Changing fuel tank usage order

[Landman]

Many months after downloading it I recently installed the Project Fokker F28. I noticed that the aircraft burns the wing tanks first then the fuselage tank after that. There are only three tanks in the aircraft.cfg - the left and right wing tanks and the fuselage tank. What do I have to change in the aircraft.cfg file or the .air file to make it burn the fuselage tank first then the two wings tanks simultaneously after that?

[rcbarend]

I noticed that the aircraft burns the wing tanks first then the fuselage tank after that. There are only three tanks in the aircraft.cfg - the left and right wing tanks and the fuselage tank. What do I have to change in the aircraft.cfg file or the .air file to make it burn the fuselage tank first then the two wings tanks simultaneously after that?
Are you talking about the fuel consumption by the engines in normal flight ?? (so APU Off, no fuel dump, no crossfeed).

If so: I think your observation is not correct : as you can see in the three fuel gauges, the engines burn an equal amount of fuel from the left, right and center tank simultaneously.
Which is standard behavior in FSX, and cannot be changed in the .air file / aircraft.cfg without specific fuel control gauges.

Just curious why you would want to change this order.

Regards, Rob

PS: All assuming of course you are referring to my FSX F28 package, which is the original ProjectFokker F28, made compatible with FSX.

[Landman]

Aha, I didn't notice it was burning from all three. I thought it was just the wing tanks. I wanted to make it burn the fuselage tank first because that's normally the way it's done in the real world. The reason is because the weight of the fuselage and whatever is in it like passengers, baggage, fuel, etc. places stress on the area where the wings join the fuselage while in flight. For this reason they normally burn the fuselage tanks first to reduce this stress. Some larger airliners don't even get their fuselage tanks filled unless they are on a long haul flight. I remember in the documentary about the crash of TWA 800, which was as 747, they said that the fuselage tanks were empty and only the wing tanks had fuel in them. Imagine holding a model of an aircraft by the tips of its wings. The wings are supported by your fingers but this does make them want to bend where they meet the fuselage. It is the same with aircraft in flight. It's not that much of a big deal but it does help the longevity of the aircraft to do it this way. Of course with a smaller aircraft like the F28 it probably does not make that much of a difference.

Thanks for updating this plane for FSX. I like it very much.

[Bjoern]

Fuel also adds a bit of stiffness to the wings, which also comes in handy.

And as Rob said, you will need a control gauge to make FSX use fuselage tanks first. Or manually switch between tanks if possible.

[rcbarend]

Hmm.... Interesting observations ....

First (knowing the guys who originally made these F28 models/FDE's): the tank content definitions in the aircraft.cfg are probably the real-world figures.
Meaning that appr. 75% of fuel capacity is in the left/right wing tanks.

So, given how FSX uses fuel from the tanks (as explained above), it's important how you initially load fuel.
If you only need max. 75% fuel for your flight, you can fuel up only the left/right wing tanks and no fuel in the fuselage tank.
And if you need more fuel for the flight (so also add fuel in the fuselage tank too), you have to reduce the max. passenger/cargo (== fuselage) weight because it will exceed the max. takeoff weight then.
Meaning that the balance between weight of the fuselage (increased by actual fuel/pax/cargo) and left/right wings remains in tact ......

Apart from that:
I WILL make an optional update of the package so that the fuselage tank is emptied first, instead of all tanks simultaneously.
If only because I like to specify/coding such stuff ..LoL; and it shouldn't be much effort since I allready manipulate fuel consumption for the APU .....

Cheers, Rob