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B777 Fuel flow factor


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Hello all,

 

At work, the operation department publishes a Correction Factor & Performance Factor (Drag/FF) for the B777 fleet twice a year.  The Correction Factor is used for fuel planning while the Performance Factor (Drag/FF) is used for FMC. In essence, they both match to ensure the flight plan and FMS are using the correct Drag/FF data. One of the B777 I am using has a correction factor as (-0.7) in which, when looking at the IDENT page in the FMS of the real aircraft, it shows as (Drag/FF = 0.0/-0.7 >>> which I also got it to show in the PMDG FMS as well). In the flight plan from work when using the particular aircraft registration I chose, it also displays that info as well. 

 

So my question is, having a Correction factor of -0.7, how can I implement that in PFPX so that PFPX is calculating the correct fuel burn? I hope I made sense in what I am trying to say.

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Would these entries not equate to the Drag Bias and Cruise Fuel Bias entries of PFPX in the aircraft configuration equaling the correction factor.

 

I'm not sure that you could get the PFPX and FMS entries to match however as the data is unlikely to match at the outset. Does the PMDG even act on these figures.

 

Using the Aircraft Performance Monitor application within PFPX should allow the planner to get a close match of the fuel calculation to that of the aircraft.

 

Fuel bias is indicated in the standard PFPX OFP and drag entry could be added with <&DragBias>

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21 hours ago, srcooke said:

Would these entries not equate to the Drag Bias and Cruise Fuel Bias entries of PFPX in the aircraft configuration equaling the correction factor.

 

I'm not sure that you could get the PFPX and FMS entries to match however as the data is unlikely to match at the outset. Does the PMDG even act on these figures.

 

Using the Aircraft Performance Monitor application within PFPX should allow the planner to get a close match of the fuel calculation to that of the aircraft.

 

Fuel bias is indicated in the standard PFPX OFP and drag entry could be added with <&DragBias>

 

1). I think the Cruise Fuel bias would be the Correction Factor (or Fuel Flow Factor) number after consulting with a friend who is a flight dispatcher.

 

2). I don't think PMDG reacts to the DRAG/FF figures. Although, it does look cool when I see it in the IDENT page (as per attach screenshot). A for in PFPX, not sure if it calculates the Cruise Fuel bias.

B777 IDENT.jpg

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Indeed a cool find in that the function to enter the data indeed works.

 

It is a shame that the entry does not save to the airframe .ini file so that it reloads on next sim start, or have you found a way around that ?

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The function to input the DRAG/FF value directly in the IDENT page of FMS, I don't think PMDG simulate that or it doesn't allow you. I tried a few times but it didn't work me or at least I was doing it wrong and that is why it didn't work me. Anyway, below is what I did (even did it when I had PMDG in FSX years ago) and I'm sure it will work for everyone if you follow the steps below. Remember, the DRAG/FF values are different for each aircraft registration and the only way I obtained them was from work. I don't know if there is a website where you can look them up to obtain the DRAG/FF values, although it would be nice and if 1 was to exist, how accurate would it be? Because I have a couple of ANA B777 installed and United B777 installed, I just use same the DRAG/FF value of ANA (i.e JA795A)with the United ones (i.e N2352U) because clearly, I don't work for United.

 

1). Find the Aircraft.ini file, for example, you can find it:  C:\Program Files\Lockheed Martin\Prepar3D v4\PMDG\PMDG 777X\Aircraft

 

2). In that folder, you should have .ini file for each registration aircraft you have installed. For example, for me, I have JA789A.ini, JA795A.ini, N2352U.ini

 

3). Take JA795A.ini for example. Open up the .ini file and stroll down until you find the [FMS] section and underneath that, look down until you find the DragCorrection and FFCorrection. For me, because there is no value available for the DragCorrection, I leave it as 0 (zero). As for the FFCorrection, that's where you input whatever value you have like for me for example, the FFCorrection value for JA795A (again I got it from work) is -0.7, so I type -0.7 in the FFCorrection to read as FFCorrection=-0.7

 

Now, each time I run P3D and select JA795A for example, when you look at the IDENT page, you will always see the values in the DRAG/FF section in the FMS. Again, does PMDG reaction to those numbers to give proper fuel burn when the engines are running? I don't know. But at least every time you select a PMDG 777 aircraft and look at the IDENT page, you can see the DRAG/FF values just like in the real aircraft. So for PMDG other aircrafts, (i.e. B737), I'm not sure how/where to input the DRAG/FF values. It'll probably be the same steps as outlined above. 

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It is confirmed by PMDG that the drag & fuel correction factors are for information only.

 

The data displayed on the IDENT page can only be retained if entered as posted by raptor84 above should you wish to add the PFPX figures for reference.

 

 

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4 hours ago, srcooke said:

It is confirmed by PMDG that the drag & fuel correction factors are for information only.

Yes, I would assume so. Although, it would be nice if PMDG did simulate the drag & fuel correction.

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