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Check_Airman

Possible solution to excessive taxi thrust requirement for 744

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Hi all,Back in the days of 767 PIC, the plane needed too much thrust to taxi (just like the 744). Matthias Neusinger came up with a taxi mod that fixed the problem. His data inserts into the air file via a program called AirEd. I tried the mod last night and it worked! The inflight engine performance seemed to be the same as usual, just that now, we can taxi at idle...Just one problem though- the plane now taxis too fast at idle. She rapidly accelerates to speeds above 25kt over quite short distances when empty. From the readme, the mod only affects characteristics below 30%N1. This way, flight characteristics are preserved. I'm posting this hoping that a developer (or someone who knows about this stuff) can have a look at the data, and see if they can get it to work with the 744.Search avsim for taximod.zip by Matthias NeusingerSearch flightsim.com for AirEd, which modifies the 744 airfileAnyone up for the challenge?Paul

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Guest Knikolaes

I have AirEd.Which value are you changing? Maybe I can have a look . . .

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Guest Knikolaes

K found it. looks like a huge table of . . . numbers. There are no definitions for these numbers at all so there is no way to decipher what does what in this table. This thus goes way beyond my expertise with AirEd.LOL I fear I may not be able to assist here as I have no idea which values we are experimenting with here. Anyone else?

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The readme from the taximod file has the info, I've pasted it below:Taxi thrust modification for 767 PICThis modification will allow you taxiing at idle thrust with 767PIC while it should not have an effect on performance in flight (although I cannot say for sure, so please try it and tell me via the 767PIC forum if you find any side effects)Only use this modification with 767 Pilot in Command and FS2002! (It wasn

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Gents-Yes- you ARE changing performance parameters that will effect the airplane. In this instance you are adjusting friction coefficients that define the relationship between the airplane's tyres and the surface upon which the airplane is rolling- including lateral and longitudinal friction (Which effects skidding and nose gear steering adhesion.)One easy example: Shut down engines 2-4 and leave #1 idling... The airplane will rotate around in a circle at a speed that is dependant upon your weight and the surface you are sitting on.There are other side effects as well...If it were as "simple" as changing a single number someplace- I assure you it would have been done LONG before the product went into general release. (I recognize that this runs contrary to the generally accepted presumption that commercial developers don't know what they are doing- but the truth is we generally know quite a bit about what we are doing and design decisions are made with cause/effect in mind.)So please note carefully that your license agreement (to which you agreed!) prohibits hacking/modification of the files that come with your PMDG product- so please do not go modding unless you are comfortable with the potential results- and do not under any circumstance contact us for help if you mod yourself into a hole... ;-)(We have to draw some limits someplace....ahahahahahha)


Robert S. Randazzo coolcap.gif

PLEASE NOTE THAT PMDG HAS DEPARTED AVSIM

You can find us at:  http://forum.pmdg.com

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Robert,I wasn't trying to suggest that u guys don't know what you are doing. It's obvious fom the quality of the product that you know quite a bit! I was just hoping it was something you may have overlooked accidentally.Also, I realize that I can't edit the files and then expect support for my newly customized product.Paul

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Actually, the guys here are modifying the idle thrust that the engine produces below Mach 0.04 (which will only be achieved on the ground). I've heard it rumored that a certain 767 uses the same technique (with an additional hack in the fuel flow gauge to make the idle fuel flow look normal again).Search the support forums of a certain Super 80 for "fuel flow 767" for more information (it's on the protected side of the forum).Another popular fix for the taxi thrust problem modifies the fricion coefficients in sim1.dll (which is probably what you were thinking of). This has the disadvantage of affecting all aircraft, though, along with the changes in handling characteristics that you mention.Martin

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Yeah we're aware of these things, but I know Vangelis had his reasons for not using them when designing the 747's FDE. The dll friction hack is against the Microsoft EULA in a similar manner to the no-cd crack and we can't condone the use of that either...


Ryan Maziarz
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For fastest support, please submit a ticket at http://support.precisionmanuals.com

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There is another 'legal' way to modify the FS weird friction coefficient, without touching any PMDG files. I've read somewhere that editing the SIM1.dll in the FS General Module folder helped some folks.Dont ask me how, just search here in the avsim forums.I agree I am for one annoyed by the fact I burn twice the fuel I'd need in reality to taxi the plane to the runway, but I leave with it.I dont pay for the fuel anyway :( EDIT: oops, sorry, I missed Martin's post about the SIM1.dll


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Guest Knikolaes

Well, hey -- while we're on the subject, anyone know if FS X will have better ground handling for such speeds? I have the demo, but been having sound issues and I hate not having my mouse panning in the VC so i haven't played with it much - especialy since i have no aircraft in the demo that i am familiar with power settings or breakaway/taxi speeds.

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Guest Peter Bowcut

The .air file thrust modification described in this thread, while producing good taxi characteristics at low power settings, had some serious drawbacks in my tests. Firstly, taxiing at speeds greater than 7-10 knots is difficult, even impossible. Not sure why this is true. Also I've discovered that this .air file mod produces weird (insufficient) climb rates in flight. In my experience this mod affects too many other characterisitics and isn't too good a thing for the PMDG 747 sim.Conversely, I read up on the 'recipe' as how to mod the sim1.dll file with a hex editor in order to reduce taxi friction. I dropped my modded .dll file into FS2004 and gave the PMDG 747 a whirl. I will have to admit I'm very pleasantly surprised at how dramatically more easy and precise taxiing is for me now. I really can't see any drawbacks in normal flying, although the takeoff run distance is going to obviously be a little shorter (not much!), and braking distance increases somewhat. However, it's 100 times easier to taxi with realistic procedure. I know Robert Randazzo is not too thrilled with these 'back alley' techniques, so I'm certainly not going to push it here. For me personally though, the sim1.dll mod overcomes the only non-realistic thing about the PMDG sim (having the feeling of taxiing in wet cement as someone once describe it), and I love it. It's a huge shame Microsoft hasn't been able to overcome the ground friction limitation in either FS9 or the new FSX. Maybe Pete Dowson's arm can be twisted to do some of his magic with FSUPIC down the road. :) At any rate, I love being able to have a totally realistic overall experience with the PMDG sim, including movement on ground now. It's awesome.

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> For me personally though, the sim1.dll mod overcomes the only>non-realistic thing about the PMDG sim (having the feeling of>taxiing in wet cement as someone once describe it), and I love>it. Me too!. And btw, I love that if 'fixes' things for **ALL** aircraft - as it should ;)Also, I compare the dll 'hack' to someone replacing the ground textures or cloud textures - an endless activity in FS series. If they can do this why can't I change friction numbers?. It simply makes no sense - so I am not losing sleep over this 'crime' :-lolMichael J.


Michael J.

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Guest airx3000

The sim1.dll solution is definitly the good one at least for airliners ( i heard it mess things up for helicopters )With the 744 i am able to taxi with only 30 - 33 % N1 depending of the weight (should be idle most of the time in real life )The turns are now smooth as silk.With the 737 you can taxi at idle trust as in the reel bird.I din't notice any side effects execpt the small ones already described.

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Guest Knikolaes

May i ask if anyone can rovide feedback as to the effects on GA Aircraft? If the only neg effects are on helicopers, then by all means I don't care about that -- I am fixed wing only and would d anything to make my simming experience more realistic so that i may practice -- since I use the sim to go over real life lessons from my flight school (working on my coordination with stalls now - that's my only weak spot).Chris

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