Which is the right step climb?

[GodAtum]

What Simbrief says or what the FMC says, as I find they are often different?

[Jeroen Hoppenbrouwers]

The FMC knows what it can do right now. Anything else was crystal ball.

Hoppie

[simonijs]

Dag Jeroen,

I think information from the FMC should - to a high degree - be in accordance with what is presented to the crew through manuals. I have looked into this (OPT/MAX ALT) as well, using AOM and/or FCOM. For instance, this table from KLM's AOM Volume III (hopefully I won't be sued for this):

http://www.hoppie.nl/forum/var/AOM_B744_LRC_table_(1).jpg[/img]]

As you can see, at higher weights you would have to loose 20 tons before moving to the next shaded optimum Flight level. At lower weights (± 250 tons), this subsequently happens after 10 tons of fuel burn. In PSX, this "knee" occurs at higher weights (from ± 285 tons). Indications of OPT ALT then start to deviate seriously from this graph (and from step climb predictions in SimBrief).

MAX ALT figures are limited by Buffet Limit (1,3g bank maneuver capability), and by Maximum Climb Thrust. Given altitudes for Max Climb Thrust are always (slightly) higher than values for 1,3g. FCOM I states at some point that - at OPT ALT - there always is at least 1,5g maneuver capability. For some time now, I am trying to find a decent equation that is able to calculate these 1,3 and 1,5g altitudes for all 747's. KLM's freighter has a MTOW of 412,7 tons, the PAX/Combi versions 390,1/396,9 tons, so I guess for each and every aircraft such tables would exist.
Exact OPT ALT figures are given in the Performance Dispatch section of the FCOM for both the Freighter and the PAX/Combi aircraft (LRC however), but they are not the same for same weights. 340T for the Freighter: OPT ALT = 33100 ft; 340T for the PAX/Combi = 32100 ft. So hence: a decent equation is required and Boeing has it.

GodAtum: FMC OPT ALT figures are given for "No Wind". I am not sure whether or not SimBrief is calculating step climbs, dealing with forecasted upper winds. Because that would produce some difference as well.

In November 2017, Hardy wrote:

As I wrote further above, a more precise solution would be this: On an altitude graph calculate a Mach and grossweight progress curve for a given cost index, or a given LRC or SEL, E/O, MCP SPD. And then search for the crossing point of that curve and the database MAX ALT curve.
« Last edit: Wed, 22 Nov 2017 18:14 by Hardy Heinlin »

Well, maybe I can be of help here... (by e-mail)

Regards,
Simon

[Hardy Heinlin]

What I suggested in that quote last year has been implemented this year and it works, I think. This is not related to the OPT ALT curve per se for which PSX uses Lufthansa data. Nuances may be airline specific. I can't make everyone equally happy in this case. Just set your airline's suggested step climb points in the FMC LEGS pages. The FMC calculations will use them instead of its own points.


|-|ardy

[G-CIVA]

In a blatant plug here for an excellent piece of planning software why not get hold of PFPX:

http://www.flightsimsoft.com/pricing/

You have already spent a considerable amount on the finest simulation product of a widebody commercial airliner, why no spend a little more & your flight planning woes will be over since I can hopefully help unlock the mystery of flight planning this behemoth for you?  The data you have just seen on this forum post regarding cruise performance for this engine type is already available for the GE engine series of B744 & B744 ER airframes within PFPX, as are all of the RR variants.  I am currently working on the PW series of airframes.

http://aerowinx.com/board/index.php?topic=4820.0

As a Beta Tester I can reveal that after a very long period of hiatus we are now on to v2.0, I expect a public release in the not to distant future with many improvements.

Just my 2 cents for you ...

[simonijs]

Hi Steve,

I would be very happy to buy PFPX, but there are a lot of MAC's at home...

Regards,
Simon

[cavaricooper]

Simon-

Steve's work, together with PFPX are a BRILLIANT combination.  I would strongly urge considering Bootcamp or just a cheap Windows laptop for this purpose.  I work on Macs all day long, however, I still maintain my networked PCs- ONLY for flight simulation.

