The Ultimate PSS 777 FDE Tweak

[twasono 3]

Hi All,I am quite overwhelming by the fuel burn rate of 777 series, because of the lack of information about this in the internet and people usualy make the answer without proper official sources.But, at last I've found this important information from other forum (http://www(dot)airliners(dot)net/aviation-forums/tech_ops/read.main/278677)

a CX 777-300ER burns an average of 8100kg an hour (6,500 to 10,500kg across the flight).Some EK Fleet Ops folks provided trip fuel weights for flights on 10 April 2008:777-300ER DXB-JFK: 109t (Flight Time: 13h30m)777-200LR GRU-DXB: 102t (Flight Time: 13h45m)

From above post, we can calculate and assume that the fuel burn rate of each these models:- 777-300ER --> about 8,100 kg/hour- 777-200LR --> about 7,500 kg/hourAnd now, how about another models?For 777-300, I've also found this information from wikipedia

Following flight testing, the implementation of engine, wing, and weight modifications produced an added 1.4 percent reduction in fuel consumption

Well, now I can calculate that -300 fuel burn rate is approximately about 8250 kg/hour, which mean that -300ER should have more efficient fuel burn than -300 at the same conditions (weight, altitude, speed).Using the same assumption as the -300 & -200ER above, the -200LR fuel consumption is more efficient than -200ER by 1.4 percent. (It's only my rough assumption)Thus, I can calculate the -200ER fuel burn rate is approximately about 7650 kg/hourHow about -200? I haven't found any information yet. But again, using assumption, the fuel burn rate of -200 is approximately at 7800 kg/hourFinally, I tried to tweak the fuel_flow_scalar in the aircraft.cfg file to at least produce the nearest results.First, I am doing the tests for -300ER and -200LR using the following conditions:- Weight: set the fuel to 60%- Cruising Altitude: FL350- Cruising Speed: Mach 0.84Then for other models, I just adjusted the fuel % so the gross weight should be similar to either -300ER (for -300) or -200LR (for -200 & -200ER).

fuel_flow_scalar values:- [b]777-300ER[/b] --> 1.110- [b]777-300[/b] --> 1.150- [b]777-200LR[/b] --> 1.090- [b]777-200ER[/b] --> 1.070- [b]777-200[/b] --> 1.140

Please feel free to critize if my assumptions are not correct.Best Regards.Tri Wasono

[Guest fred777W]

hi guys,something else regarding posky 777, is there a way to set the N1 level to correct % at idle. i noticed that for posky at idle N1 at 17.5%. In real 777 the N1 is at 22.5% - 22.7%.i think is a good one to fix as well.rdgsFred

[Jack 0]

Here is some tables from the 777-219 FCOM, we have Trents so we use EPR instead of N1 but might be usful to sombody here to correct the fuel flow. I found 1.28 the best fuel flow over all to use on long haul flights I have done to LAX PEK and NRT over the last month or so. Tables are for 1. Cost Index 50 and 2. LRC which dosnt seen to be active in the PSS FMC

[Jack 0]

@ the guy who asked about the editor being used: I have just been using Aired to modify the Air file and notepad for the cfg, tryed to edit a option like "Corrected fuel flow for N1 or N2 or somthing" didnt get any results from changing it.@ the guy who asked about "Upstick": when you enter you weights into the FMC you will see you have REF speeds that you hard select, speeds that are given from the EFBs are always different depending on loads, rwy condition, wind, weight, SID requirerments, rwy length etc. But if I have found that if you take the FMC REF speeds given for Vr N2 and add 10kts it works pretty well.So if your speeds given by the FMC for example are:Vr - 145V2- 150Set it asVr-155V2-160

[twasono 3]

Here is some tables from the 777-219 FCOM, we have Trents so we use EPR instead of N1 but might be usful to sombody here to correct the fuel flow. I found 1.28 the best fuel flow over all to use on long haul flights I have done to LAX PEK and NRT over the last month or so. Tables are for 1. Cost Index 50 and 2. LRC which dosnt seen to be active in the PSS FMC

Hi Jack,Very good source. Do you have the same table for all other variants?I'll try to adjust and find the correct fuel flow. Thanks.Best Regards.

[Jack 0]

That is for the 200ER with Trent 895s, will have the info for the 300ER shortly, I believe the 300ER only comes with the GE90-115 variant but not sure.... PSS FMCs cost index is also not modelled well. We always use CI 50, in real life the cruse speed will verify with different factors but with the PSS FMC selecting a CI 50 cruse speed always remains the same. Here is the real info on the CI.Twsono, Could you PM me your email address, I have made a lot of changes for the 200ER to get a lot of other items corrected but I cant seem to upload them here. Will seed it to you if you want it.

[kantk2008 2]

edit: nvm, got it to download. I will do a test flight today :)

[FlyCathay 18]

Anyone has problem with flare using this FDE?Dunno why my plane always bounces when it touches the ground.

[kantk2008 2]

So I finally got around to doing a POSKY 777-200ER EGLL-VIDP flight using this tweak and the verdict is....WOW! Amazing work done, I can safely us 16x acceleration with no more oscillating! After tweaking the fuel flow scalars to the values posted in the first post on this page, it looks pretty accurate too. The turns were smooth and although there was still left and right rocking with the plane fighting to stay on the glideslope, it was barely noticeable.That said, there are 2, somewhat major, bugs.1.Randomly, my plane starts spazzing left and right, like one second it's turning right, the next second left. It does this maybe for 4-5 seconds then sorts itself out. This seems to only happen during climb, cruise and decent, not during approach.2.The autoland, although the touchdown is much smoother, the plane's nose stays in the air, like the rear wheels touch the ground, but the nose of the plane is up and the front wheel is off the ground. It stays like this until the plane slows down. This, hopefully can be fixed.Overall, a great tweak to the PSS 777. Very well done!

