Fuel Draining out on a 747

dorianr · July 11, 2017

If anyone have a clue why the fuel it running out very quickly on the FSX 747, the fuel percent at full it run from 100 % to 80% in 20 seconds and buy the time you take off,you run out of fuel 0%. Fuel dumping is off and I check it on and off and it double the dumping when it's on.

Thanks for any tips

f16jockey_2 · July 11, 2017

Have you checked what the 100% actually stands for on your install?

In kgs, lbs, gals... whatever. Can be checked in the fuel/payload menu.

I suspect that somewhere down the road your aircraft.cfg was changed.

Wim

il88pp · July 11, 2017

Scatterbrain means if the fuel total capacity in the aircraft.cfg file has been changed and it is now only a very small amount, then the fuel will be used up very fast, and go from 100 to 0 % very quickly.

That is possible, but I don't think it's likely.

The fuel quantity is divided into several tanks.

That means a very small quantity can't be because of one single small typo.

Only after editing all tanks, all 8 of them, would the amount get that small that it is empty that soon.

If this is because of a typo when editing the aircraft.cfg file, then I think it's more likely a typing error in the

[TurbineEngineData]

section.

The value in the line:

ThrustSpecificFuelConsumption=

This is "at what rate is the fuel used", (at a certain fixed throttle setting).

If you increase this number and make it 100 times larger, the fuel probably gets used up a hundred times faster too.

And because it's just a single number, you could have accidentally changed that while editing.

In the default fsx Boeing 747-400, the value is:

[TurbineEngineData]

ThrustSpecificFuelConsumption = 0.40

Just in case you want to check if yours are OK, here's the default fuel tank sections as well:

I'll post it in a Code-box. May be hard to read in that, but copy what's in it and paste it in a .txt ile and it will be easily readable.

[fuel]
LeftMain  =   -96.0, -28.0, -4.0, 12546.0, 0.0    //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons) 
RightMain =   -96.0,  28.0, -4.0, 12546.0, 0.0    //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons) 
LeftAux   =  -112.0, -36.5, -3.0,  4482.0, 0.0    //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons) 
RightAux  =  -112.0,  36.5, -3.0,  4482.0, 0.0    //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons) 
LeftTip   =  -130.0, -73.0,  0.0,  1322.0, 0.0    //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons) 
RightTip  =  -130.0,  73.0,  0.0,  1322.0, 0.0    //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons) 
Center1   =   -83.5,   0.0, -7.0, 17164.0, 0.0    //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)
Center2   =  -193.5,   0.0,  6.0,  3300.0, 0.0    //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)

fuel_type = 2                                     //Fuel type: 1 = Avgas, 2 = JetA
number_of_tank_selectors = 1                    
electric_pump=1
fuel_dump_rate = 0.0167                        //Percent of max quantity per second, i.e. about 1 minute for full fuel

f16jockey_2 · July 11, 2017

Scatterbrain means...

Scatterbrain ??? Thanks mate... pun taken.

Dunno if it's ScatterbrainKid or me that should feel offended now.

Been a while since I saw him post btw...

But your general idea is correct.

I also suspect something like faulty fuel flow numbers, rather than faulty fuel quantity.

Just wanna be sure the initial fuel amount is OK, before diving into all other possibilities.

Wim

mrzippy · July 11, 2017

Been a while since I saw him post btw...
Wim

I tend to worry a bit when someone doesn't post for a while! I know he gets perturbed easily and will pout for up to a year or more! Hope it wasn't the 60 quid a week he was spending on cream tarts and gummy bears that got 'em??:eek:

Yer gettin' a little froggy there, il! Everything OK?

il88pp · July 12, 2017

f16, Sorry aboyt that!!! No pun was intended, honest mistake.

Had some very good conversations a while back in which the two of you helped me out. I think back when I started out making gauges. Maybe about evp too. So maybe that's why I confused your names. (Bad with names anyway, me.)

Doing good Zip, just chaotic here.

