe something else is affecting your side to get rudder deflection with wind?

[Humpty 751]

that small aircraft in that video which was blown away with the wind , that must have been the headwind causing great lift , heck it overcame the gravity on the mass. 

 

 I guess the tire friction fixed mentioned may have had something to do with the weathervane effect not that i understand much about it.

Have you looked for this effect in DCS ? 

[jcomm 5,916]

Not sure if I understood, but I tried to have 40kts from any sides for test and didn't got any deflections on rudder? the only thing that happens is gear compression, so maybe something else is affecting your side to get rudder deflection with wind?

 

Weird ? Did you try with the default Baron58, making sure only X-Plane weather is being used and no external injector ? The tests I made were with beta3, and Art Stab full left for the three axis.

 

 

that small aircraft in that video which was blown away with the wind , that must have been the headwind causing great lift , heck it overcame the gravity on the mass. 

 

 I guess the tire friction fixed mentioned may have had something to do with the weathervane effect not that i understand much about it.

Have you looked for this effect in DCS ? 

 

Yep, DCS, Il-2 Battle of, Rise of Flight, Aerofly FS 2, FSX, P3D Aerowinx PSX all model it, DCS, IL2 and Aerowinx PSX with very good detail, including strut compression, and in IL2 and DCS, some really interesting results from propwash interference with various aircraft surfaces...

[Humpty 751]

Yep, DCS, Il-2 Battle of, FSX, P3D Aerowinx PSX all model it, DCS, IL2 and Aerowinx PSX with very good detail, including strut compression, and in IL2 and DCS, some really interesting results from propwash interference with various aircraft surfaces...

 

Strut compression  think has been fixed with the B3 but i can't be sure, yes DCS does model compression. 

 

I think read on one post about the weathervane issue i think in the Xenviro thread.

[jcomm 5,916]

One important note though!

 

On my tests I had no hardware controllers in place, just use the mouse and keyboard to fly XP11 in a laptop where I keep a copy...

[Pascal_LSGC 298]

There's probably some autocoordination in play, then.

 

 

One important note though!

 

On my tests I had no hardware controllers in place, just use the mouse and keyboard to fly XP11 in a laptop where I keep a copy...

 

 

Cheers,

Pascal

[bonchie 2,305]

The deflection is definitely an issue and it makes sense as to why you see weathervaning on the ground while taxiing as the rudder movement and nose wheel are coupled in the simulation.

In real life, the forces on the rudder via it's rigging are not going to allow such a deflection to happen, especially since you'll also have pressure with your feet also being applied keeping it centered.

 

This issue is old and I'm shocked it still exists. Austin needs to prioritize this. It's a big black eye for XP and is the first thing that new players experience.

[Humpty 751]

How can i check ? 

[jcomm 5,916]

How can i check ? 

 

Place the aircraft ( Baron 58 i.e., or even the C90 although I didn't test with this one ) on a rw, shutoff the engine, disable any weather injcetor and set a near ground win layer at 90º from left or right.

 

Get into na exteranl view and observe.

 

Make sure Artificial Stability is off ( 0% = full left on the three axis )

 

But, Pascal above mentioned autocoordination ? I don't know how to enable that in XP11 ?  And I didn't have any joystick or rudder attached - just use the mouse & keyboard, and my controls were centred.