Wind components

[abax2000]

Wind components

I try to read vertical wind speed component using offsets 3478, 3518, but they are constantly zero (although ActiveSky injects up/downdrafts and thermals at the same time). (It also looks like 3470 and 3480 have strange readings (not as expected), but this not my immediate concern.)

Which offset can give what I am looking for?

Note: I am assuming that up/downdrafts, thermals, turbulence and windshear are simulated within FSX with a vertical wind component. Is this assumption true?

Airport elevation

Is there anyway to get the airport elevation of the airport that the aircraft is approaching (i.e. the nearest airport)?

[Pete Dowson]

I try to read vertical wind speed component using offsets 3478, 3518, but they are constantly zero (although ActiveSky injects up/downdrafts and thermals at the same time). (It also looks like 3470 and 3480 have strange readings (not as expected), but this not my immediate concern.)

You fail to mention which version of FS or FSUIPC, but I'll assume you mean FSX.

3470, 3478, 3480 are populated from SimConnect's variables AMBIENT WIND X, Y and Z respectively, read in m/s and completely unmolested by FSUIPC. Whether SimConnect reports them accurately or not I'm afraid I've no idea. That's why they are documented with such a question in the FSUiPC4 Offsets Status list. 3518 is a derived value so if the original is wrong, it will be too.

Which offset can give what I am looking for?

Have you tried the other wind component values in offsets 2DC8, 2DD0 and 2DD8? They don't refer to exactly the same things, but at least they have been confirmed as working, as the document shows. These are directly from the SimMarket variables AIRCRAFT WIND X,Y and Z, and are in ft/sec rather than m/s.

Note: I am assuming that up/downdrafts, thermals, turbulence and windshear are simulated within FSX with a vertical wind component. Is this assumption true?

If FS truly does simulate all those things then, yes, I would assume so too. The FSUIPC simulation of turbulence certainly asdds some vertical component but I'm not sure whether FS's does. And windshear may only be simulated by a sudden wind shift between two layers rather than the slow progression normally implemented.

]Airport elevation[/b]

Is there anyway to get the airport elevation of the airport that the aircraft is approaching (i.e. the nearest airport)?

For FSUIPC4, only, Check the "nearest airport" offsets at 0658. These used to be unreliable but a way was found to fix that (by direct reading of tables in FSX memory).

Regards

Pete

[abax2000]

Hi Pete and thanks for helping out.

It is FSX sp2 and FSUIPC 4.853 licensed.

I didn't use offsets 2DC8, 2DD0 and 2DD8 in the first place because I didn't spot them (I was looking with other keywords).

I did further tests and my take so far is as follows:

Wind components

Offsets 3470,3478 and 3480 seem to work. This goes for 3518 also, that gets updated instantly (no lag). These offsets give the wind components at the aircraft relative to a XYZ system bound to earth.

The figures in these offsets interpret as:

3470 (positive values +) -> west wind component

3470 (negative values -) -> east wind component

3480 (positive values +) -> south wind component

3480 (negative values -) -> north wind component

3478 (positive values +) -> updraft

3478 (negative values -) -> downdraft

Offsets 2DC8, 2DD0 and 2DD8 give wind components at the aircraft relative to a XYZ system bound to aircraft (so XYZ in this case are the pitch, roll and yaw axis of the airplane). The figures, relative to pilot's view) interpret as:

2DC8 (positive values =) -> right crosswind component (total wind component parallel to pitch axis, coming from the right wingtip)

2DC8 (negative values -) -> left crosswind component (total wind component parallel to pitch axis, coming from the left wingtip)

2DD8 (positive values =) -> headwind component (total wind component parallel to roll axis, coming from the aircraft nose)

2DD8 (negative values -) -> tailwind component (total wind component parallel to roll axis, coming from the aircraft tail)

2DD0 (positive values +) -> total wind component pushing vertical against the aircraft's upper wind surface (this includes up/downdrafts and winds parallel to earth)

2DD0 (negative values -) -> total wind component pushing vertical against the aircraft's down wind surface (this includes up/downdrafts and winds parallel to earth)

So, these values depend on the pitch attitude and bank angle.

For my purposes, and since/if these offsets work reliably, I have all I need: crosswinds from 2DC8, head/tailwind from 2DD8 (not exactly but close enough in level flight), up/downdraft from 3478/3518.

up/downdrafts, thermals, turbulence and windshear simulation

I thought that these are indeed simulated (successfully or not is another discussion).

I imagine that a turbulence is nothing more than an oscillating vertical component, isn't that true?

What would be interesting is what is the area that this simulation covers (by FSUIPC or AS for that matter).

"nearest airport" offset 0658

Found it, but I would need some help on how to read it. In FSUIPC monitoring only ICAO is readable. What would be a proper Lua syntax (e.g. ipc.readxxxx) to read all the parts of this offset?

