*Update 15 Mar 22* PFPX Files & Aircraft Model Files for PSX NG FMC Upgrade

[asboyd]

Thank you Steve....

PS. All working now

Cheers,
AlexB

[G-CIVA]

I think there may be an issue with the US flag (jet) fuel policy for PFPX. It doesn't seem to calculate the 10% enroute reserve.

That Fuel Policy is a default PFPX file which I have not edited.

[G-CIVA]

New update as of 08 May 21.

China Airlines PSX Model Files updated to reflect PSX Simulator update 10.135.

Other Airline Fleet files to follow where applicable.

[G-CIVA]

See first post.

Small update as of 17 June 2021.

[beat578]

Thank you steve for your continous support of all those files.

[Steve Hose]

Thank you Steve for the continued updates!

Regards, Steve.

[G-CIVA]

New updates as of 30 Aug 21....see the original post for further details.

[Will]

Thanks for all your work on this project, Steve.

I'm interested in playing around with some PW4062 ERF models. Do you know any tail numbers or operators off the top of your head who use that combination? I'm not asking for an exhaustive list, just a small number to take a look at if possible.

Thanks.

[andrej]

Will,

Cathay Pacific and Korean Air Cargo should have PW4062 ERFs. I am happy to be corrected.

Best,

[Will]

Thanks, andrej!

[G-CIVA]

Steve.

I'm interested in Do you know any tail numbers or operators off the top of your head who use that combination? I'm not asking for an exhaustive list, just a small number to take a look at if possible.

Off the top of my head ....

CPA
KAL
GTI - 2 Ex KAL airframes
ASL - 2 Ex KAL airframes

GTI have one ex UAL 4056 PAX model, one Ex SIA 4056 Freighter & one ex SIA/CPA 4056 BCF.

CKS have taken delivery of a fair number of Ex KAL 4056 engined Freighters & also a have a couple of 4056 BCFs too.

[Will]

Steve, thanks again for all your efforts.

I'm wondering if you can tell me just in broad strokes what kinds of differences you see between performance in the passenger and freighter versions, when weight, engines, and everything else are kept equal. I'd suppose the only differences (please correct me if I'm wrong) would be due the longer upper deck on the passenger version. Maybe this contributes to extra drag? Maybe not? Your thoughts would be appreciated.

Hardy, feel free to contribute.

Thanks guys.

[Hardy Heinlin]

The freighter's shorter upper deck causes a tiny little pitch-down when above Mach 0.86; but it's too small to be noticeable in the sim, and it's compensated by the freighter's Mach trim * anyway so that you won't notice any difference at all.


|-|ardy


* only up to 0.5° nose-up on the stab trim.

[G-CIVA]

Steve, thanks again for all your efforts.

I'm wondering if you can tell me just in broad strokes what kinds of differences you see between performance in the passenger and freighter versions, when weight, engines, and everything else are kept equal.

Will,

Thanks...the work has been a pleasure for me since I've benefited too!

The FPPM documents purely deal with fuel burn & performance numbers based upon engine type across the entire performance range capability of the airframe. This takes into account the much higher design structural landing weight capability of the Freighter. The only minor differences in the performance tables are the additional columns of weight increase for ERF & ER passenger variations.

Some tables are type specific - such as emergency crew & passenger oxygen capability & within these tables there are even options for additional emergency oxygen bottles. Some operators opted for these to allow them to fly on particular routes.

With regard to the actual performance tables (I have now studiously transposed each one as accurately as possible within the confines of what PFPX allows) there is virtually no difference in fuel burn between a PW 4056/4062 or a GE CF680C2B1F/CF680C2B5F engine.

I am going to have another look at the PW CLB data in the next month just to make sure that everything is correct.

As we speak I am adjusting the FF/DRAG bias calculations for all the PFPX model files. This is based on data I collected using the APMS function of PFPX. The PSX models should be flown with a 0/0 FF/DRAG factor with PFPX calculations offset accordingly. I use the PSX Wind Corridor Function & use the PFPX Flight Plan wind data entered into the PSX wind corridor.

This process will be an ongoing commitment by me.

