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ahaka

Still not able to maintain heading/wings level in turbulence (747 FSX)

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Hello,Despite the update that was just released, when flying in turbulent weather the 747 tips from one side to another. The autopilot cant keep the wings level or the heading/LNAV track.I'm using FSUIPC wind smoothing, and the FSUIPC turbulence settings are all normal which should work with all airplanes. And so it does, just that the 747X seems to be very unstable.Any solution to this problem as I cant really fly this plane if it starts banking toward 90 degrees soon after takeoff. My balance/load is all normal and within limits?

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Antti:It is quite normal for the airframe to respond to turbulence, and that there is a small lag in the corrections as the autopilot strives to maintain flight path. The forces of nature have no man-made rival and despite her size, she is a spec in the ocean of air currents. The 90 degree bank, I cannot explain- but some heaving and rocking is quite normal/acceptable.Best-Carl F. Avari-Cooper BAW0225http://online.vatsimindicators.net/980091/523.png| XP Pro SP3 | 2 x APC UPS | Coolermaster Stacker 830 SE | Gigabyte P35 DS3R | e8500 @ 4gHz | Tuniq Tower 120 | EVGA 8800GT 512MB | Creative X-Fi Fatal1ty | 2 x 1 GB Corsair XMS2 | 2 x 320GB WD Caviar RAID 0 | Corsair HX620W PS | CH Products Yoke-Pedals-Throttle Quadrant | Aerosoft 747MCP-EFIS-EICAS |

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Hello Carl,I know what you mean and I also know its normal to have some shaking and banking in turbulence.However what I'm talking about is that the plane suddenly banks to the left/right over 60 degrees and starts crashing down and the autopilot doesnt do anything. And this ONLY happens in turbulence. This is a really serious problem for me now as the patch didnt correct it either.

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I expect you are experiencing something different from most of us. FSUIPC's ability to smooth the air is extraordinary.. I use 1 kt/deg change per 3 sec.. and the wings don't even rock... and there is a difference between "turbulence" and wind smoothing, which is intended to fix the MSFS swings.I note that the upset went from 90 to 60 deg... maybe we can help if you can provide us a little more info... such as flight regime (is it immediately after wheels up or climb or cruise), what is you weather source (ASX or default), what is the aircraft configuration (wt, speed, etc). The reason I think additional info would help is because you are experiencing something most of us don't, and we need to try to understand the problem.

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My initial thought...TRIM??Steve Bell

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>I expect you are experiencing something different from most>of us. FSUIPC's ability to smooth the air is extraordinary.. I>use 1 kt/deg change per 3 sec.. and the wings don't even>rock... and there is a difference between "turbulence" and>wind smoothing, which is intended to fix the MSFS swings.>>I note that the upset went from 90 to 60 deg... maybe we can>help if you can provide us a little more info... such as>flight regime (is it immediately after wheels up or climb or>cruise), what is you weather source (ASX or default), what is>the aircraft configuration (wt, speed, etc). The reason I>think additional info would help is because you are>experiencing something most of us don't, and we need to try to>understand the problem.>FSUIPC wind smoothing works great, but when using it, the FSUIPC applies its own turbulence emulation into FSX. Seems like the 747-400 FSX cant fly through the turbulence emulated by it.I'm using ASX, but the problem seems to occur even when settings the weather manually and adding turbulence.For information, the problem occurs at the point the airplane flies into turbulence, whether its right after takeoff or later on. So it really seems to be only caused by turbulence.

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Antti-If you are seeing such extreme behavior from the airplane, then this would indicate to me that you have your turbulence settings unrealistically high, and/or you have extraordinary wind shifts taking place. Keeping in mind that we have modeled the Cl/Cd curve on this airplane to a degree of precision that isn't normally used for FS aircraft- and as such it will "over-react" to unrealistic conditions.(Massive temperature changes and wind direction/velocity changes are not entirely uncommon in FS if you don't "manage" the weather properly...)It has been our experience that the turbulence model in FS9/FSX is really poor- and we are only just now starting to see applications that can reduce the effects of massive and sudden wind shifts and temperature changes.I haven't used FSUIPC's new wind smoothing, so I cannot comment on it- but I do know that Dr. Vaos provided quite a bit of insight to Pete Dowson as he was working on this capability a few months ago.At any rate- if you are seeing 60-90 degree bank angle changes happening suddenly- I would bet the house that if you watch the wind vector on the nav display- you'll see significant and massive changes. You will find that by getting your weather input better managed- that the airplane settles in and handles effectively.

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Robert,Thank you for the reply and insight.I believe it has to do with the rapid wind speed change that FSUIPC turbulence is creating. The shift itself is no more than 3-5 degrees, but its very quick. I dont know exactly what the Cl/Cd curve is, but it makes sense of what you said since it only happens with the 747 and not other FS addon or default aircraft.The funny thing is I dont remember this happened when I was still using FSUIPC 4.26 (though Im not sure if I flew in any turbulence those times). Could there be something in the version 4.28 thats not compatible with the 747.. If no one else is having any problem like this though, I guess its just something mysteriously wrong with my setup..