I am particularly interested in airport elevation.

wind smoothing

going through these tests, I encountered again an issue I forget to ask you about for a long time:

although wind smoothing is enabled in FSUIPC (2sec per knot or degree), it rarely happens that I get wild fluctuations in wind direction (most of the times, and not speed). This happens always at low altitude, this time was 1500ft, and it is consistently reproducable with the same METAR. In all other cases (in upper altitudes etc) smoothing is always working (you can actually tell when FSUIPC dampening is taking place).

Any hints on this?

Thanks a lot (again) for your help

[Pete Dowson]

I did further tests and my take so far is as follows:

Wind components

Ah, good. Thanks for the feedback. I'll update the document with your details.

up/downdrafts, thermals, turbulence and windshear simulation

I thought that these are indeed simulated (successfully or not is another discussion).

I imagine that a turbulence is nothing more than an oscillating vertical component, isn't that true?

I think it is (or at least surely should be) oscillations in all three axes, If FSUIPC is applying this then it computes maximum deviations according to the absolute values and the turbulence grade, and varies horizontal direction and speed and vertical speed using a gaussian distribution.about the set value as a mean. I've no idea what FS does when it is doing it.

"nearest airport" offset 0658

Found it, but I would need some help on how to read it. In FSUIPC monitoring only ICAO is readable. What would be a proper Lua syntax (e.g. ipc.readxxxx) to read all the parts of this offset?

I am particularly interested in airport elevation.

Well, I'm not sure what it is you do not understand, but since the first of the 6 entries is the nearest, and it has its elevation at offset 0x0658 + 12, or 0x0664, and since it is provided in feet as a FLT32, you simply read it with ipc.readFLT(0x0664). What was the problem in understandng this?

wind smoothing

going through these tests, I encountered again an issue I forget to ask you about for a long time:

although wind smoothing is enabled in FSUIPC (2sec per knot or degree), it rarely happens that I get wild fluctuations in wind direction (most of the times, and not speed). This happens always at low altitude, this time was 1500ft, and it is consistently reproducable with the same METAR. In all other cases (in upper altitudes etc) smoothing is always working (you can actually tell when FSUIPC dampening is taking place).

Any hints on this?

No. I've never seen it happen, unless you are just experiencing the higher levels of turbulence and variance you can get near the surface. If you are seeing that there is none (eg via WeatherSet read-outs), perhaps you should send me the saved FLT and WX files, etc, so I can see what you mean? ZIP and send to petedowson@btconnect.com.

Regards

Pete

[abax2000]

Ah, good. Thanks for the feedback. I'll update the document with your details.

I didn't realize I was on unknown territory. I edited a little my previous post to be sure that is clear.

I think it is (or at least surely should be) oscillations in all three axes, If FSUIPC is applying this then it computes maximum deviations according to the absolute values and the turbulence grade, and varies horizontal direction and speed and vertical speed using a gaussian distribution.about the set value as a mean. I've no idea what FS does when it is doing it.

Perfectly clear, thanks for explaining.

Well, I'm not sure what it is you do not understand, but since the first of the 6 entries is the nearest, and it has its elevation at offset 0x0658 + 12, or 0x0664, and since it is provided in feet as a FLT32, you simply read it with ipc.readFLT(0x0664). What was the problem in understandng this?

Let's say that hex calculus is not my strong point :oops: But with your input I figured it out :idea: All data from 0658 is accessible and readable.

No. I've never seen it happen, unless you are just experiencing the higher levels of turbulence and variance you can get near the surface. If you are seeing that there is none (eg via WeatherSet read-outs), perhaps you should send me the saved FLT and WX files, etc, so I can see what you mean? ZIP and send to petedowson@btconnect.com.

Thanks for pointing me to WeatherSet, made my life much easier (another fabulous tool).

I see an unexpected wild reported variance. Please see attached files: the .doc has WeatherSet screenshots and some brief comments, the .kmz file has the flight path and the locations of each WeatherSet screenshot.

Wherever you see extreme Variances reported in WeatherSet, the in-sim winds are all over the place.

I was under the impression that FSUIPC smoothing would work even if internal FSX interpolation or external weather injection result in wild fluctuation.

PS: I just realized that I cannot attach the .kmz file. I am sending this with email.

Very best regards

weathersetLGAV.doc

[Pete Dowson]

Thanks for pointing me to WeatherSet, made my life much easier (another fabulous tool).

I see an unexpected wild reported variance.

Unexpected? By you?

If there is turbulence set, it will be implemented. You say LGAV METAR was active throught, but even a small distance away from the actual LGAV weather station LAT/LON, there will be interpolation. Are you using AS2012 in DWC mode (its default)? If so, then it is AS2012 which is interpolating. If not it is FSX.

