Hello all,I'm currently working on a combination of aircraft.cfg and .air file tweaks for the Project Airbus 319 and PSS panel.While I am generally satisfied with cruise performance (fuel burn/real TSFC values,, ~3 deg nose up attitude at FL370 [though I'm trying to maybe nudge it down to 2 deg if I can figure out how]), etc), two parameters Im trying to wrestle are ground thrust and fuel burn at idle/low power settings. I'm also trying to reduce the tendency for the aircraft to climb out initially at over 7000 fpm but that's a different thread I think.I'm expecting the A32x to burn about 800 lbs per engine at idle and have to apply a bit of thrust to break the wheels away from friction. Currently, each engine burns about 1100 lbs and can run away at about 25 kts on idle thrust.While I am new to .air file configuring. I have tried altering the 0.0000 Mach column of table 1506. I have also read http://forum.avsim.net/topic/254738-change-fuel-consumption/page__p__1630490__hl__idle__fromsearch__1#entry1630490. I have watered down some of the lower N1 values and saw some reasonable thrust/fuel burn rates...until I took off and got to cruise. I instantly noticed the engines were very very rapidly chasing speed, every second or two. Also N1 on startup would now sure to over 90%, unlike previously where it would gradually creep up to 30% during start (starting in about 25-30 sec, like I would expect a CFM56 to do). Additionally, only changing the first data column of 1506, my fuel burn was lowered to about 4500 lbs/hr total at cruise and able to maintain Mach .78 only at 55% N1 at FL370 at about 130k lbs GW.Am I missing something here or does the Mach 0.0 entry of 1506 really impact that many variables? Comparing my two .air file versions, the entries in 1506 are literally the only thing I have changed. I am using 0.002 as a fuel flow gain, 0.99 as the fuel flow factor, and 25700 static thrust in the aircraft.cfg.Any help would be greatly appreciated, thank you so much.Thank you very much.

My first guess... you chased a lot of wrong values and totally screwed up the FDE.Fuel burn rate is controlled by a single value. One. How much fuel is used based on thrust levels is a table. How much thrust is generated based on throttle is yet another table.

My first guess... you chased a lot of wrong values and totally screwed up the FDE.Fuel burn rate is controlled by a single value. One. How much fuel is used based on thrust levels is a table. How much thrust is generated based on throttle is yet another table.

Ok, then. Let's start with the basics so I (and anyone else who might need help that is reading this thread) can understand how to approach this problem.I will pose this question then in an attempt to get more specifics:Is 1506 not a table that outputs a thrust factor based on current Mach and N1? Is this not a place to start for friction break out thrust?

Sure, but it's not the source of why things are going wrong.As I've stated, there's only one value that affects fuel burn rate. Based on your post I'd say you changed quite a few things to get the engines to burn at the correct fuel rate.All of the variables are 'interactive'.

The following are is literally the only numbers that have changed between my working cruise .air file (with high idle taxi speed/fuel burn) and my working idle .air file (with "chasing" engine parameters at cruise). I have done a side-by-side comparison of the two, and this is the only difference. The below are the new values that are causing me problems.Record: 1506 *!Turbine Corrected Thrust Factor vs CN1 and Mach No.columns: 5 rows: 250.000000 0.000000 0.000000 0.000000 10.000000 0.001155 18.000000 0.000000 20.000000 0.020000 22.000000 0.030000 25.001560 0.058000 35.000000 0.115000 40.000000 0.152211 45.000000 0.199987 50.000000 0.254155 55.000000 0.315822 60.000000 0.388451 65.000000 0.474542 70.000000 0.540759 75.000000 0.625649 80.000000 0.744829 85.000000 0.798679 90.000000 0.911546 95.000000 1.015507 106.000000 1.020321I have removed the other columns for simplicity.

If that's how you're trying to set fuel burn rate... you're doing it wrong.Look, for the purpose of a simulation... TSFC is constant. Set that correctly before ever touching anything else.Also, I can't possibly imagine why you have 5 columns of data... seriously??

Ok, no need to be abrasive. I'm not looking to be heckled or criticized, I am here to learn specifics. Set fuel burn aside. Assume it is set correctly. Again, with my original .air file, fuel burn is exactly where I want it at cruise. I suppose I should be more pointed and specific with my questions.Let's focus on friction break away. (Yes, 5 columns is what originally came with the model). Is this first column, for 0 Mach if I understand correctly, what I should be adjusting for watering down idle taxi thrust and increasing friction break away?The impact of solely changing that column on engine thrust chasing I suppose is another topic.

Ok, no need to be abrasive. I'm not looking to be heckled or criticized, I am here to learn specifics. Set fuel burn aside. Assume it is set correctly. Again, with my original .air file, fuel burn is exactly where I want it at cruise. I suppose I should be more pointed and specific with my questions.Let's focus on friction break away. (Yes, 5 columns is what originally came with the model). Is this first column, for 0 Mach if I understand correctly, what I should be adjusting for watering down idle taxi thrust and increasing friction break away?The impact of solely changing that column on engine thrust chasing I suppose is another topic.

I'm telling you that your approach is flawed from the start. You're not going to achieve proper behavior unless you do things the correct way. If that's "abrasive"... so be it. It's also cold, hard fact.

Then please, by all means, detail the correct way. Set TSFC, then what?You also did not answer my question in my previous post.

Then please, by all means, detail the correct way. Set TSFC, then what?You also did not answer my question in my previous post.

As Ed told, its not easy, nearly impossible, since one doesnt have anything to work with then the TSFC setting.When you have enrything perfect, drag, typical cruise drag, engine power etc.. then you will find on the ground its way off.Nothing to do abaout it. That means nobody found a solution yet.On the break away, there are two ways to go: enhanced sim1.dll, with less friction, or adjust the lower regions in 1506.If you raise the 1506, you might lower the ramdrag a tad to compensate in descend.

Thank you for the info, I appreciate the help.I will start by adjusting only the 0 mach values under 30% N1

Thank you for the info, I appreciate the help.I will start by adjusting only the 0 mach values under 30% N1

I suspect you're still going to have problems, you didn't set TSFC correctly (based on your prior posts).There is exactly one location to set it... fuel_flow_scalar in the aircraft.cfgMessing with fuel_flow_gain changes engine spooling which you probably shouldn't be messing with. To correctly set TSFC fuel_flow_scalar should be set to TSFC*0.5. So if the engines have a TSFC of 0.65 then fuel_flow_scalar would be 1.3.

The CFM56-5B6/3 I am trying to simulate has a TSFC of 0.3276. So, 0.6552 is now the fuel_flow_scalar.What do you recommend next?

The next part is harder. You have to do a lot of flying.If you have performance tables that tell you altitude/speed/fuel flow... then you need to take the plane up and determine what those values are at given altitudes in the tables. Compare them and adjust table 1506 until you get the correct fuel flow levels. Once that's done... if your speeds are wrong, you need to adjust the drag/efficiency to correct.Once that's done, check to ensure the N1 to N2 ratio is correct at idle. If it is, then adjust thrust so that it's output is slightly below the aircraft's weight at 50% load. That should give you a better thrust behavior on the ground. As for break-away... you aren't going to win on that one at all. The ground friction behavior in FS is serously flawed.