Hi all,A short question but probably without an easy answer...For my aircraft I have tweaked the aircraft.cfg file so that the fuel consumtion of the jet during cruise is very close to the real thing. When the aircraft is idleing on the ground however, is approximately twice that of what it is supposed to be !I understand that the fuel consumption is regulated in the .air file but how to change that ?I've purchesed and tried Airwrench but using that results in many many things not working anymore in the aircraft, so I'd prefer not to use that. AirEd doesn't allow me to change the graph that I pressure is the correct one, so what to do now ?Anyone ?Thx,Bj

How did you change the in-flight fuel consumption?

hi to all european onwers ....please post your average l/100km fuel consumption for the european cx-7 if possible city/highway/mixedand comments if u like......

Hi Bj

That's not the appropriate approach to correcting fuel flow.I asked what he changed because it's important to take the proper approach.

Hi guys,Sorry for not responding earlier, I was away from the computer for some days...The question WarpD asked was : how did you change the fuel flow ?Simply by setting a value in the aircraft.cfg file: fuel_flow_scalarIt's at 1.0 right now. But as you know changing this one will change the fuel consumption in all flight regimes and not opnly when the aircraft is at low rpms...Bj

That value sets what is normally termed thrust specific fuel consumption.If you know the TSFC value for the engines (you haven't told us what aircraft this is so I can't help further), then you would divide the TSFC by 0.5 and place the resulting value in that field in the aircraft.cfg file.Once that value is set correctly, the next thing you would want to check is to ensure the engines are idling at the correct N2 value. If that's correct, then the only thing left is to adjust the amount of thrust generated at a specific N2 value to obtain the correct fuel burns.

That value sets what is normally termed thrust specific fuel consumption.If you know the TSFC value for the engines (you haven't told us what aircraft this is so I can't help further), then you would divide the TSFC by 0.5 and place the resulting value in that field in the aircraft.cfg file.Once that value is set correctly, the next thing you would want to check is to ensure the engines are idling at the correct N2 value. If that's correct, then the only thing left is to adjust the amount of thrust generated at a specific N2 value to obtain the correct fuel burns.

Ed,1. Engine type: General electric GF6-502. The engines are indeed idling at more or less the correct N2 (approx 63% - should be around 65%).3. Fuel flow idle should be 1320 lbs/hour effective ff = 2350 lbs/hourBtw I tried the AAM idea and changing offset 1505 doesn't seem to have any effect whatsoever...Bj

You don't want to change TBL 1505, it deals with engine startup.TBL 1506 is the one you should be adjusting. Based on your fuel_flow_scalar you're setting a TSFC value of 0.50. That means that under ISA sea level conditions your engines should be outputing 1320lbs thrust each at idle (assuming the FF you stated was for both engines, if not then double it). The fuel flow you state the aircraft is actually using is showing engine thrust at 2350lbs per engine (still assuming the FF value was representative of a single engine, otherwise double it).TBL 1506 is a list of values where X represents the value of N1 and Y represents the percent of total thrust the engine produces at ISA sea level.

TBL 1506 is the one you should be adjusting. Based on your fuel_flow_scalar you're setting a TSFC value of 0.50. That means that under ISA sea level conditions your engines should be outputing 1320lbs thrust each at idle (assuming the FF you stated was for both engines, if not then double it). The fuel flow you state the aircraft is actually using is showing engine thrust at 2350lbs per engine (still assuming the FF value was representative of a single engine, otherwise double it).TBL 1506 is a list of values where X represents the value of N1 and Y represents the percent of total thrust the engine produces at ISA sea level.

So I set fuel_flow_scalar to 0.5, ff at idle is now correct. The thrust setting in the aircraft.cfg is also set correctly. So what to do next ?Sorry for sounding so ignorant but I have no experience in this field and I don't want to mess up the performance of my aircraft !Bj

I thought I had explained all this already... apparently I'm not doing a very good job at it.The fuel_flow_scalar sets the TSFC rate. I don't know what the value is for the engines on your aircraft. I tried to locate information regarding them on the internet, however they're so old there's absolutely zero information on them.1 - Set the fuel_flow_scalar value to get the correct TSFC.2 - Set the correct N1 and N2 values at throttle idle.3 - Set the correct thrust level in TBL 1506 for the idle N1 value to get the correct fuel flow.

OK, I got it to work now. There's only one strange thing left now: FSX seems to have a minimum fuel flow rate (now at 1360lbs/min), so the fuel flow is fixed at this low threshold when the engines are idling, in fact FF stays at this threshold up to paprox 25-26% N1. Bj

OK, I got it to work now. There's only one strange thing left now: FSX seems to have a minimum fuel flow rate (now at 1360lbs/min), so the fuel flow is fixed at this low threshold when the engines are idling, in fact FF stays at this threshold up to paprox 25-26% N1. Bj

Then your thrust level is incorrect for idle.

Which can be set where ....(yes I'm completely ignorant when it comes to FDE stuff)Bj

I already gave you a complete outline on how to accomplish everything you wanted to accomplish, including this. A couple of posts up.