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FSX Fuel problem....

M

Multipilot

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sweden
Hello,

I may be stupid but can anyone tell me if this is really correct?

I am looking in the Falcon 50 POH and it says that the FF (lb / hr) is 606 at a certain weight and temprature. The total usable amount of fuel is 15,514 lbs. That would mean that I could fly for 25 hours!?!? 15,514 divided by 606 = 25. That seems totally out of the ballpark to me. Am I calculating this wrong or what? This is taken from the all engine operating chart for long range cruise.

I figured it out.....606 x 3 :idea: (3 engines) = 1818 lbs 15,514 divided by 1818 = 8 hrs and that is more reasonable. :)

Regards,
John
 
Last edited:
Hello John

Jet engine fuel consumption varies a lot with altitude, temperature and of course power ("throttle") setting. You have the long range cruise figures which will be the economy cruise, and that will be at high altitude.

The fuel needed to get up to the cruising altitude would be significant. The result is a much shorter range than the "total fuel capacity / best fuel burn" figure suggests.

If you have the operating charts, take a look at the fuel burn at sea level and take-off power settings. I'd be interested to know.

Now you know why jets are not economic on short routes!
 
AlanWingnut said:
Hello John

Jet engine fuel consumption varies a lot with altitude, temperature and of course power ("throttle") setting. You have the long range cruise figures which will be the economy cruise, and that will be at high altitude.

The fuel needed to get up to the cruising altitude would be significant. The result is a much shorter range than the "total fuel capacity / best fuel burn" figure suggests.

If you have the operating charts, take a look at the fuel burn at sea level and take-off power settings. I'd be interested to know.

Now you know why jets are not economic on short routes!
Click to expand...

Thanks for the info but I already know that fuel is needed for taxi, climb, cruise, descent, holds, reach your alternate and extra 45 or 30min depending on IFR or VFR flight. ;)

The fuel burn figures at sea level are unavailable, I guess that is included in seperate fuel charts or something; oddly enough I see that they are not included in any of my handbooks here?!?!?

I do have fuel used figures for descent and holding.

I also have the power settings for take-off run and first segment climb up to 5,000' and the power settings vary depending on SAT C. But at 15 C SAT with a pressure altitude of 0' the Side engines are set at 89.0% N1 and the center engine 90.0% N1 this is without ice protection. The Indicated N1 may differ from the quoted values by +- 0.6%

I only have FF figures from FL 35,000' - 49,000'. Long range cruise and IND. MACH 0.75 and IND. MACH 0.80....I also have for MMO operations.

Regards,
John
 
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