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Guest JeanLuc_

Gear Drag in FSX air file???

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Hi there,I recently imported a version of the superb Meljet 777-300er into FSX .Now we all know that this model was originally created for FS2002(In fact i migrated straight from FS2002 to FSX, skipping FS2004)Ive managed to sort out the odd, cruise pitch issue etc etc & the aircraft is behaving quite nicely now.However i've noticed that when the Gear is extended, there seems to no longer be any drag component ...In the past, editing the values of the 'Drag' coefficient under part 1101 in the .air file did the trick...The flaps create drag, the spoilers create drag.. but not the gear!Can anyone shed some light please on what param needs to be changed & by what ammount for a heavy like the 777 so that lowering the gear adds drag!Many thanksHyper 'Al'

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This is unusual indeed since gear drag coef (for full extension) has not changed (1101:22h) in FSX as compared to previous versions of the sim and there is no additional aircraft.cfg parameter. Are you sure the gear was really extended in your tests since there is an inhibition speed limitation defined in the contact points section of the aircraft.cfg file (see SDK)? Typically max gear drag for such heavy aircrafts will range from 100 to 150 (0.05-0.075).Herv

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Hi there,Many thanks for getting back to me.The gear is definately down... inside - 3 greens, Outside - The gear is there, out & locked.My test that always in the past has worked is simple.... Use the autopilot to maintain a constant airspeed. Introduce something that creates drag.... flaps, spoiler etc, & you see the engines spool up more to compensate, in order to keep the same airspeed.If i do this with the gear on the 777-300, nothing happens... the airspeed stays the same, & the engines remain at exactly the same levels.This experiment DOES work with other FSX aircraft though...Perhaps i need to change the 'airframe' type number to an FSX one??? - I have a list of airframe numbers, but it only goes up to FS2004, Do the new FSX aircraft have (including the heavies)different airframe numbers, compared to their equivalents in older sims?CheersAl

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>Do the new FSX aircraft have (including the>heavies)different airframe numbers, compared to their>equivalents in older sims?I don't know but I don't think it will have any effect on gear drag.Also check for a 1540 record in your airfile. The Cdg value at 1540#10 (it's a double), if any, will override the 1101 value. No more idea ;-)Herv

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This is getting stranger..MAybe someone else can doubel check this...Contrary to what i mentioned earlier, I tried a similar test on the stock default 747 that comes with the sim....Using the autopilot to maintain 4000ft, & auto throttole to hold 220kias, (appropriate flaps for nose level), I noticed that Lowering & raising the Gear, had NO effect on Engine RPM etc.... Therefore NO drag componant when extended...Can someone else please try this & report their findings, as if true... it seems a significant bug/ oversight by Microsoft?CheersHyper

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>>>>Can someone else please try this & report their findings, as if true... it seems a significant bug/ oversight by Microsoft?<<<

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In my personal opinion, you cannot achieve what you try to, because the knowledge you are using for flight models is FS6 or FS7 based (namely, the decoded sections of the .air file).FS9 and FSX have new non FSX SDK documented sections that might achieve what you are looking for.I'd like to help more if I could.

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>FS9 and FSX have new non FSX SDK documented sections that>might achieve what you are looking for.This is interesting Jean Luc. Which ones?Herv

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Hi there,Many thanks for replying Everybody...This is intruiging, as you're basically implying that the .air file itself is increasing having bugger all to do with how the plane operates? - Therefore if a characteristic of how the plane flies in NOT found in the .config file, or the .air file either (as used to be the case), Where & whatthe heck is FSX doing to control how a plane behaves?If there is some generic 'central' config file now ... won't this affect ALL aircraft?Very much interested to learn more..Cheers

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>>>>In my personal opinion, you cannot achieve what you try to, because the knowledge you are using for flight models is FS6 or FS7 based (namely, the decoded sections of the .air file).<<<

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I'd be interrested too! what I did is simply look at fsx .air files with an hex editor, and see there are new sections no one knows about/has documented (me included).So to me the conclusion is easy: what we use to tweak airfiles is outdated and only relies on back compat code, not new fs9/fsx flight model engine...Which lead me to think the key to what you are looking for is not accessible since out of reach of both the tools, and the knowledge.

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