Version 2 now includes Terrain Depiction and is superb for escape route planning, approach and departure considerations, etc. Coupled with our man Bell's files it is everything you want and need for despatching a 744 worldwide (I'd hazard that the real aeroplane would arrive safely also). It should be available in the very near future.

FWIW

C

[DougSnow]

Hi Steve,

I would be very happy to buy PFPX, but there are a lot of MAC's at home...

Regards,
Simon

I have a mac here too.  I work with a professional version of PFPX, and a bunch of Boeing and Airbus performance software, the entire MS Office Suite, MS Access, MS Project, etc., all thru Parallels Desktop on my mac.

All programs work just fine, the install was quick and painless. My mac monitor is iOS and my external monitor (when I am home) is Windows 7 all on one desktop. Even when I am out I can run IOS/Windows just fine and just slide my hand across my trackpad and slide between IOS/Windows. Under the tree is my new MacBookAir (8G/256G); cant wait. The entire virtual machine file that contains all the Windows 7 files and your programs is about 70GB (at least mine is) so you'll need some flash drive space.

My wife has a bookkeeping business on her Win10 Laptop and 10 drives her crazy, Win7 on Parallels just works.

I'll never purchase another PC anything again...

[Pierre Theillere]

Hi all!

I'm also a Mac guy... I used to use Parallels (on an old MacMini that died), but some time ago I tried "Crossover" (it's the "more polished" and commercial version of "Wine") and TOPCAT was running straightforwardly.
And, yesterday, I managed to run PFPX v2.00 (currently in testing) under latest Crossover, on MacOS 10.14.2.. The trick was "simply" to first create a new virtual machine (they call it a "bottle") on Windows 10 64-bit and install VisualC++ 64-bit version 14, and only then install PFPX v2.00 in that same "bottle".
For now, the only odd things that I noticed is the icons on top of the map aren't dispayed, but they were "active" with the tooltips to guess them.
So... to all Mac users: that may save you some computers and money, and simplify the day when PSx can use flightplan's upper altitude enroute winds!

[GodAtum]

In a blatant plug here for an excellent piece of planning software why not get hold of PFPX:

http://www.flightsimsoft.com/pricing/

You have already spent a considerable amount on the finest simulation product of a widebody commercial airliner, why no spend a little more & your flight planning woes will be over since I can hopefully help unlock the mystery of flight planning this behemoth for you?  The data you have just seen on this forum post regarding cruise performance for this engine type is already available for the GE engine series of B744 & B744 ER airframes within PFPX, as are all of the RR variants.  I am currently working on the PW series of airframes.

http://aerowinx.com/board/index.php?topic=4820.0

As a Beta Tester I can reveal that after a very long period of hiatus we are now on to v2.0, I expect a public release in the not to distant future with many improvements.

Just my 2 cents for you ...

I'll have to plug Gary's Dispatch Suite which integrates into PSX and Simbrief

[Pierre Theillere]

Hi All,

Just "reviving" that old topic, mainly due to the release of the NG FMC... and its built-in improved enroute wind modelling! So PFPX is becoming really useful for precise flightplanning and fuel planning, when using PSx standalone, without any visuals generator and associated weather tools.
The sad news: on the Mac, both PFPX and TOPCAT no longer work with the latest CrossOver 19.0 (same with 19.0.1)... But the good news are: reverting to CrossOver 18.5 solves all issues. (and on CodeWeavers website, you can download previous versions, after logging into your account: amazing!)
Note that if you switched of MacOS 10.15 "Catalina" you need to update to CrossOver 19.0... so staying on MacOS 10.14 avoids a lot of problems for now!

[Will]

I had been using PSX on an iMac from 2010, which finally got too slow to use and was not worth repairing. (I had long since updated my home productivity and other non-work computing to a MacBook Pro, but I kept PSX on the desktop Mac because of the large screen.)

Well, since that machine was from 2010, it was really time for a replacement. So last month I bought a cheap Windows computer and a cheap (but good) 32" monitor, and it's a great setup. Now I can run PSX, PFPX, and TOPCAT all on the same device. The cheapest Windows machines on the market have more than enough power to run PSX really well.