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drdickie

Pitch oscillation at curise altitude with 747

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This has been reported prior to the latest update being released with the hope that it would be solved. However, the pitch oscillation is still present after the update. It is quite to easy to see on my system. The rate-of-climb indicator moves up and down in a regular pattern (sine wave?), and you can see the model moving in spot view. It seems to be pretty much independent of gross weight, altitude, etc. I notice it with both the FS9 and FSX versions.I guess I must have a weak stomach because it actually makes me feel a little nauseous after watching for a while -- I know, don't watch. But, for me, the effect kind of spoils an almost perfect aircraft.Thanks for your continued pursuit of excellence! We all appreciate it.

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I would like to correct a statement I made in the original post. I only observe the oscillation with the FSX version of the 747. On my system, the FS9 version is very stable.Sorry, and thanks.

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Have you ruled-out MSFS WX induced problems? Does it do this with no winds, no weather?

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The pitch oscillation occurs with no wind and "clear skies". The ground speed and true airspeed are the same.

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I am also experiencing this issue with the 747-400X in FSX.I see this pitch oscillation in level flight, but it is most pronounced in the descent phase of flight.Is there any way to eliminate this issue.BTW this happens in clear weather and when I have minor winds and clouds selected.Any ideas?Bingo

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Please sign your name to posts in this forum.If you are experiencing pitch oscillations with no weather, please post a couple of screen shots so we can see what is going on.

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Dan,I'll post screen shots later.As to your comment about "Name." I thought Bingo would be ok as that is my handle.My real name is Bill, so is it OK to use Bingo?Bill

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My real name is Bill, so is it OK to use Bingo?
No. If you read the post pinned near the top of this forum you will see that you are required to sign your posts with your full real name. :( Iain Smith

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No. If you read the post pinned near the top of this forum you will see that you are required to sign your posts with your full real name. :( Iain Smith
OK,Missed the note.....will do!Bill Clark

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I attempted to take a screenshot using "Print Screen" but got an error message.Is there a tool you can recommend that will take multiple shots while flying?Bill Clark

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Are you guys using ASA or ASX or some other weather prog ??? I had the same probs and it was weather relatedRgdsPaul Harvey

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Are you guys using ASA or ASX or some other weather prog ??? I had the same probs and it was weather relatedRgdsPaul Harvey
Paul,No weather programs.......it is set to "Fair Weather" in the FSX weather section.I am looking for a tool tool to take screen shots withBill Clark

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I attempted to take a screenshot using "Print Screen" but got an error message.Is there a tool you can recommend that will take multiple shots while flying?Bill Clark
Pause sim/Press V/image in my pictures/open in paint/save as jpeg/upload to tiny pic

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Hi All,I wanted to point out that I'm not using and 3rd party weather programs nor weather under FSX other than "Clear Skies." My flight is from Puerto Rico TJSJ to St Maartin TNCM.I have flown this several times, so I hope my images convey what is going on. These oscillations occur in CLB, CRZ, and DES, where DES seems to be the most extreme in terms of the swinging back and forth of the PDI indicator as it attempts to predict the where the A/C will arrive at the programmed altitude. The motion is periodic in nature (possibly sinusoidal). The two images below depict the CLB phase of flight (I hope they are not to big or small as this is the first time I have done this on AVSIM):The next image shows the CRZ phase. In this phase the oscillations are really small, but they are detectable visually when looking out the front of the A/C:The DES phase is appears to tbe the worst as the swings are very noticable, but the plane does reach the proper predictated altitudes where they are sup[posed to. Also, note that the EICAS shows CRZ even though the plane is actually in descent.Bill ClarkSorry, Ignore the image below.

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Nothing obviousely wrong jumps out at me.. the first two CLB shots appear normal. In the second one you are below 10,000 climbing at 257KIAS and the first one you have climbed above 10000 and are accelerating to climb speed. I notice you lost a 20kt tail wind so if that happened quickly then adjustments to pitch to control speed are necessary in msfs. It is normal for the green arc to vary during climbs. The descent looks like it is staying on the VNAV profile fairly well, but it is hard to see any difference in pitch that you are complaining about. Again, it is normal for the green banana to vary in VNAV. I notice you are descending to 2900 ft at ULUBA, about 15 nm ahead and the FMS speed but is 242 instead of 240 because of the min clean maneuvering speed at your current weight... I'd recommend first notch of flaps pretty soon to let the speed drop below 240 as you approach the terminal area.Let me ask this: What is the magnitude of the pitch oscillation (degrees) that concerns you? Ignore the green banana, how much is the nose going up and down on the PFD?

