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Actual weights to be used for PMDG 738 NGX


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Hello.

First of all I would like to say that as far as I've tinkered with PFPX, its amazing. Now my question is what weights should I use for PMDG 737-800 winglets model. Default weights in PFPX and ones in PMDG FCOM seem to vary a bit, especially max take off weight, some 9 tons.

If anyone have accurate weights to be used I would be most grateful.

Kind regards,

Raimo

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After some reading PMDGs own mauals and checking official weights of NG, Im even more confused. I think Im just going to do some flights and figure it out. Suggestions and figures are most welcome ofcourse.

Kind regards,

Raimo

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Hello.

I used the weights from the PMDG manual, but also think that the MTOW is wrong in their manual (something around 70.000 kgs).

For the 737-800 it should be something around 78.000 to 79.000 kgs. Thats also a value I remember when I used to do loadplanning and loadsheets for the 737 series ;)

I also did not check what weight PMDG uses per Pax when you use the FMC to load your plane. For PFPX its either 84 kgs (schedule) or 76 kgs (charter).

Would be nice if there would be a possibility to produce a printable loadsheet for the PMDG NGX. Anyone seen such a tool?

Thanks & bye


Jan


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Hello,

These values are indeed confusing.

As you load the 737-800W version in FSX, in the FMC you can see the ;

MTOW = 79.200 kg

ZFW = 55.200 kg (this depends on the payload of the aircraft. FSX has default pax at 92 and cargo forward and after at 3266 kg. So If you reduce your payload, the ZFW also reduces)

max FUEL = 20.891 kg

max Cargo = 10.150 kg

So for example ;

If you enter 0 fuel, 0 cargo and 0 pax, the empty weight = 41.400 kg.

If you enter 174 pax, forward and aft cargo 3750, you have a load level of 100%. MZFW = 62.700 kg. (during the flight this remains constant)

If you start entering fuel at this load level, you can enter a max of 16.500 kg until reaching your MTW of 79.200 kg.

Hopefully this helps a bit, for so far my calculation is right.

( If someone else has a different vision, feel free to correct me ).

Regards,

Ardjoen

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Hi,

The aircraft cfg file gives an empty weigh value of 91 300 lbs for the 738W which converts into 41 413 kg

It's quite important to get that value right or your ZFW, TOW and LDW calculations and therefore the estimated underload in regards to your MTOW or MLW (whichever is the limit) will be inaccurate.

It would seem that the FMS in the NGX approximates the weight values like so :

41 413 kg = 41.4 t

41 449 kg = 41.4 t

41 450 kg = 41.5 t

Try loading the 737-800W and setting both the fuel and the payload to 0.

Now add 36kg to the payload (whichever compartment), the ZFW still reads 41.4 t.

Replace the 36kg by 37 kg and here you go, the ZFW has increased to 41.5

The PMDG weight per pax is around 80kg and does not take into account the variations between children and adults as PFPX or TOPCAT do.

Therefore, if you plan a payload of 150 adults and 8 children with PFPX and load it up in the NGX as 158 pax, there might be a small difference in the ZFW. Infants on the other hand don't take any seats and don't add up any weight in PFPX or TOPCAT so you can always add them to your payload :).

To have the exact same ZFW, an adjustment of the adult pax average weight would be needed on PFPX and TOPCAT (80 kg instead of 84).

After further fiddling with the FMS, it appears that the exact pax weight value is not 80kg but a little less. Since I was not able to find the exact value in the cfg files, I proceeded like so :

I start by emptying fuel and payload. I then add 37 kg to one of the payload compartments so as to have a ZFW of 41.5 t (which should be 41 450 actual if the above is right).

I add 100 passengers, if they were really 80 kg each, the ZFW should read 49.5 but it doesn't, the weight per pax is therefore less than 80.

The question is : how much do I need to add to get the ZFW to read 49.5 ? The answer is 62 kg which gives me a weight per pax of 79.38 kg.

Why such a value ? go figure !

Hope this helps !

Any correction for these values if they are wrong is welcome !

Jean-Charles

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