Anyway, all good mate, it's a lovely summer. I can't stop smiling.:D

Greetzzz Zip and f16jockey-2, enjoy!:pilot:

il.:cool:

dorianr · July 12, 2017

Thx. to il88pp il88pp

Top Gun

here are my config of the 747

the only thing I have done to the Config is an addition 747 Air Plane (Tanker) a 747 that went to Chile to fight the Forest Fire. I download here (fsim page) the only thing I did to the config is add the next (##) for that Air plane Code recognicion, then that was the Plane on wich I notice the problem with the fuel, it did run out quickly ( I delete the airplane) but now it does to the original 747 planes

[fuel]

LeftMain = -96.0, -28.0, -4.0, 300.0, 0.0 //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)

RightMain = -96.0, 28.0, -4.0, 300.0, 0.0 //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)

fuel_type = 2 //Fuel type: 1 = Avgas, 2 = JetA

number_of_tank_selectors = 1

electric_pump=1

fuel_dump_rate = 0.0167 //Percent of max quantity per second, i.e. about 1 minute for full fuel

[GeneralEngineData]

engine_type = 1 //0=Piston, 1=Jet, 2=None, 3=Helo-Turbine, 4=Rocket, 5=Turboprop

Engine.0 = -107.5, -69.5, -6.9 //(feet) longitudinal, lateral, vertical distance from reference datum

Engine.1 = -76.0, -38.9, -10.4 //(feet) longitudinal, lateral, vertical distance from reference datum

Engine.2 = -76.0, 38.9, -10.4 //(feet) longitudinal, lateral, vertical distance from reference datum

Engine.3 = -107.5, 69.5, -6.9 //(feet) longitudinal, lateral, vertical distance from reference datum

fuel_flow_scalar = 1.0 //Scalar for fuel flow efficiency

min_throttle_limit = -0.25; //Minimum percent throttle. Generally negative for turbine reverser

[TurbineEngineData]

fuel_flow_gain = 0.002 //Gain on fuel flow

inlet_area = 60.0 //Square Feet, engine nacelle inlet area

rated_N2_rpm = 29920 //RPM, second stage compressor rated value

static_thrust = 56750 //Lbs, max rated static thrust at Sea Level

afterburner_available = 0 //Afterburner available?

reverser_available = 1 //Thrust reverser available?

ThrustSpecificFuelConsumption = 0.40

[jet_engine]

thrust_scalar = 1.0

mrzippy · July 12, 2017

This is from the default 747-400: There is a big difference in number of tanks and usable gallons of fuel!

[fuel]

LeftMain = -96.0, -28.0, -4.0, 12546.0, 0.0 //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)

RightMain = -96.0, 28.0, -4.0, 12546.0, 0.0 //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)

LeftAux = -112.0, -36.5, -3.0, 4482.0, 0.0 //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)

RightAux = -112.0, 36.5, -3.0, 4482.0, 0.0 //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)

LeftTip = -130.0, -73.0, 0.0, 1322.0, 0.0 //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)

RightTip = -130.0, 73.0, 0.0, 1322.0, 0.0 //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)

Center1 = -83.5, 0.0, -7.0, 17164.0, 0.0 //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)

Center2 = -193.5, 0.0, 6.0, 3300.0, 0.0 //Longitudinal (feet), Lateral (feet), Vertical (feet), Usable(gallons), Unusable (gallons)

napamule2 · July 12, 2017

dorian,

Your cfg only has 600 gallons of fuel as compared to 'default' of 36,000 gallons. No wonder you ran out.

The quick fix is to add a '12' in front of the '300' and then you would have 12300 gallons in each tank which is close to default and would not mess up the load balance too much.

Chuck B

Napamule

f16jockey_2 · July 12, 2017

the only thing I have done to the Config is an addition 747 Air Plane (Tanker) a 747 that went to Chile to fight the Forest Fire. I download here (fsim page) the only thing I did to the config is ... etc..etc..

The only thing you have to do is to restore the backup the author of the addon surely advised you to make.

Wim

dorianr · July 13, 2017

Thank you.. I don't know why this was missing (I found a back config) this one and Paste it

my problem it's gone thanks again :)