Corrections for PMDG FDE in FS2004

[Bob Scott 7,714]

Here's what I have done to preserve the FS2002 PMDG flight dynamics in FS2004. It involves some modification to the B737-700.air and aircraft.cfg files...these are for the -700.FS2004 ignores the wing incidence and twist parameters, resulting in about 0.5 deg more nose-up attitide for a given AoA in FS2004, and there is a significant increase in induced drag resulting from this and other changes in the way FS2004 does flight dynamics. After the mods, I have pitch, trim, and cruise fuel flows consistent between FS2002 and FS2004.RegardsBob ScottATP IMEL Gulfstream II-III-IV-V L-300Washington, D.C.========================================MODIFICATIONS:In B737-700.air:Table 1101 Cmo = 0.10 (was -.00488)Table 1205 HStab Incidence = -1.0 (was -.5, may not have effect in FS2004)Table 404:X Y-3.141600 -0.240000-2.748900 0.359900-2.346423 0.500000-1.953723 0.359900-1.561023 -0.070000-0.164723 -0.078000-0.094943 -0.040000-0.042583 0.067000-0.025123 0.1290000.009777 0.2461500.027227 0.3432100.201757 1.2658200.210487 1.3028800.220957 1.3350000.232306 1.3500000.245396 1.3600000.257614 1.3450000.267213 1.3200000.283794 1.2200000.341390 0.7600000.372805 0.5600000.393749 0.4650000.428656 0.3500000.463563 0.2740000.550829 0.2040001.580577 -0.0285002.356200 -0.3600003.141601 -0.240000In aircraft.cfg file:-airplane_geometry-wing_incidence = 0.00 (was 1.0)wing_twist = 0.0 (was -2.75)htail_incidence = -1.0000 (was -0.5000)-flight_tuning-induced_drag_scalar = 0.71

[bobbyjoh 11]

Hi Bob,Took a look at your work and did made the changes to the aircraft.cfg. However the same files in my FS9 version airfile don't contain 1104 or the 404 tables with reference to Cmo or the complete 404 inputs.Where and how did you find the tables.ThanksBob Johnson

[Bob Scott 7,714]

Bob; Cmo is in table 1101 (Primary Aerodynamics). Table 404 (Aoa vs CL) is certainly there...it's required for any model. I dumped the airfile using the AirUpdate program (available at www.mudpond.us), modified the table 404 figures there, and reinserted the changes back. You can also manually edit the points in AirEd or AirfileManager...only the X coords changed (shifted right by .008 radians). The Cmo value is about halfway down table 1101, and you'll see it with either AirfileManager or AirEd with Herve' Sor's updated AirEd.ini file.CheersBob ScottATP IMEL Gulfstream II-III-IV-V L-300Washington, D.C.

[Bob Scott 7,714]

One more noteIn AirEd, Cmo is labeled Pitch moment coefficient at AoA=0 (CoG offset)The value shown in AirEd is 2048*Cmo...so you need to enter 205, not 0.1If using airfilemanager, you enter 0.1 directly...it does the factoring for you.CheersBob

[bobbyjoh 11]

Thanks Bob,I will now go back and make some changes to the airfile since it was changed with the update.BobKDEN

[bobbyjoh 11]

Hi Bob,I downloaded the airupdate program, thanks and made the changes in the 404 tables, plus all the other changes in the air file and aircraft.cfgHowever using AirEd, the line you gave me: The value shown in AirEd is 2048*Cmo...so you need to enter 205, not 0.1does not quite read what you said, there is no 2048*Cmo, but the current value is 0.1. I am going to change that value to 205. I hope that is correct. Please let me knowThanks for everything BobCheersBob Johnson

[bobbyjoh 11]

Bob, right after I sent the previous post, I tried to make the change from 10 to 205, but AirEd, won't let me make that change. Is that OK?CheersBob

[Bob Scott 7,714]

Bob; Don't know what's happening to you with AirEd there...the original value (using AirEd 1.52 here) is -10...I changed it to +204 without a problem. I expand table 1101 by left-clicking on it, then select Cmo by clicking on the value (pitch moment at AoA=0 (CoG Offset)) and enter 204 in the text box that openes up and press . If that doesn't succeed, I'd suggest you go find airfilemanager...it's point-and-click. If you use it, the default value is something like -0.00488 and the corrected new value (it does the conversions for you) is +0.10RegardsBob ScottATP IMEL Gulfstream II-III-IV-V L-300Washington, D.C.

[kerosene31 349]

Would someone from PMDG allow you to post these changes so we could download them? Or are they working on this problem themselves?

