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How is the endurance computed


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lhe
lhe
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A sample fuel plan computed by SkyDemon looks like this:

Taxi/Takeoff          4,2 ltr
Enroute      2h 17m  73,6 ltr
Holding Time    45m  18,5 ltr
Landing               2,5 ltr
Contingency (10 %)    7,4 ltr
Minimum             106,1 ltr
Planned       3h 8m 106,1 ltr


How is the endurance 3h 8m calculated? No time is given for the contingency fuel, but clearly it contributed to the endurance. At the fuel flow for the chosen power setting (31.7 l/h), the contingency fuel would contribute 14 minutes for a total of 2h 17m+45m+14m = 3h 16m – 8 minutes more than the total computed by SkyDemon. (The times for enroute and holding are correct.)

Am I missing something or is there an error in how SkyDemon computes the endurance? (If there is an issue with SD, now would seem a good time to address it as the fuel plan calculations are about to be reworked anyway to include Final Reserve Fuel.)



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grahamb
grahamb
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That figure is not endurance, but the planned amount required and the sum of calculated times for each of the various legs of your planned route based on the respective consumption and performance data in your aircraft profile. Tim can no doubt be much more specific on exactly how these legs are calculated.

Endurance is a calculation based on fuel loaded, not fuel required.
lhe
lhe
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grahamb - 7/26/2024 8:52:29 AM
That figure is not endurance, but the planned amount required and the sum of calculated times for each of the various legs of your planned route based on the respective consumption and performance data in your aircraft profile. Tim can no doubt be much more specific on exactly how these legs are calculated. Endurance is a calculation based on fuel loaded, not fuel required.

No, the amount required is given as "Minimum". The amount intended to be loaded (and thus the basis for the endurance figure) is "Planned".

grahamb
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lhe - 7/26/2024 9:20:49 AM
grahamb - 7/26/2024 8:52:29 AM
That figure is not endurance, but the planned amount required and the sum of calculated times for each of the various legs of your planned route based on the respective consumption and performance data in your aircraft profile. Tim can no doubt be much more specific on exactly how these legs are calculated. Endurance is a calculation based on fuel loaded, not fuel required.

No, the amount required is given as "Minimum". The amount intended to be loaded (and thus the basis for the endurance figure) is "Planned".

Apologies, you are of course correct. I misinterpreted what you'd written by not realising you'd set planned = required.

GO

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