# FSNav calculations question

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First off, I know FSNavigator has their own forums but no one seems to answer over there when I knock on the door. Maybe they are over at the pub for a bit.Is anybody able to tell me the math formula used to get to the total fuel required in FSnavigator?IE: How are they coming up with the total for a particular aircraft.? They seem to be the only ones I can find that make it work. I want to make a Excel program that does weight and balance and I need to know what is done to calculate the total fuel required.Thanks for any help.

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The person to best answer the question is Helge Schroeder.But looking at the basic FSNav data I suspect its a very simple formula where FSNav breaks the flight into 3 segments; climb, cruise and descent.There are 3 separate fuel flow values for each, climbfuel cruisefuel, descentfuel. There are also 3 speeds for each segment climbspeed, cruisespeed, descentspeed.Climb speed and climbfuel is applied between the departure and the TOC point. The cruise fuel, and speed and applied between the TOC and TOD points. The descent fuel and speed is applied from the TOD to the destination.Use the climb rate, and the cruise altitude to determine how long it will take to reach the TOC point Once that is established the rest is easy.Example: (fsnav aircraft.ini file)[Airbus A319]climbspeed=240 (Kts)climbfuel=9000 (per hour)climbrate=1600 (feet per min)...Say the cruise altitude is 31000 ft. Divide 31000 by 1600 and you have how long it minutes it will take to reach 31000 ft.31000 / 1600 = 19 minsClimb fuel = (9000 / 60) * 19 = 2850The descent is exactly the same use the descentrate to determine descent time. For cruise use the cruise speed to determine how long in minutes it will take to fly between the TOC and TOD points.Regards.Ernie.

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