I see you've sent something by email. I won't have a chance to check this til tomorrow. What's a "kmz" file? What can I do with it? I was expecting you to save the Flight so i would be at the same location as you with the same weather.

BTW it is always best to ZIP files as I suggested. They can be more easily placed here then ans well as sent more economically.

Pete

[abax2000]

If there is turbulence set, it will be implemented.

There was no turbulence set, only Variance (see that attached doc with WeatherSet screenshots)

You say LGAV METAR was active throught, but even a small distance away from the actual LGAV weather station LAT/LON, there will be interpolation. Are you using AS2012 in DWC mode (its default)? If so, then it is AS2012 which is interpolating. If not it is FSX.

Yes, DWC in use (forgot to mention that).

I see you've sent something by email. I won't have a chance to check this til tomorrow. What's a "kmz" file? What can I do with it? I was expecting you to save the Flight so i would be at the same location as you with the same weather.

No problem at all; I didn't even expect a reply on a Sunday!

.kmz is a Google Earth file. Just doubleclick it and, if you have GoogleEarth installed, you will see the flight test path. I have depicted the whole test flight there, so you can see the exact geography, distances etc., along with the exact locations where the WeatherSet screensots were taken.

Please see the attached doc file for all other parameters (METAR and how to get it from AS2012 etc).

Location is LGAV rwy03R. Fly the runway heading for appr.9nm, then reverse and align rwy21L (same runway opposite direction). Continue appr 11nm after airport and reverse heading back to rwy03R.

Sorry for any inconvenience.

[Pete Dowson]

There was no turbulence set, only Variance (see that attached doc with WeatherSet screenshots)

And what was wrong? Looking back I see you said

I get wild fluctuations in wind direction (most of the times, and not speed)

which is correct -- that's wind variance. Wasn't it between the extremes set in the parameters you saw?

Yes, DWC in use (forgot to mention that).

Okay, so Active Sky is setting it.

.kmz is a Google Earth file. Just doubleclick it and, if you have GoogleEarth installed, you will see the flight test path. I have depicted the whole test flight there, so you can see the exact geography, distances etc., along with the exact locations where the WeatherSet screensots were taken.

Please see the attached doc file for all other parameters (METAR and how to get it from AS2012 etc).

Location is LGAV rwy03R. Fly the runway heading for appr.9nm, then reverse and align rwy21L (same runway opposite direction). Continue appr 11nm after airport and reverse heading back to rwy03R.

Sorry, I really don't have time for such a test, nor should it be needed. if you still think soimething is wrong, please explain what it is you think is wrong, and save a flight at the very point when the thing you think is wrong is happeninig.

Regards

Pete

[abax2000]

I understand that ActiveSky is setting the parameters, so I am taking the inquiry with them.

The changes in direction are ultra rapid, so the FSUIPC-related question is, if "wind smoothing" set in FSUIPC should prevent changes larger than the setting (Smooth wind changes near aircraft with changes limited to this many knots or degrees per second = 2)

(see attached the Winds page).

[Pete Dowson]

I understand that ActiveSky is setting the parameters, so I am taking the inquiry with them.

The changes in direction are ultra rapid

They can't be "ultrarapid" or you wouldn't be able to see the numbers change. Turbulence is ultra-rapid, wnd variance is a slower up and down change in direction, like gusts are in speed, over the specified range.

...so the FSUIPC-related question is, if "wind smoothing" set in FSUIPC should prevent changes larger than the setting

No! I'm afraid you misunderstand completely! FSUIPC's wind smoothing, if left alone without these added simulations, would prevent all turbulence, all variance and all gusts, because it intercepts the wind values and controls them! That was why I had to then ADD simulation for turbulence, variance and gusts into FSUIPC.

The values it uses to do this were carefully worked out and tested by folks with experience of such effects for real, but if you wish you can change the way they behave using parameters in the INI file -- see the Advanced User's document. Or, if you don't like them at all, you can check the options to turn them off in the Wind options tab. If you want FS's own such simulations then you have to turn FSUIPC's smoothing off, because FS's cannot get through that smoothing control.

Regards

Pete

[abax2000]

What I am saying is that, although "wind smoothing is enabled and set at a value of "2", I have seen:

• wind direction shifts of 60-90degrees per second (as displayed by "shiftZ" lines)
  
• the aircraft (default Cessna) was constantly heading left to right
  

That has happened under the special circumstances documented in previous posts.

With "wind smoothing = 2" I would expect that wind direction shifts would not exceed 2degrees/second (on or about), what is what actually happens under normal conditions, regardless of what AS is injecting or FSX is trying to do by itself.

I again underline that the normal/usual operation of "wind smoothing" is perfectly fine. What I described above is a rare occurrence (under specific conditions), which I cannot explain.

