Okay, I found an issue that might explain some of the extreme right rudder with the 172, and maybe some other ground handling things. Or maybe not. 

 

Here's the deal. In XP10, we used to set winds in discrete layers. Whatever you set in one of the three layers didn't affect the other layers. In XP11 it appears to be different. If there is a single wind layer at high altitude, it affects everything below it right down to the ground. 

 

I noticed this when I used X-Plane's default real world weather update, which set very high winds at high altitude and another couple of layers below that. The lower levels were still too high (at this time of year in the PNW), so I manually deleted them, leaving the top layer because I was never going to fly that high anyway. But I got severe weathervaning and uncontrolled handling on the runway. This was with the S-76 helicopter but it happens with the 172 also. I fixed it by manually adding a wind layer at ground level set to 0 kts. 

 

So if you're getting too much weathervaning or other uncontrolled handling at takeoff, double-check your wind layers in the weather setting. They no longer affect just the layer they're set at, like they did in XP10, but everything underneath until they hit another added wind layer.

 

I suppose this isn't a bug, just a new way to think about how the weather system works.

Okay, I found an issue that might explain some of the extreme right rudder with the 172, and maybe some other ground handling things. Or maybe not. 

 

Here's the deal. In XP10, we used to set winds in discrete layers. Whatever you set in one of the three layers didn't affect the other layers. In XP11 it appears to be different. If there is a single wind layer at high altitude, it affects everything below it right down to the ground. 

 

I noticed this when I used X-Plane's default real world weather update, which set very high winds at high altitude and another couple of layers below that. The lower levels were still too high (at this time of year in the PNW), so I manually deleted them, leaving the top layer because I was never going to fly that high anyway. But I got severe weathervaning and uncontrolled handling on the runway. This was with the S-76 helicopter but it happens with the 172 also. I fixed it by manually adding a wind layer at ground level set to 0 kts. 

 

So if you're getting too much weathervaning or other uncontrolled handling at takeoff, double-check your wind layers in the weather setting. They no longer affect just the layer they're set at, like they did in XP10, but everything underneath until they hit another added wind layer.

 

I suppose this isn't a bug, just a new way to think about how the weather system works.

 

I think the wind layers aren´t any layers with much thickness - they are just very thin slices where the set conditions apply. Anything in between are probably interpolated. In absence of other layers, the single layer at 35000 will propagate all the way above and below...

 

Just my take, not sure, tough.

 

Jan

I'll double check, but I was using the default Clear weather theme ... but your find might explain some of it, have to verify.

 

Cheers, Rob.

I think the wind layers aren´t any layers with much thickness - they are just very thin slices where the set conditions apply. Anything in between are probably interpolated. In absence of other layers, the single layer at 35000 will propagate all the way above and below...

 

Just my take, not sure, tough.

 

Jan

 

Yes, that's how I thought they worked in XP10 ... their implementation of Winds Aloft isn't accurate to real world but just interpolated from NOAA value at 3000 and at 39,000 (or maybe 34,000).  Winds don't work that way per NOAA (3,4,9,12,18,24,30,34,39k ft values) ... but in either case the winds aloft data is only from 3000 ft on up, not surface winds.

 

Cheers, Rob.

What was wrong with them ? I havent seen any issues

I was getting less than 5 fps on some payware airports with AA enabled. It's all good now.

I think the wind layers aren´t any layers with much thickness - they are just very thin slices where the set conditions apply. Anything in between are probably interpolated. In absence of other layers, the single layer at 35000 will propagate all the way above and below...

 

It looks like that's how it works now. There might be interpolation between different layers, but if there's just one layer it applies to any altitude, not just the general area where it's set.

 

Try setting a single high altitude wind layer at 40,000 feet for 50 kts with 50 kt gusts, and see if you can take off in a 172 at sea level.  :smile:

X-Plane 11, the last time I tried it, weathercocks the C172, fully loaded, on a mild quartering 5knot wind, the moment you release the brakes!