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Dan,It is very difficult to communicate this issue via static images when the issue is relative motion.The swings in altitude vary from -2100 to -1500 during the descent phase. The "Green Banana" swings are excessive, in my opinion, given the flight is being carried out in calm weather. For example it swings beyond the targeted way point and then comes way back ahead of it. The climb phase swings are similar to the descent phase in terms of the magnitude of the elevation swings. I still fly the LevelD 767 in FS9 on occasion, and it doesn't exhibit this characteristic, but I'm in the process of migrating to FSX, and I love this rendition of the 747-400X.The best way to communicate this is to send you a video, so maybe I could create a video and mail it to you, or post it on the server of my ISP if I have sufficient space to store a video there? Would FRAPS be the best tool to use? Please let me know what I should do next?Bill Clark

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Dan,It is very difficult to communicate this issue via static images when the issue is relative motion.The swings in altitude vary from -2100 to -1500 during the descent phase. The "Green Banana" swings are excessive, in my opinion, given the flight is being carried out in calm weather. For example it swings beyond the targeted way point and then comes way back ahead of it. The climb phase swings are similar to the descent phase in terms of the magnitude of the elevation swings. I still fly the LevelD 767 in FS9 on occasion, and it doesn't exhibit this characteristic, but I'm in the process of migrating to FSX, and I love this rendition of the 747-400X.The best way to communicate this is to send you a video, so maybe I could create a video and mail it to you, or post it on the server of my ISP if I have sufficient space to store a video there? Would FRAPS be the best tool to use? Please let me know what I should do next?Bill Clark
If the file is less then 100mb try http://drop.io/ Rob

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The swings in altitude vary from -2100 to -1500 during the descent phase. The "Green Banana" swings are excessive, in my opinion, given the flight is being carried out in calm weather. For example it swings beyond the targeted way point and then comes way back ahead of it.
I think you mean the verticle speed varies from -2100 to -1800? That is not a problem, I asked how much the pitch changes. For example in your pics the nose is up about 4-5 deg in both pics in descent where you said there is much variance in pitch... is it only varying one degree or many more? This is how I would define a pitch oscillation.

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Dan,The pitching of the A/C is excessive in my opinion. The numbers I gave you (-2100 to -1800) are the only means I have to quantify this for you in terms of the pitching action.The ADI doesn't show any pitch change at all, but when looking outside the plane, or observing the "Green Banana," it is very evident that plane is pitching up and down continuously at a cyclic rate. I'll see if I can create a video in the next week or so as I'm not very good at articulating this issue.Bill Clark

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Bill-A couple of things come to focus when looking at your images and reading your post.While you do not appear to have downloaded or set any WIND per se, you do have temperature variances taking place in your sim-world. Take a look at the temperature readout on the upper EICAS. You are flying through some extremely odd temperature ranges- and some rather extraordinary temperature inversions. I would expect to see a temperature SIGNIFICANTLY colder than the one you saw at FL200, and the temperature relationship between your climb and descent images is equally odd... So the environment you are flying in is not following even close to the standard adiabatic lapse rate...The result? As the air surrounding the wing changes in temperature, you are going to get different lift results- so the airplane is behaving correctly in this instance by adjusting the rate of descent to meet the VNAV PATH targets as needed. This is why you are using VNAV PATH after all- it is constantly monitoring your descent path and making adjustments to keep the airplane on a geometric PATH so that you arrive at the proper location in space, rather than simply flying you at a set vertical speed and accepting the results.Watching your green altitude intercept ring move around isn't really going to tell you much because it is (correctly) influenced by factoring Even a subtle change in '50/min will rill result in a large position change if you are still high in the descent. In the airplane, you use it to get a general idea that you are "in the neighborhood of your requirements" and for very fine tuning when in close if you are using V/S to manage the vertical component of, say, an NDB approach.One other item to point out- in your climb pics- the reason you might have seen some oscillation is that the airplane was in the acceleration/cleanup phase of flight. This is normal- and you want the airplane adjusting pitch to capture and maintain the target speed. In your images above- the airplane is doing precisely what I'd expect it to do....

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Bill-A couple of things come to focus when looking at your images and reading your post.While you do not appear to have downloaded or set any WIND per se, you do have temperature variances taking place in your sim-world. Take a look at the temperature readout on the upper EICAS. You are flying through some extremely odd temperature ranges- and some rather extraordinary temperature inversions. I would expect to see a temperature SIGNIFICANTLY colder than the one you saw at FL200, and the temperature relationship between your climb and descent images is equally odd... So the environment you are flying in is not following even close to the standard adiabatic lapse rate...The result? As the air surrounding the wing changes in temperature, you are going to get different lift results- so the airplane is behaving correctly in this instance by adjusting the rate of descent to meet the VNAV PATH targets as needed. This is why you are using VNAV PATH after all- it is constantly monitoring your descent path and making adjustments to keep the airplane on a geometric PATH so that you arrive at the proper location in space, rather than simply flying you at a set vertical speed and accepting the results.Watching your green altitude intercept ring move around isn't really going to tell you much because it is (correctly) influenced by factoring Even a subtle change in '50/min will rill result in a large position change if you are still high in the descent. In the airplane, you use it to get a general idea that you are "in the neighborhood of your requirements" and for very fine tuning when in close if you are using V/S to manage the vertical component of, say, an NDB approach.One other item to point out- in your climb pics- the reason you might have seen some oscillation is that the airplane was in the acceleration/cleanup phase of flight. This is normal- and you want the airplane adjusting pitch to capture and maintain the target speed. In your images above- the airplane is doing precisely what I'd expect it to do....
Rob and Dan,Thanks for your quick responses.Now that you mention the "temperature" discrepancies, I did think that they were rather low at cruise altitude, but didn't give much thought to it at the time. So you make an excellent point. Since I have made a concerted effort to move from FS9 to FSX, I'm beginning to notice a lot of funny quirks about FSX not seen before.Given this temperature anomaly is potentially the cause of the 747-400 oscillation behavior, I have some questions:1) Is there anything I can do to the FSX settings to bring these temperatures back into line?2) Has anyone experienced this temperature issue besides me?3) Should I purchase FSUIPC and change some parameters to mitigate this issue.....I have it installed in FS9? 4) I suppose I could try activating real weather in FSX to see what happens?5) I do have one more question, why does the 747 EICAS show the plane in CRZ when it is actually in descent phase?Thanks again,Bill Clark

