747-400F Polar Air Cargo after update... MTOW/GW

[Captain Kevin 586]

Yes, I am aware of what he said. I wasn't aware that you were trying to fly this at maximum payload regardless.

[BlueStar 323]

20 hours ago, Jetlinker said:

If it’s of any help I can confirm with 100% certainty that the real world aircraft in question has the 875,000 (396893kg) MTOW. 

5Y? 🙂

 

[BlueStar 323]

14 hours ago, ahuimanu said:

Thanks Kevin,

 

If you look at Michael's response to me, there were changes from the pre -8F and post -8F versions of the 747-400 base.  The changes are actually a reduction from the previous max weights.  The increased weight meant that I could fly further with a full load.

 

Hi Jeff,

I haven't noticed any problems using PFPX, but I only fly routes that I am familiar with.  The longest I fly is ANC-HKG up on R220.  Again like all freighter flights I'm familiar with MZFW and MGLW are almost always the limiting factors for me, especially MGLW. 🙂

Grace and Peace, 

[ahuimanu 50]

Thanks.

 

The pre-update 747-400F and PFPX aligned almost perfectly.  Since the update, not so.  I suppose my issue is to develop a better PFPX profile.

[Captain Kevin 586]

If you pick a profile on PFPX, you'll have to mess with the fuel and drag bias for better results. If you run the simulator, pick an altitude and speed, and there's a window that requires you to enter gross weight, altitude, ground speed, true airspeed, static air temperature, and I think a few other things. Enter that information in, and it'll figure it out on its own. Best to do this with no weather.

[skelsey 765]

On 11/22/2018 at 2:23 AM, ahuimanu said:

Thanks Kevin,

 

If you look at Michael's response to me, there were changes from the pre -8F and post -8F versions of the 747-400 base.  The changes are actually a reduction from the previous max weights.  The increased weight meant that I could fly further with a full load.

 

The MTOW figure is not always structural and this particular value definitely is not. Airlines often artificially 'write down' the MTOW figures to save on landing and air traffic control charges (which are based on the certified MTOW) - if they only fly short routes that never need the extra weight, the easy solution is to get Boeing to certify the aircraft with a lower MTOW.

Nothing changes structurally - same engines, same airframe, same landing gear etc. It's just a paperwork exercise - and so it is in PMDG's case also. 

If you know that a particular airframe has an MTOW greater than the figure provided in the PMDG information (as Jetlinker says) go ahead and use it. No need to change anything in the aircraft.cfg. Provided you load the aircraft so that the CG is within limits and the actual certified MTOW of the airframe isn't exceeded, the wings won't fall off and the aircraft won't fall out of the sky - it'll behave just like a 747 would at whatever weight you have loaded it to...

[ahuimanu 50]

Thank you Simon and Kevin,

I suppose my real issue is that the change broke some harmony between the PFPX profile and my planning routine.  Perhaps the new PMDG product will allow us these variances between aircraft.  I will use the suggestions provided to improve my PFPX utility.

[Captain Kevin 586]

What I suggested will adjust the numbers to the PFPX profile, so to speak.