 

C'mon.... this is the sort of things I can't accept from a flightsim, developed by a rw GA pilot... I really can't believe Austin doesn't notice how wrong it is, and even less why he hasn't found a plausible fix, since XP9 !!!

 

Most users which are newcomers to X-plane probably don't even know they are using the sim by default with 50% of Artificial Stability on all 3 axis, which even contributes to soften the effects. Reduce it to 0% as you should, and things get even worst...

 

Park your C172, the default or the best there is for X-plane right now, release brakes - just that ! - and if a wind quartering at no more than 5 knot is present, even less..., the aircraft will weathercock into it....

X-Plane 11, the last time I tried it, weathercocks the C172, fully loaded, on a mild quartering 5knot wind, the moment you release the brakes!

 

C'mon.... this is the sort of things I can't accept from a flightsim, developed by a rw GA pilot... I really can't believe Austin doesn't notice how wrong it is, and even less why he hasn't found a plausible fix, since XP9 !!!

 

 

I'm yet to try and explore new beta. But did you guys use control surfaces to correct for the wind on the ground? Just curious 

I'd like to also point out that I'm also getting better performance across the board with XP 11 b3. Better visuals & better performance than XP 10.

I'm yet to try and explore new beta. But did you guys use control surfaces to correct for the wind on the ground? Just curious 

 

 

IRL, at least where I usually fly from, if your Cessna weathervanes in the parking lot as you release brakes, for sure you will cancel your intentions to go flying. For students, a x-wind component of 8 knot - 8 knot component from 90º port or starboard, is the limit for a 172 there... Yet, taxiing with a 8 knot wind will for sure not weathercock your 172 on the taxiway, even if yes, you may feel some need to input a bit of rudder / aileron for good taxing practices under wind....

My 172 requires full right rudder regardless of wind speed or direction.

If you assume there's no tire friction, an aircraft would weathercock into the wind...well...like a weathercock.  So this is related to the tire friction model correct?

Maybe this is expected with the betas, but previously saved .sit files no longer will open in the new beta.. incompatibility.

IRL, at least where I usually fly from, if your Cessna weathervanes in the parking lot as you release brakes, for sure you will cancel your intentions to go flying. For students, a x-wind component of 8 knot - 8 knot component from 90º port or starboard, is the limit for a 172 there... Yet, taxiing with a 8 knot wind will for sure not weathercock your 172 on the taxiway, even if yes, you may feel some need to input a bit of rudder / aileron for good taxing practices under wind....

 

Once I was taxing in 172 during high wind conditions (locally called Santa Ana) with a nice direct crosswind. At some point after landing tower asked me to exit to the left for a taxiway. I couldn't turn airplane to that direction with all crosswind controlls full and left break jammed LOL Anyway I don't think it's correct modeling in XP. I'm just curious if cross wind effect is exaggerated so you have to use same crosswind technique while you taxi with 5 kts wind as you do with 20kts

My 172 requires full right rudder regardless of wind speed or direction.

 

While taxing on the ground?

If you assume there's no tire friction, an aircraft would weathercock into the wind...well...like a weathercock.  So this is related to the tire friction model correct?

 

I don't think so. I tried setting a 5kt crosswind at 0 deg. with the 172 on a runway heading of 90 deg. Released the brake, and it started weathercocking into the wind. But there is a forward motion component too.

 

I tried it again using the external camera looking straight down from overhead. If it was a problem with too little tire friction, the plane would just rotate in place (I think?). Instead it rolls forward slowly while turning after the brake is released.

 

Note: this weathercocking is there, but it's barely noticeable for me. I can still taxi and takeoff with just a touch of right rudder pedal. So I don't know why people are needing extreme amounts of right rudder (or that PLUS aileron?) to taxi and takeoff in the 172.

 

I doubt whatever is happening there is the flight model, or it would affect everyone the same way. But we are using different controllers (Saitek Pro Combat pedals in my case). So I think the answer has to be in how XP11 is reading those different controller inputs.

No change in performance here, but the mis-shaded trees seems to be fixed, so I'm happy :-)