I am very,very very disappointed

[Byrna 0]

A little update to this oscillation issue from my Friday's flight:I flew the 777-200LR from Montreal Pierre-Elliott Trudeau (CYUL) to Frankfurt-Main (EDDF) using Active Sky Graphics version 6 with wind smoothing enabled and some other tweaks in FSUIPC to increase time between wind shifts etc...I used the PSS load editor and got a C.G of 28% and entered it in my CDU.At 16X, the oscillations returned. But at 8X, the plane was stable (with very slight osciallations of +/- 10ft which even happen with no weather/clear weathe). However, at a certain point during the trans-Atlantic crossing, the weather had calmed down and at 16X, the plane was actually stable again. Then, later on, closer to Europe, the weather got cloudy and probably more turbulent and the 16X oscillations were too much once again but 8X was stable.If the 16X instability was due to an incorrect C.G, I think the oscillations would have disappeared after fuel was burned and remained stable - am I right?One question which is probably in the manual but it's good to be sure and ask these things: The C.G % in the LOAD EDITOR - which CG is it? The take-off CG or the cruise CG?Anyways, perhaps the above info will of some help.John

[pilotpm 0]

Hi, :-) sorry didn`t look a long time now at here,I solved the probs ( allmost ) with the tipps fromBob. Using the CG between 14 and 18% for both T7 200 and 300.This did the trick for me .Whit that i can live until the Patch comes up and hopefully she`s stable as a rock then.....I never use a Add On weather engine only the FS one i think thats always the best reason for testing.cheersMario G

[Guest aelstthierry]

Hi guysIt's possible that there's a bug, but be shure you don't pass the forward and aft limit of the CG. The CG position is expressed as a percentage of the mean aerodynamic chord. The CG position affects the stability and the maneuverability of the aircraft and also affects fuel concumption. To have a aft. CG reduces the fuel consumption.The CG calculated on the exel file is the TOW CG, because fuel on board is in the calculation.The best thing is to have load and trim sheet to calculate you TOW CG and ZFW CG. For Airbus planes you need both of them to fill in your FMC.I just both the 772LR and did a flight with it without bumpings.GreetingsThierry

[Guest neiljay6]

Hi there I to am experiencing these strange occillations, but only with the 777-300ER. I tried using bob's remedy and shifted the weights forward so I get a CG value of about 18%. But at altitudes above fl300 I get these terrible oscillations at normal speed. I don

[JW6984 0]

This must just be an issue in the -300. I purchased the -200LR and my flight model is stable. When I turn on 4X acceleration I notice a very small oscillation, but it's not significant. I use the PSS load editor with ZFW = 399,400 lbs and CoG = 27% (MAC). The only problems I've encountered with the PSS777 is with the FMC/CDU which I believe has been acknowledged by PSS, and the sliding tendencies during rollout.

[Guest vcom]

>The only problems I've encountered with the PSS777 is with the>FMC/CDU which I believe has been acknowledged by PSS, and the>sliding tendencies during rollout.More problems here:*AP too much instable and with abrupts reactions in VS/VNAV/HOLD modes. Too far for simulate the real AP in 777.*Airplane slides during rollout in Autoland.*FMC shows various wrong informations.*Reactions flying the T7 without AP (hand flying) strange a little. Roll and pitch atittudes are strange.Ernest.

[Byrna 0]

Hello Thierry,Can you explain a bit what this C.G. percentage represents in terms of feet of distance from the chord or centre of gravity? I don't understand your explanation. Also, where in the FMC do you entre ZFW CG? I just have take-off CG but there is the PERF INIT page where there is a CRUISE CG but I don't know which of them you mean by zero fuel weight versus GTOW (or TOW?) CG?Thanks again.John

[Guest aelstthierry]

Hello JohnFirst of all let me say that I have no data of the B777, only A320.The determination of the CG location is in function of the dry operating mass, pantry adjustments, cargo loads, passengers and fuel on board.What's the difference between ZFW CG and TOW CG.You need ZFW CG to calculate the TOW CG.You have to decrease your ZFW CG with the fuel index to obtain your TOW CG. SO the TOW CG will be always smaller than the ZFW CG.Your CG depends of your weight. So I don't understand the Boeing Cruise CG philosophy (somebody dose?please let me know) because your weight changes during flight, so your CG to. For me the the Cruise CG must be between TOW CG and ZFW CG.I can give you figures for the A320 reference chord is located.The reference chord lenght is 4.193m(13.76ft) and is located 16.31m(53.51ft) after of the aircraft nose. The determinations of those figures I really don't know how they calculate it. For Airbus, were do you fill in those indexes. The ZFWCG is entered before your ZFW on the INIT page. Format: 33.5/66825 (this doesn't work on the PSS software)Your TOWCG is entered with the trim position Format: 31.2/1upFor A320 try to have TOW CG higher then 25%, so you have a aft CG what reduces fuel burn and less pitch down on descends.GreetingsThierry

[Byrna 0]

Thanks Thierry, though I have no oscillation issues with the A320 but the theory is helpful indeed.Thanks again.John