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Guest sfflyer

How Accurate is the PMDG NG FMC and Flight Model?

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Guest sfflyer

I'm using the 737NG in a lab setting to look at low cost commercial-off-the-shelf simulation tools for applications like time-dependent trajectories. One of the issues that comes up pretty often is the fidelity of the simulation to the real aircraft. While most of the FMC functions appear to be accurately modeled (but having RTA would have been nice), I'm interested in how close the FMC generated numbers are to the actual Smiths U10.4 logic, and whether the general performance on climb, cruise, and descent are close to book numbers.Thanks!

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>I'm using the 737NG in a lab setting to look at low cost>commercial-off-the-shelf simulation tools for applications>like time-dependent trajectories. One of the issues that>comes up pretty often is the fidelity of the simulation to the>real aircraft. >>While most of the FMC functions appear to be accurately>modeled (but having RTA would have been nice), I'm interested>in how close the FMC generated numbers are to the actual>Smiths U10.4 logic, and whether the general performance on>climb, cruise, and descent are close to book numbers.>>Thanks! This AFDS is the most advanced ever created for the 737 NG on a desktop computer. The FMS is based strictly on FPPMs from Boeing and can be flown "by the numbers". While not every single FMC item is modelled it certainly is not lacking anything major in regards to U10.4. (This is in regards to the 800-900 package) From VNAV-LNAV-LVL CH-V/S and even CWS is fully modelled to real world standards. Not bad when one considers a FMS trainer costs well over 1000.00 US. For complexity pay close attention to the APP MODE and the PFD in final. You will have the ILS confidence check passing 1500 RA when the AFDS couples the second A/P (If second A/P is ARMED)! Bias trim at 400 RA. No other 737 has come close to these types of things. VNAV is fully modelled so you will have PATH and SPD VNAV modes. You will get reversion to LVL CH when you reach MMO/VMO (if you let speed bleed that far). You have correct PFD spd bugs for both types of panel (EFIS/MAP PFD/ND) you also have airline specific options like HDG SEL or WINGS LEVEL and RA displays. You can expect correct modes and the proper times like selection of a CMD in TOGA will engage LVL CH as the default pitchmode. You have CRZ CLIMB, so detailed that when you have the CRZ page displayed on the FMC and dial the MCP to another altitude it will dynamicallu appear in the CDU's scratchpad. Set it back to the CRZ altitude and it will blank! So many "little" items and is why those who really know the 737 NG and it's systems are greatly impressed for a 39.95 toy. Mr. Brad Marsh who flys for Pacific Blue has stated some interesting things in regards to this sim. You can visit his page here http://homepage.powerup.com.au/~speedy/QUOTE' "the PMDG 737NG addon for MSFS9 is an amazing piece of work. It is so good we can use it to train for real world operations. In terms of an positive endorsement I don't think you can say much more than that about any sim.", [h4]Randy J. Smith[/h4]

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Depending on what you are using it for, I would be very careful in using the 737NG for trajectory modeling. The FMC, as Randy points out, is very well modeled in terms of functionality, but the trajectory modeling you appear to be interested in is very dependent on the fidelity of the flight model. If you are attempting to extrapolate to real world performance and use this in any official research that may affect airspace use, I suggest contacting PMDG directly and asking questions like what type of structured flight model validation may or may not have been done, rather than asking your question in this forum. This forum is mainly for the user community; the developers don't post very often.If your efforts are not connected with the current work going on in developing future airspace improvements, well never mind!!Don S.

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Guest frazer

I can only refer to the FFS of the B737NG, but I can say that (like veryone else) the FMC is quite accurate. If you can program the basics in the PMDG you also can in the real aircraft.The flight-model isn't as good as the FMC. I can't say if it's the restrictions of Microsofts "aerodynamics"-engine or the programming of the air-file, but I dont feel the "heavyness" of the aircraft in low speeds like takeoff and landing compared to the real thing. (and yes, I'm comparing at the same speeds and weights).

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Guest sfflyer

I'll talk to PMDG. The purpose of the research is to look at using lower cost tools to validate stubby pencil calcs on timed waypoint arrivals. As far as flight model is concerned, handling is secondary if the performance numbers (ROC vs, power settings, GW, temp, etc.) are on. I'm gathering info to see just how close the PMDG stuff might be, and assess what sort of errors are generated in FS9 versus within the NG package.

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The PMDG is my favority FSim jet airliner, an amazing aircraft!Last month, a first officer friend of mine who flies the 738NG for American tried my PMDG AA 738NG and was amazed at the similarities.He only found a couple of basic differences: In comparing it with the real bird, he told me that the PMDG 738NG taxies like a Cessna 172, whereas the real bird feels much heavier when taxing and it is easier to keep on the taxiway center line.The only other observation he made was that, on approach, the PMDG 738NG flew with its nose up. With similar PAX, weight and fuel left, the real bird does not have that nose-up attitude. He applied extra flaps at 180 knots and the PMDG still flew with the nose up, and he is sure (as he flies it every day) that the real bird is not like that.This hobby is so advanced and amazing that we are now comparing $60 addon aircraft with multi-million dollar airplanes, and we can only find a few differences.Best regards from KMIA,Kerke

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Guest gremel

Kerke,Amazing info. Did he observe this nose-high landing configuration from the 'outside observer view' setting, or was he in the 'L' Landing view setting. If he was in 2D mode, he could have adjusted his seat position by 'Shift-Enter' or is it 'Shift-Backspace' a few times to get the downward looking view that he may be accustomed to looking at on the approach/landing phase. Anyways, it is still very interesting that he was so amazed by it as I am also.Regards,jack

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