Fuel left, erm, wrong!

[michael]

When I go into the in-flight report it says "Fuel remaining: 02:30" or something and then when I look half an hour later is says "Fuel
remaining: 03:00"

How can this be the amount of fuel remaining when its increasing be the second?

It there something wrong or is it a glitch?

[gronji2004]

No, FSP is constantly calculating your fuel depending on speed, height etc. Once you remain at a same speed and the same height, the
fuel burn will constant, and FSP will have an exact time for remaining fuel. Hope ya understand.

Regards,
Alex

[Joeflyer]

That's a good way of explaining it, Alex.

Certainly, the fuel remaining at the time you check it may be during the time you are at a lower altitude and higher power setting. Once in
the uppper flight levels and at a constant power setting, the fuel endurance will be much better. After all, jet engines are far more efficient
at high altitudes.

[michael]

But when I start it says 1:30 or something and just b4 landing i take a look and its on 4hrs or something!

[Joeflyer]

That's true, Michael. Remember my statement above? You may have full fuel tanks when starting out, but because the aircraft is at a low
altitude and high power settings during takeoff and climb, the fuel burn is going to be much higher, so if you kept the same power
settings throughout the flight, the endurance is going to be quite short. Once you have reached, let's say FL340, the air is far less dense
than at 12,000. Those jet engines start to "sip" fuel at that altitude rather than "gulp" it at 12,000 feet.

What you see on the FsP report is correct. Just be thankful that you don't see -1:30 or something like that

[gronji2004]

Joeflyer wrote:
That's a good way of explaining it, Alex.

Thanks Joe!

Dont forget the 45 Minute Fuel Reserve folks!

[Launchbury]

Partly correct - Indeed FSPassengers calculates range, but it is based solely on average fuel burn per hour and fuel remaining. When
you take off, fuel flows are going to be staggering. A Fokker 28 burns about 12,000 PPH (Pounds per hour) on the take off roll. and about
8,000 PPH in the climb. We'll call it an average fuel burn of 10,000 PPH. If I loaded 15,000 pounds of fuel (good for a 2.5 hour flight, with
reserves, etc.) then FSP, with its aggregate calculations, is going to tell me that with an average fuel burn of 10,000 PPH, I can fly for 1.5
hours. However, once I reach cruise altitude and reduce to cruise power, my burn rate drops to about 4,000 PPH. and the FSP-displayed
average fuel burn value will drop from 10,000 PPH towards 4,000 PPH. The longer you fly, the lower the value will get. It will never go all
the way down to 4,000 PPH since it uses an average from the entire flight, but might stabilize somewhere around 5,500.

Say I still have 11,000 pounds in the tanks and my FSP average burn has stabilized around 5,500 PPH, FSP will show a fuel endurance
of 2 hours. Any questions?

[Joeflyer]

Errm, Launch, you took the longer route to explain virtually the same thing. I had to keep it in simpler terms. You have to go and get so
dang technical

[Sakakawea]

Be a member in this forum, and you can skip any aviation university

[Valoran]

Ha ha, wouldn't that be nice!

[Joeflyer]

Sakakawea wrote:
Be a member in this forum, and you can skip any aviation university

Now why didn't I think of that before getting my BS at ERAU??