[crvm 0]

This is one man's opinion, not to belittle anyone's efforts but messing with air files should never be done by people who do not have a complete knowledge of all aspects of the air file. There was a "Taxi Mod" for PIC that was claimed did not effect anything but the thrust for taxi, well I pointed out that this was not true and got flamed for doing so, but in the end anyone using PIC could tell that it did effect much more than taxi thrust. So be carefull, I would encourage you not to mess with it... [h4]Best Wishes,Randy J. Smithhttp://img.villagephotos.com/p/2003-8/196432/winglets_lg.jpg [h3] AMD XP 2200 |MUNCHKIN 512 DDR RAM |ECS[/b ][i] K7S5A MB[/i] |GF2 MX 32 MEG and still runs GOOD!|WIN XP PRO |MITSUBISHI DIAMOND PLUS 91 19"[/h3]

[Guest ilh]

The question for PMDG is have they investigated FDE differences due to FS8 vs. FS9? Apparently Bob Scott found some differences, and it would be nice to hear from PMDG if they have or plan to investigate his findings.Lee Hetherington (KBED)

[vscimone 16]

As for uploading an updated airfile... we can not permit that.As for investigating any findings... I'll leave that up Vangelis to reply.VinPMDGwww.precisionmanuals.comhttp://www.vinscimone.com/dancnkid.gif

[Guest mmcevilley]

>This is one man's opinion, not to belittle anyone's efforts>but messing with air files should never be done by people who>do not have a complete knowledge of all aspects of the air>file. No - it is much bigger than just one man's opinion. This issue is well documented in the MSFS forum. A proposal of required corrections has also been well documented in the MSFS forum.Note that the very first statement made in regards to the change was "... this is what was done to preserve the flight model ...". That statement alone indicates that some degree of behavioral difference has been noticed.The only way to validate such claims is to do the research, make changes, run the tests, document the findings, conduct the analysis - and do it again, and again, and again ... until you either achieve the desired results, settle for an acceptable compromise, or, through these efforts refute the original claims and move on to the next problem. The process is long, meticulous, oftentimes extremely frustrating, but it is the only way that issues with this degree of complexity can be resolved.In the interest of furthering the fidelity and accuracy of the flight model - experimentation is required. We should be commending those that have the interest, motivation and capability to do so. We should not be rejecting their efforts or discrediting them through insinuation. Progress does not come from remaining idle and accepting less than perfection. The art of engineering is to achieve that "perfect balance" between the optimal goals and what is practically achieveable given the constraints of the environment.Besides, Mr. Scott knows his stuff. I for one commend him on what he has brought to light!-michael

[crvm 0]

That all sounds good except for one important factor, he does not know this aircraft like the developers. He does not have a clear kowledge of what effects what in this file, and,why or how. Plus who says PMDG are not looking into this or have been?? [h4]Best Wishes,Randy J. Smithhttp://img.villagephotos.com/p/2003-8/196432/winglets_lg.jpg [h3] AMD XP 2200 |MUNCHKIN 512 DDR RAM |ECS[/b ][i] K7S5A MB[/i] |GF2 MX 32 MEG and still runs GOOD!|WIN XP PRO |MITSUBISHI DIAMOND PLUS 91 19"[/h3]

[Bob Scott 7,714]

OK folks; I had to stop writing and delete the first draft of my answer to Randy Smith's post. Here's take 2. Randy, take a look through the MSFS Aircraft and Panel Design Forum. Please let me know if my work there leads you further to believe I don't have a "complete knowledge of all aspects of the air file." Fact is, I've been hip-deep in exploring the inner workings of the FS9 FDE since it was released. The lessons I've learned in that effort are what I put to work in writing a number of FD modifications for airfiles in FS2004. Give me some specific shortcomings that result from my suggested mods, not unfair parallels to a foodfight you once fought over some other guy's mod to some other airfile some time in the past. The changes to FS2004's FDE affected PMDG's careful work on the FS2002 737-700 FDs. I applied the knowledge I have gained on the differences in new FS2004 FDE to correct performance back to what PMDG coded into its FS2002 FD. Where, I ask, is there a better solution to be had? Let me know...I want it, too. In the meantime, I offered it up as free advice to my friends here. For the record, I have over 30 years of real-world experience in everything from sailplanes to supersonic jets to heavy 4-engine jet transports, including over a thousand hours of jet instructor time. I also earned a four-year college degree in computer science and worked my way through college as an application programmer. I feel quite comfortable in my qualifications to translate the differences between a computer simulation and the real thing. It causes me some pain to have my work publicly criticized by a guy that: a) hasn't even tried it out yet and has nothing concrete to offer in critique, and :( probably has more posts in this forum than actual flying hours in his logbook. The choice is yours: try the mod or stick with the status quo...machts nichts bei Mir.RegardsBob_____________________________R. J. Scott, BS, MS, MSS, MBAAirline Transport PilotInstrument Airplane Multi-Engine LandG-1159 G-IV G-V L-300Commercial Priveleges Single Engine Land