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Bill-1) Is there anything I can do to the FSX settings to bring these temperatures back into line?I find that the temperature variances are present in both FSX and FS9. They appear in slightly different ways, however. To mitigate them, I generally set weather to "real world static" unless using a 3rd party application such as ActiveSky. Even with a good product like ActiveSky- you'll still see some fluctuations- it's a part of the lifestyle of a sim pilot...2) Has anyone experienced this temperature issue besides me?Plenty of people. You'll find that if you are flying in areas where there are very few weather reporting stations (airports) you can get some very large fluctuations. These changes in the real world would cause the airplane to cease flying or disintegrate due to stress loads- but fortunately nature has some laws that it follows for temperature/pressure changes in a fluid...3) Should I purchase FSUIPC and change some parameters to mitigate this issue.....I have it installed in FS9? Others are probably in a bettter position to answer this question...4) I suppose I could try activating real weather in FSX to see what happens?See my answer to #1 above...5) I do have one more question, why does the 747 EICAS show the plane in CRZ when it is actually in descent phase?The EICAS isn't showing the airplane in CRZ... it is showing your THRUST LIMIT MODE in cruise. This can happen for a multitude of reasons, all of them pilot actions. :-) Without knowing how you managed your FMS, it would be hard to predict- but you can also force the thrust mode in most cases. (Some airlines don't even use CRZ thrust, for example- they force the FMS to remain in CLB thrust because you get better responsiveness and a higher maximum thrust limit, for example...)Hope we could help, Bill- Welcome to advanced simming. :-)

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Bill-1) Is there anything I can do to the FSX settings to bring these temperatures back into line?I find that the temperature variances are present in both FSX and FS9. They appear in slightly different ways, however. To mitigate them, I generally set weather to "real world static" unless using a 3rd party application such as ActiveSky. Even with a good product like ActiveSky- you'll still see some fluctuations- it's a part of the lifestyle of a sim pilot...2) Has anyone experienced this temperature issue besides me?Plenty of people. You'll find that if you are flying in areas where there are very few weather reporting stations (airports) you can get some very large fluctuations. These changes in the real world would cause the airplane to cease flying or disintegrate due to stress loads- but fortunately nature has some laws that it follows for temperature/pressure changes in a fluid...3) Should I purchase FSUIPC and change some parameters to mitigate this issue.....I have it installed in FS9? Others are probably in a bettter position to answer this question...4) I suppose I could try activating real weather in FSX to see what happens?See my answer to #1 above...5) I do have one more question, why does the 747 EICAS show the plane in CRZ when it is actually in descent phase?The EICAS isn't showing the airplane in CRZ... it is showing your THRUST LIMIT MODE in cruise. This can happen for a multitude of reasons, all of them pilot actions. :-) Without knowing how you managed your FMS, it would be hard to predict- but you can also force the thrust mode in most cases. (Some airlines don't even use CRZ thrust, for example- they force the FMS to remain in CLB thrust because you get better responsiveness and a higher maximum thrust limit, for example...)Hope we could help, Bill- Welcome to advanced simming. :-)
Rob,Thanks much!I have a follow-up to my question number 5) as I'm a little confused:If you look at the last two images I posted (Ignore the image at the very bottom - sorry about that as I didn't know how to delete it), I was in the descent phase of flight. However the following information appears appears in the image just above the bottom image: ADI - SPD / LNAV / VNAV PTH EICAS - CRZNote - the only descent image you should be looking at is screenshot number 5 from the top. I started my descent from FL210 and as you can see the altitude is around 7,720 and the descent rate is 2100 ft/min when I took the screenshot, but the EICAS still says CRZ.So my take is that you are referring to the very last image when you mention "Thrust Limit," not the screenshot image above bottom one that actually reflects descent. I just want to clarify that we are looking at the same image? I apologize since I didn't do a great job of labeling my images.Thanks again for your assistance,Bill Clark

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Time to refer to the AOM, see Aircraft Systems pg 11-29 you'll find thrust mode annuciation. Note there is no descent thrust limit. The CRZ limit will apply during descent until a go-around is active.

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