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To be honest, the best that MSFS can do with turbulence is a very bad imitation IMHO, and I've been in plenty of it in the last 30 yrs, just never in a heavy jet. I never turn it on.Pete has some insights on how to set up turbulence for PMDG using FSUIPC in his forum...it seemed to be a topic du jour for several weeks.CL/CD is probably a ratio of coefficients of lift verses coefficients of drag. This is an important number in simulating aerodynamic behavior of a wing. A concise simulation of turbulence would involve nasty differential equations with inerta, accelerations and the CL/CD rates of change in that area of the lift/drag curve. This is obviously not done in MSFS. This is my guess, I'm an engineer but not a code-smith.

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>The funny thing is I dont remember this happened when I was>still using FSUIPC 4.26 (though Im not sure if I flew in any>turbulence those times). Could there be something in the>version 4.28 thats not compatible with the 747.. If no one>else is having any problem like this though, I guess its just>something mysteriously wrong with my setup..I just upgraded to 4.28 from 4.26 last night. I'll be flying on VATSIM FNO tonight, and will report here if I notice any odd behavior. But, for certain, 4.26 wind smoothing has been rock solid for me since its release.- Bill

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Yeah the thing is, real life turbulence is not sudden and massive changes in wind speed and direction like what happens in FS - that's probably more accuratly called windshear.

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Finished my flight on VATSIM, and can report that the wind smoothing seemed to work the same for me while using 4.28 (i.e. same as 4.26). I must admit, I didn't have much turbulence in the flight. I'll perform a couple of experiments with artificially high turbulence }( to see how she behaves. Will let you know.- Bill

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Thanks for the info Bill!In case you wont experience any of the weird behavior, could you post your FSUIPC4.INI file here? And are you flying with ASX and which service pack are you using?

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Done some further testing...Disabling the FSUIPC turbulence seems to help, but then of course there wont be any turbulence in flights.The most extreme bank angles (60*+) seemed to occur in cloud turbulence. (At least for my test flight)What I know is that in 4.28version of FSUIPC the vertical air was enabled again. Could this have caused these problems? Perhaps I'll have to post in Pete Dowsons forum about this.

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If you are using a weather package that communicates via FSUIPC it could be changing those settings when you state your preferences in it.Notice there is a separate setting for turbulence in clouds (on/off) or turbulence in CB.In FS9 in its FS9.cfg there is an overall turbulence scaler as:TurbulenceScale=0.300000under the WEATHER section. I use .3 for a more realistic setting. Default is 1.0. The average recommended by some other users is 0.4.Perhaps in FSX there is a similar setting in its .cfg file.

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So, I flew another flight with the turbulence set to "severe". No problems. Here is the "General" section from my FSUIPI.INI:[PRE]ShortAircraftNameOk=SubstringTCASid=FlightTCASrange=40AxisCalibration=NoDirectAxesToCalibs=NoShowMultilineWindow=YesSuppressSingleline=NoSuppressMultilineFS=NoAxisIntercepts=NoWeatherReadFactor=1SimConnectStallTime=1GraduatedVisibility=NoLowerVisAltitude=0UpperVisAltitude=0UpperVisibility=0MinimumVisibility=0MaximumVisibilityFewClouds=0MaximumVisibility=0MaximumVisibilityOvercast=0MaximumVisibilityRainy=0SetVisUpperAlt=NoVisUpperAltLimit=0ExtendMetarMaxVis=NoOneCloudLayer=NoCloudTurbulence=NoCloudIcing=YesGenerateCirrus=YesSuppressCloudTurbulence=NoMaxIce=-4MinIce=-4UpperWindGusts=NoSuppressWindTurbulence=NoWindTurbulence=NoSuppressAllGusts=NoMaxSurfaceWind=0WindLimitLevel=200WindDiscardLevel=400WindAjustAltitude=NoWindAjustAltitudeBy=2000WindSmoothing=YesWindSmoothness=-2WindSmoothAirborneOnly=NoDisconnTrimForAP=NoZeroElevForAPAlt=NoThrottleSyncAll=NoWhiteMessages=NoShowPMcontrols=NoSpoilerIncrement=512MagicBattery=NoRudderSpikeRemoval=NoElevatorSpikeRemoval=NoAileronSpikeRemoval=NoReversedElevatorTrim=NoClockSync=YesClockSyncMins=5ClearWeatherDynamics=NoOwnWeatherChanges=YesTimeForSelect=4LoadFlightMenu=NoLoadPlanMenu=NoPauseAfterCrash=NoZapSound=fireworkShortAircraftNameOk=NoFixControlAccel=NoPressureSmoothness=20TemperatureSmoothness=100SuppressWindVariance=NoTurbulenceRate=1.0,5.0TurbulenceDivisor=20,20,40,40MouseWheelTrim=NoVisibilityOptions=NoWeatherRewriteSeconds=1MouseWheelTrimSpeed=1FixMachSpeedBug=No[/PRE]- Bill

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Hi AnttiIf your using ASX I believe Ryan, as usual, has hit the nail on the head.After playing around with 100's of different ASX settings I think I got it sorted. Try setting your windshear values lower. It worked for me.For some reason ASX looks at these violent aloft changes as windshear.RegardsSteve

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