I do understand (thanks to FSUIPC manual) that when FSUIPC "wind smoothing" is enabled, all turbulence, variance and gusts are manipulated by FSUIPC; that is with "wind smoothing" enabled you will get somewhat different results for these attributes compared to std FSX. And that is perfectly fine with me (and a lot of other users).

I sent FLT and WX files zipped as requested.

[Pete Dowson]

What I am saying is that, although "wind smoothing is enabled and set at a value of "2", I have seen:

• wind direction shifts of 60-90degrees per second (as displayed by "shiftZ" lines)
  
• the aircraft (default Cessna) was constantly heading left to right
  

The Cessna is very prone to do that in gusty and variant conditions. You probably wouldn't want to go flying in such conditions. What was the wind variance figure itself?

With "wind smoothing = 2" I would expect that wind direction shifts would not exceed 2degrees/second (on or about)

That will ONLY apply in stable conditions Or if you elect to inhibit the variance and gust simulations (turbulence too if you don't like that). I've explained all this already. Why don't you bother to actually read what I write? It is getting a little tiresome re-explaining things.

I again underline that the normal/usual operation of "wind smoothing" is perfectly fine. What I described above is a rare occurrence (under specific conditions), which I cannot explain.

But you did explain it. WeatherSet confirmed that your wind was subject to variance. You've not bothered to tell me what the amount of that was, but it does seem quite high.

I sent FLT and WX files zipped as requested.

I'm really not intereseted in even looking at those until you confirm that you have read what I have written and understand.

If you do not like the simulation of variance and so on, just switch it off, as i suggested, or play with the parameters which control it in the INI file.

This thread is getting no where and is merely repetitive until you realise what is being said.

Pete

[abax2000]

You at least have to give the courtesy of understanding that in an erratic communication both parties can have a share of responsibility.

Rest assured that I read very carefully what has been written.. If you see that I didn't undesrtand something, you can just explain.

What was the wind variance figure itself?

Variance (as shown in files attached and send) maxed at 300.

That will ONLY apply in stable conditions Or if you elect to inhibit the variance and gust simulations (turbulence too if you don't like that).

This I really don't understand and need some explaining.

What is "stable conditions"? why would you need smoothing in stable conditions?

What I thought, is that "wind smoothing" limits any kind of direction variance, regardless of source (FSX or AS).

You've not bothered to tell me what the amount of that was, but it does seem quite high.

I've bothered enough to send a quite detailed file with all this info attached to #5, which unfortunately seems that was out of specs.

[Pete Dowson]

Rest assured that I read very carefully what has been written.. If you see that I didn't undesrtand something, you can just explain.

But I don't see that. I only see you making the same complaint, the same questions, even after I thought I had answered them. If you don't understand my answers why aren't YOU asking the questions?

Variance (as shown in files attached and send) maxed at 300.

300 degrees? That allows a lot of wild swings in wind direction, which is what you are seeing. This usually only happens at low wind speeds, thank goodness.

The three METARs you showed earlier indicated a variance thus:

LGAT 172226Z 36009KT 310V050

LGMR 172247Z 02009KT 320V080

i.e. 100 degrees and 120 respectively. With a wind speed of 9 knots that's actually quite high. It would certainly make Cessna flying rather hazardous, though it shouldn't affect the heavy metal too much.

This I really don't understand and need some explaining.

What is "stable conditions"? why would you need smoothing in stable conditions?

A wind with no turbulence, no gusting and no variance is what i would call stable. The smoothing is acting on the CHANGE in that wind over time and space. i.e. as the aircraft is flying, climbing or descending it is moving through different weather areas and different wind layers. Without smoothing these changes can act rather too fast, and the smoothing smooths those changes, so that one area and layer blends smoothly into the next.

Turbuence, gusts and variance are effects of the wind at any location irrespective of time and distance. The point, as I tried to explain earlier, is that because of the way FSUIPC has to act to smooth the winds, those three effects which would normally be simulated by FS are completely squashed. Therefore FSUIPC simulates them itself so they are not lost.

What I thought, is that "wind smoothing" limits any kind of direction variance, regardless of source (FSX or AS).

No. Wind variance is an effect like gust and turbulence. Turbulence is fast small changes in all directions, gusts are slower more rhythmic changes in wind speed, and variance is the same but in wind direction. All three effects can be suppressed if you wish -- and, as I've pointed out, FSUIPC's simulation of them can be adjusted via the parameters I pointed you to.

If you'd kindly read back through my previous replies you should see i've been saying these things all along. I really did not see, nor did you ever say, that you thought wind variance was simply the normal varying of the wind with time and distance. It isn't.

Regards

Pete

.

[abax2000]

The smoothing is acting on the CHANGE in that wind over time and space. i.e. as the aircraft is flying, climbing or descending it is moving through different weather areas and different wind layers. Without smoothing these changes can act rather too fast, and the smoothing smooths those changes, so that one area and layer blends smoothly into the next.

That's clear now.