Why is my default B737-800 consuming so much fuel?

[durkheim]

I have just completed a flight from Sydney to Brisbane using the default Qantas B737-800. Upon arrival at the gate, I noticed that my left and right fuel tanks were completely empty and the centre tank had 32.4% of fuel left. I had filled up 50.9% of fuel in each tank before leaving the gate in Sydney and I am curious as to why the B737-800 had consumed so much fuel . Could it be due to the long taxi from the domestic terminal to 34R in YSSY or the steep rate of climb to 35000ft ?

P.S. I seem to encounter similar problems with other default B737-800s but not the B747-400.

[torkermax]

It's due to the unrealistic fuel burns of the default 737 model.

[mrzippy]

Default fuel burn ain't great as torkermax stated. Long taxi shouldn't affect it greatly but steep climb...maybe. Standard AP vertical speed is usually 1800 feet a minute. Are you doing a steeper climb than that and what kind of throttle setting? And then if your tanks are full at takeoff there's all that extra weight climbing with you to fl350.

[mgh]

Apart from the fact that there isn't a default Qantas B737, what was the FSX fuel burn in pounds and what value did you expect?

[Adam24]

Apart from the fact that there isn't a default Qantas B737, what was the FSX fuel burn in pounds and what value did you expect?

There are repaints

[mgh]

There are repaints

Then it's no longer default. The .cfg file has changed.

[Adam24]

Then it's no longer default. The .cfg file has changed.

Yeah, but the flight dinamycs are the same in all repaints, unless an addon air file is used.

[mgh]

Yeah, but the flight dinamycs are the same in all repaints, unless an addon air file is used.

There are variables in the .cfg file that affect aircraft performance - eg in this case thrustspecificfuelconsumption, and fuel-flow_scalar. A default aircraft is one exactly as provided by Microsoft. Any changes make it non-default.

[tvieno]

Perhaps the the OP should've added the disclaimer that he used the default B737_800 created by Microsoft with a third party texture which may or may not affect the flight dynamics.

But I will think outside of box and try to address the OP issue. There are two schools of thought on getting the fuel consumption right for the default B737-800. In my view, they both work equally well regarding fuel consumption.

Open the plane's aircraft.cfg and change one of two but not both values.

Change the:
ThrustSpecificFuelConsumption = 0.6

to
ThrustSpecificFuelConsumption = 0.34

or change the:
fuel_flow_scalar = 1.0

to
fuel_flow_scalar = 0.74

This thread explains some of the findings: http://www.flightsim.com/vbfs/showth...-fuel-problems

[CaptainTower]

Durkheim asked a valid question. Torkermax gave him a straight answer. Tvieno told him correctly how to fix that unrealistic fuel consumption. Most everything in between was just nonsense about Durkheim's reference to this Qantas Boeing 737-800 as being default.

When I download new textures for my default aircraft, I look for something like "Repaint of the default B738" or whatever the aircraft might be. Just copying those new textures to a folder and adding the necessary lines to the aircraft.cfg file do not change the flight dynamics, and obviously, that was what Durkheim started the thread about. It will not help Durkheim to tell him to try the Orbit 738 and see if you get better fuel burn with that one. The two aircraft are the same - they are default FSX Boeing 737-800 aircraft except for the paint job. They both are using the same flight dynamics; they will fly exactly the same way. Why waste the man's time telling him Qantas is not a default livery? Do you honestly think he doesn't know that? We all know that Microsoft did not include Qantas as a livery; Microsoft has never included any real world liveries. Stick to the topic; help him like Tvieno did.

Thank you,
Tim