I am trying to correctly model the GE CF6-80C2D1F engine. Here is what the engine sections looks like in the aircraft.cfg[GeneralEngineData]engine_type=1 Engine.0=10.666667,-26.833333,-5.500000 Engine.1=-69.500000,0.000000,17.333333 Engine.2=10.666667,26.833333,-5.500000 fuel_flow_scalar=.82 [TurbineEngineData]fuel_flow_gain=0.002000inlet_area=61.000000rated_N2_rpm=32360.000000static_thrust=54700.000000afterburner_available=0reverser_available=1Concerning the rated N2 rpm, here it is set to 32360, but the actual maximum N2 rating on the CF6-80C2 series is 11,055 RPM. Does this need to be changed then?I have the inlet area at 61 sq ft, the actual value for the CF6-80. Is this correctly reflected by placing 61 in the cfg file?The SFC of the Cf6-80 engine is .342 at sea level, but I don't have information for the cruise SFC, so I have make it around .41 to compromise.Thanks for any help you can give me.-AV

>I am trying to correctly model the GE CF6-80C2D1F engine. >Here is what the engine sections looks like in the >aircraft.cfg >>[GeneralEngineData] >engine_type=1 >Engine.0=10.666667,-26.833333,-5.500000 >Engine.1=-69.500000,0.000000,17.333333 >Engine.2=10.666667,26.833333,-5.500000 >fuel_flow_scalar=.82 >[TurbineEngineData] >fuel_flow_gain=0.002000 >inlet_area=61.000000 >rated_N2_rpm=32360.000000 >static_thrust=54700.000000 >afterburner_available=0 >reverser_available=1 >>Concerning the rated N2 rpm, here it is set to 32360, but >the actual maximum N2 rating on the CF6-80C2 series is >11,055 RPM. Does this need to be changed then? You can change it to most anything. It only affects a token RPM variable. So, I only see turbine RPM in real units on a test gauge. However, setting it low may affect the Hydraulic pressure, especially at lower RPM, since there is a table in the AIR file which sets that pressure as a function of 0 - 29920 RPM. I change the scale to make it more consistent with the RPM setting, though it's not critical.>I have the inlet area at 61 sq ft, the actual value for the >CF6-80. Is this correctly reflected by placing 61 in the cfg >file? Yes. --- And maybe No. Setting Inlet area about 10% larger than the area of the turbine intake fan is reasonable IF TBL 1507 in the AIR file is correct. That table sets 'Ram Drag', so higher Intake Areas reduce high altitude/speed thrust significantly. You can adust 'Inlet Area' to drop thrust at FL350 so it's appropirate. That could also set the N1 reading, higher Inlet Area requires higher N1/N2 to get the same thrust at cruise.>The SFC of the Cf6-80 engine is .342 at sea level, but I >don't have information for the cruise SFC, so I have make it >around .41 to compromise. >-AV SFC increases quite a bit in cruise. No turbine runs better than 0.55 there. I'd suggest setting fuel_flow_scalar=1.20 to get SFC=0.60. I know the older CFM turbines run about 0.64. By the time your AC is climbing at 10,000 ft, 280 kts, fuel flow will be reasonably close for most real AC. "Adjust Drag - Zero Lift" to get appropriate PPH in cruise. Typically 0.018 for jets. That comes to '37' in the AIR file. Otherwise, the 'parsite_drag_scalar' in aircraft.cfg will modify that value. The fuel_flow_scalar can be adjusted to get approprite flow in cruise, but will only agree with the actual SFC if drags are correct. Ron

Thanks for the great insights!-AV

It depends on how well you want to model the engine: The .air file contains the N1,N2 and thrust profiles for variation with temperature, altitude and Mach Nr.Have a look in:http://perso.wanadoo.fr/hsors/FS_Soft/index.htmlfor links to AirEd.ini and my engine turbojet notes in the Airfile design documentation files.I can send you a SS to convert the text dump of the .air file to graphs which will give you max. speed and ceiling data.Ian

what is the engine on? what aircraft you building?

This GE engine is used on MD-11F's, the aircraft I am building. You can see her at http://www.thescorned.homestead.com/md11.htmlI had been working on MD-11 flight dynamics for several weeks before I started the new visual model. I released a set of MD-11 dynamics here on AVSIM. You can find it by searching for my name: Albaro Villegas.Unfortunately I got practically no feedback on those dynamics, so I haven't tried to release any more updated versions. But I'm going to make new air and cfg files from scratch for this new model so I needed this extra info for that.Ian: I'd appreciate seeing those tables. I'd like to modify the air files so users can have about 28 - 107 percent N1's available to them. I'm already familiar with that wonderful program, AirEd, and I've been using that in conjunction with the Air file editor from www.aircraftmanager.com to edit my air files.

thats looking good. Look forward to flying her :D

I've been browsing through the various tables in the air file, and my brain is kind of fried afterwards. Are these tables pretty consistent with aircraft of the same class? (i.e. tables for widebody airliners will look similar). Or does each aircraft require it's own specially configured tables?Another quick question about flaps...if I'm not mistaken the flap area is set in the air file. For such aircraft such as the MD-11 with leading edge slats of x square feet in area and trailing edge flaps of y square feet area, do I include the total square area (x+y) in this value? Or is there a way to tell FS the seperate areas for each set of flaps? Thanks again for the help.-AV

>I've been browsing through the various tables in the air >file, and my brain is kind of fried afterwards. Are these >tables pretty consistent with aircraft of the same class? >(i.e. tables for widebody airliners will look similar). Or >does each aircraft require it's own specially configured >tables? >>Another quick question about flaps...if I'm not mistaken the >flap area is set in the air file. For such aircraft such as >the MD-11 with leading edge slats of x square feet in area >and trailing edge flaps of y square feet area, do I include >the total square area (x+y) in this value? Or is there a way >to tell FS the seperate areas for each set of flaps? Thanks >again for the help. >>-AV I thought I posted a reply but where is it:The Airfile forum is accessable in AvHistory 1% Airfile decodehttp://www.avhistory.org/cgi-bin/boards/Cf...ebbbs_config.pl or have a look at my engine papers at:http://perso.wanadoo.fr/hsors/FS_Soft/fsdocs.htmlIan Kerr

Oh well that link did not last. Has anyone found the new AvHistory site yet that actually works.Ian

Ian, I recall they are switching servers. They had a msg about it on Monday. It's avhistory.org now. It's upJulianPS: did you ever get my email via this board about the spreadsheet?

>Ian, >>I recall they are switching servers. They had a msg about it >on Monday. >>It's avhistory.org now. It's up >>>Julian >>PS: did you ever get my email via this board about the >spreadsheet? Hi Julian,Err, they servers TWICE this month and has no postings on the 5th. It seems it was back by just after midnight EST on the 6th and it's working again.Q2: no never got a notification of an e-mail via this board. Though I did get one about a reply on another thread once. Oh, I have to click on every thread - done. Now how the ********** do I reset my personal preferences. I probably have e-mails suppressed to avoid the spam porietial. Best to post questions on AvHistory.AirFile Board for me so we can have a quiet chat. I see you posted there on the 13 Dec but I was having a nice rest and did not chip in my 2

Hi Ian, It's funny about Avhistory, I keep switching the domain names from .org to .com. I hope it settles. Yes about F16 engine. You mentioned something about a spreadsheet. I'll post at AVhistory forum cause I can't change my email address on this board. Julian