[Will]

Thanks Steve, that's very helpful.

I'm curious about whether you find the APMS functionality of PFPX to be useful. There is a user over on the PFPX forum who seems to be pretty well-informed about the software (I think he may have even been a beta tester or otherwise somehow close to the developers) and he said that the APMS isn't all that helpful when the performance file is well-written (meaning it matches the manufacturer's specs). Instead, he recommends flying a few routes and then updating fuel and drag biases based on average differences at the end of some flown sectors.

To me this makes sense, as the AFPM seems a bit unwieldy, in that you'd get various drag and bias values for a various weights and altitudes, and then have to decide how to put all of those together in one final pair of numbers. (E.g. just an average? Or a weighted average taking into consideration how much time on a typical sector is spent in the modal flight altitudes? And so on.) Another PFPX user went so far as to make a table that let you interpolate fuel/drag bias as a function of deviation from ISO.

To my knowledge, none of the above individuals were using PSX, for what that's worth.

Anyway thanks again for helping bridge two excellent pieces of software.

[G-CIVA]

Will,

To my knowledge, none of the above individuals were using PSX, for what that's worth.

That might be the crux of the issue...?

The APMS function needs a little bit manipulation to get good numbers .

If you look at the model files that I have uploaded with APMS data included (within your PFPX model file list) you will see that I used an average taken over the total time. The feature takes some manipulation & patience to yield decent figures.

Lots of simmers just don't fly the 744 on sectors on durations sufficient enough to yield decent numbers to play with (no criticism intended).

That's why the FPPMs contain quick reference short range cruise tables & such like.

To obtain good numbers from scratch you need to fly long sectors with accurate weather & wind data inside the PSX environment that matches the PFPX OFPs.

[Will]

Therefore flight planning within PFPX with the PW engine variants using my model files can only be conducted with LRC, M.85 & M.86 cruise options.

Steve, an operational question for you. If I'm going to fly at M.86, and flightplan that accordingly with PFPX, what do I put in the FMC for cost index during the preflight?

I know I can go into SEL SPD on the VNAV page and put in 0.86 for cruise, but before that page is active (e.g. on the ground during preflight), what would I put in the PERF INIT for a cost index? I think you'd want the FMC to give you a fairly accurate prediction of the trip fuel before departure...?

[G-CIVA]

That's part of the problem I encountered with the proprietary FPPM data I have available for the PW 4056/4062 engine. There is no Cost Index data available. I do have access to proprietary FPPM Cost Index data for GE & RR engines.

What to do?

SWAG? (Scientific Wild Arsed Guess)

Or, during FMS pre flight enter xxx/.86 as the ECON CLB SPD on the CLB Page, .86 on the CRZ Page & something sensible like .860/290 on the DES Page.

With your PSX wind corridor loaded & wind data uplinked into the LEGs page you should get a sensible fuel at destination figure on the PROG Page.

Slightly unrealistic...but that's the price you pay to get accurate fuel burn figures. The other option is a native PFPX aircraft file that contains some cost index figures that are wildly inaccurate (in some cases by several thousands of kgs per engine per hour).

Now I have the FPPM data in an aircraft file I will start to accumulate further APMS data to fine tune the bias numbers.

[Will]

As we know, all you need before takeoff are figures that are somewhat predictive and reassuring(*), and your on-the-ground predictions will be overridden by in-flight predictions once you are in the air.

So my SWAG -- please someone correct me if I'm wrong -- is that for preflight, people would pick a CI on the high side, one they think would result in M0.86 at cruise. Maybe 250? Something like that?

But I do like the idea of configuring the VNAV pages for the desired cruise speed ASAP.

*) Maybe the aircraft's pre-departure fuel predictions are not so relevant? I recall talking to a 737 pilot who told me that if the FMC and the OFP disagree on the predicted burn prior to departure, the FMC's predictions are to be disregarded and the OFP is controlling. Once the aircraft hits real weather and has its engines turning, then the on-board FMC predictions take over, unless they disagree too much with the crew's dead reckoning, lol.

[Will]

Also, I'm going to move this most recent question to the main forum, perhaps it will get a bit more visibility there.