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Guest Catandra

Spool up time in Turbine aircraft

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Hello allI was wondering if anyone knew of the way you can alter the cfg file to reduce the spool up time (lag time) for a turbine powered aircraft. I fly these for a living and its my humble opinion that the sim exaggerates the effect. That is to say, there is far too much delay between the application of power and the resulting thrust.I made this change a couple years ago but now I've forgotten what it was.I would appreciate any help.Thanksadmiraltysignaturepic.jpg

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For jet (and probably turboprop) engines, fuel_flow_gain in the aircraft.cfg is the way to change the spool up times (higher values -> faster spool up).

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This goes out to the both of you, for asking the question and for the answer.Thank you so much!This was a question I also have intended to ask for several weeks now.Monty

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For FS and the limitations it has, it is going to be hard to simulate becasue the spool up time is not linear. It all depends on what N1 you are currently at when you initially apply power. I flew the conquest 1 and it idled at about 52%. If you jammed the throttle up quickly there was a huge lag for it to react. The King Air 100 idled at 60% bu the lag was minimal when compared to the conquest. Same goes with the 737. When at idle the is quite a lag to 40% but after 40% to take off thrust the lag drops off quite a bit.

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Alex-Is that the same as Fuel_Flow_Scalar?Also, does anyone know if you can add parameters to the cfg file if they are missing? For instance, the Aeroworx King Air is missing the entire flight tuning portion of the cfg file. I'm wondering what would happen if you added all or part of one.Thanksadmiraltysignaturepic.jpg

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>>Alex->>Is that the same as Fuel_Flow_Scalar?>>Also, does anyone know if you can add parameters to the cfg>file if they are missing? For instance, the Aeroworx King Air>is missing the entire flight tuning portion of the cfg file.>I'm wondering what would happen if you added all or part of>one.>>Thanks>Interesting question. I suggest you also ask in aeroworx forum. You should get an answer there.

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This is the one thing that's been bothering me about the DA Cheyenne: spool time. I just changed the fuel_flow_gain from .03 to .06 and what a difference! There's still a lag but now it seems much more controllable; especially when taxiing. Flight is much more controallable now also. What a great tip! :-jumpy Mike

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>Is that the same as Fuel_Flow_Scalar?No.>Also, does anyone know if you can add parameters to the cfg>file if they are missing? For instance, the Aeroworx King Air>is missing the entire flight tuning portion of the cfg file.>I'm wondering what would happen if you added all or part of>one.Yes...flight tuning params are optional...if they're in there they override the defaults. You can add all, some, or none.RegardsBob ScottATP IMEL Gulfstream II-III-IV-VSantiago de Chile

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Great. Thanks Bob. Just to clarify...do I understand that a new flight parameter will supercede that aspect of the plane rather than just adding to the value?What I mean by that, is that in the B200, there is no flight tuning section. But obviously, its written into the flight model. So if I add something like Fuel_Flow_Scalar (or whatever), will it replace the existing parameter or add to it?Thanks for your helpadmiraltysignaturepic.jpg

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A better way to edit this would be to go into the air file and edit the 1505 table. I have had high success changing the curves in there to give me a realistic engine stabilization time, and a low spool up on the bottom end and a high spool-up rate at the high end.Here's what my table 1505 looks like for one of my projects. The pilots who've tested it (real type rated pilots) say the engine response time is excellent:1505.jpgThe X value is a time constant and the y value is the engine turbine speed (N2, HP stages). As you can see, the engine spools very slowly once the fuel is introduced, and stabilizes around 65% N1. Now, from around 65 to 85% N2, the spool rate is increasing gradually. By the high end of the N2 spectrum the engine response time is increasing exponentially. Once you get all those heavy turbines and that big fan at the front moving it's easier to get them moving even faster.

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>>Alex->>Is that the same as Fuel_Flow_Scalar?>>Also, does anyone know if you can add parameters to the cfg>file if they are missing? For instance, the Aeroworx King Air>is missing the entire flight tuning portion of the cfg file.>I'm wondering what would happen if you added all or part of>one.>>ThanksMight want to try a re-download of your Aeroworx Super King Air B200. I've got all the flight tuning perimeters in my cfg copy. Plenty of tiny tweaks have been used and/or suggested along the way as well, most having to do with tuning the cfg perimeters. There is also a v2.1 and now a v2.2 update release as well.Thought you may want to know.

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If you're tweaking on the .cfg then you're not doing it correctly. All these small tweaks and changes to the flight dynamics should be done in the .air file. Unless you're adjusting the load and balance or contact points.. very basic aircraft geometries, this all should be done in the .air file.

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hmmm... well, since most of the data in the airfile is written to the aircraft.cfg, then the average joe would be better off doing a few known tweaks in the cfg since it (the aircraft.cfg) overwrites/amends, so to speak, the .air file where data is included in both. Otherwise, a successful tweak to the airfile would mean the user would have to eliminate the corresponding section in the cfg so a new cfg section could be written to the cfg and thus not override the airfile.Sometimes an airfile adjustment is absolutely necessary to get the correct dynamics; after that, most adjustments can be done satisfactorily via the aircraft.cfg.This may help clear up a bit of this long discussed discrepency:http://forums.avsim.net/dcboard.php?az=sho...ing_type=search

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