[twasono 3]

Hi kantk2008,Thanks for the kind words. :)

1.Randomly, my plane starts spazzing left and right, like one second it's turning right, the next second left. It does this maybe for 4-5 seconds then sorts itself out. This seems to only happen during climb, cruise and decent, not during approach.

I haven't met the condition aboveDid you use time acceleration? What motion is it? roll or yaw?It might be your "AP_control_coeffs.dat" file has been changed. It is in "FS9\PSS\BOEING777" folder.Just follow the following values from my folder:

RollOnAilACC=3.4RollOnAilDECEL=3.4RollOnAilINPUTSTEP=2800RollOnAilMININPUT=1000RollOnAilMAXINPUT=31000PitchOnElevatorACC=1.3PitchOnElevatorDECEL=2.3PitchOnElevatorINPUTSTEP=50PitchOnElevatorMININPUT=-12384PitchOnElevatorMAXINPUT=14384VSonPitchACC=400VSonPitchDECEL=1000VSonPitchINPUTSTEP=0.9VSonPitchMININPUT=-15VSonPitchMAXINPUT=30SpeedOnElevatorMaxAcc=2SpeedOnElevatorDecArea=20

2.The autoland, although the touchdown is much smoother, the plane's nose stays in the air, like the rear wheels touch the ground, but the nose of the plane is up and the front wheel is off the ground. It stays like this until the plane slows down. This, hopefully can be fixed.

Could you provide a picture (screenshot) about what happened?I suspect it is related to the Posky panel merge files.Best Regards.

[Richard99_Photography 2]

Hi, I tested yesterday this merge and need to understand something about it (B772ER).First: as reported by posky readme file rudder control is locked above 1 to 60 knots. Is it real? Other aircraft I fly (PMDG 737NG, PMDG 747 and so) as well as the original PSS777 have the rudder working above 1 kt. So when I turn right/left on the ground the rudder remains blocked. Very strange and probably not real.Second: I noticed a very high vertical speed at the begin of descent with the VNAV engaged (more than 5000 ft/min), so I disengaged it and press LV CHG button. Very strange. Did you experience anything like that?Third: I used the GE-90 engine. How should I configure the Aircraft.cfg file correctly? Should I modify the .air file?Thanks. Bye.

[twasono 3]

Hi Rick,

First: as reported by posky readme file rudder control is locked above 1 to 60 knots. Is it real? Other aircraft I fly (PMDG 737NG, PMDG 747 and so) as well as the original PSS777 have the rudder working above 1 kt. So when I turn right/left on the ground the rudder remains blocked. Very strange and probably not real.

This is the limitation within FS, which has no tiller. So, for turning the nose wheel on the ground, it uses rudder axis control instead.

Second: I noticed a very high vertical speed at the begin of descent with the VNAV engaged (more than 5000 ft/min), so I disengaged it and press LV CHG button. Very strange. Did you experience anything like that?

This is a bug on PSS panel because the T/D point is very late, which cause the plane to chase the descent path on extreme V/S. But after VNAV captured the descent path, it should be OK. I always use the V/S mode during initial descend, and then switch to VNAV after the path captured.

Third: I used the GE-90 engine. How should I configure the Aircraft.cfg file correctly? Should I modify the .air file?

For different engine thrust, you can modify the "static_thrust" in the "aircraft.cfg" file.If you know what you are doing, you may modify the .air file. Instead, just leave as it is. :)Best Regards.

[Richard99_Photography 2]

Hi Rick,This is the limitation within FS, which has no tiller. So, for turning the nose wheel on the ground, it uses rudder axis control instead.

Hi, I know that, but my problem is this, I try to describe better. I set up the Z axis of my Saitek x52 for rudder control. Well, with any kind of payware aircraft when rotate Z axis to the left and right I can move left/right the rudder and the nose wheel as well. I cannot with the Posky model cause it was designed for not moving the rudder above 1 to 60 kts. For me it is not real because all aircrafts on the ground when turning left / right have also the rudder moving left / right. Do you agree? Or the behaivou on my payware addons (PMDG 737NG, Level-D 767, PMDG 747) is not modeled correctly? Looks for example at this video:

Pilot flying uses rudder control to correct the aircraft heading on the ground.

This is a bug on PSS panel because the T/D point is very late, which cause the plane to chase the descent path on extreme V/S. But after VNAV captured the descent path, it should be OK. I always use the V/S mode during initial descend, and then switch to VNAV after the path captured.

Ok, I had this effect also with the PSS777 original indeed. So next time I will use initially the V/S mode.Thanks bye.

[Nandan Patel 10]

Rick99 try this one, it's the one I use:http://www.megaupload.com/?d=62JL1FHXYou might have to update your xml files in the POSKY777 folder in the panel folder: http://www.projectopensky.com/index.php?app=downloads&showcat=74

[twasono 3]

For me it is not real because all aircrafts on the ground when turning left / right have also the rudder moving left / right. Do you agree?

In real world, The nose wheel and rudder are moved by different controls. Nose wheel is moved by tiller and rudder by rudder pedal.In FS, both are controled using Z-axis.Mostly, rudder is used to make a heading correction when the plane is in high speed rolling. That's why the FS developers design the function of Z-axis like that. CMIIW.Best Regards.