How is fuel flow calculated?

Just wondering, is the in-game FF calculated as lbs of fuel per hour? or what?

Thrust x Number of Engines x SFC.
Yes, I laughed too.

Sorry, but what is SFC?

Is it Specific Fuel Consumption?

Why not just take maximum fuel capacity / maximum endurance? To get fuel burn rate per hour.

EDIT: I'm pretty sure Concorde isn't twice as thirsty as the 744 - looking at the maximum ranges and fuel capacities. For instance (BTW I'm not a physicist, so please correct me if I'm wrong)... Concorde has a fuel capacity half that of the 747, it also has a range roughly half that of the 747. Therefore, shouldn't it's fuel consumption be roughly the same as the 747?

Concorde also travels twice as fast, so the burn rate over distance is the same, but Concorde burns twice as much per hour.
I believe fuel flow is per hour.

Ok, ye that makes sense.... but surely maximum fuel capacity / maximum endurance would find the FF rate?

I believe fuel flow is per hour.

Is that lbs per hour?

Concorde also travels twice as fast, so the burn rate over distance is the same, but Concorde burns twice as much per hour. I believe fuel flow is per hour.

I don't get it then, then why is Concorde so unprofitable still?

Concorde might use just as much fuel to get from A to B, but don't forget - it can only carry 1/4 the number of the passengers... Or 1/2 the number of passengers if you consider it can do twice as many rotations in the same time period.

Is that lbs per hour?

Not as far as I am aware.
SFCxThrustxEngines is the only way to reach the fuel flow number in AE, so we know it's wrong.
Range/Fuel capacity is, I agree, a better system.

well another way to get fuel flow is look at the FCOM of each aircraft. Though i don't think they specify fuel flow per hour and for which engines.

Thrust x Number of Engines x SFC.
Yes, I laughed too.

Whats funny?


In answer to the original question:
We use Thrust Specific Fuel Consumption, which is fuel consumed per hour per unit of thrust. Multiply that by the engine's thrust, and you get fuel flow per hour. Multiply that by the number of engines and you have a half-decent approximation, which is what is used in game. I imagine it was set that way as Thrust and TSFC can be far easier to come by than other data.
I am well aware that there's all manner of other things to take into consideration (differences at different stages of flight, amongst other things), and I am spending some time looking up other methods of calculation, but I doubt we'll see changes in some time.

I'm no engineer or mathematician, nor was I involved in setting up the maths that we have inherited here [I just ensure the numbers that go into them are accurate], but this is how the maths makes sense to me:

AE does this calculation:
(Total Fuel Flow) = (Engine Thrust) * [TSFC] * (Number of Engines)
which is:
(Total Fuel Flow) = (Engine Thrust) * [(Fuel Flow) / (Engine Thrust)] * (Number of Engines)
which cancels down:
(Total Fuel Flow) = (Fuel Flow) * (Number of Engines)
which suffices as an approximation for now


And that is pounds per hour, in answer to a question above.

Not as far as I am aware.
SFCxThrustxEngines is the only way to reach the fuel flow number in AE, so we know it's wrong.
Range/Fuel capacity is, I agree, a better system.

Fuel flow is not constant throughout a flight, and taking the range/capacity figure would have issues when you have a 777-200LR on a 1-hour flight.

The fuel calculations take into account climb, cruise, and descent fuel and prorate usage accordingly - it does not simply multiply fuel flow and flight hours together.

Still, by basing the fuel consumption entirely on the engines, there ends up with some huge discrepancies when you factor in aircraft weight. (A332 vs. 333, for example)
If max fuel/distance is not workable, then disregard it.
I suspect the next variable we may need to add is aircraft weight, which should fix issues with the use of the same engines within a family.

Aircraft-specific mass-based calculations are amongst the things I have been reading up on and playing with, with a view to incorporating into AE. This is what I was referring to in my previous post.

If they work, I may have calculations that will affect how range and airspeed are used in game also.

Out of interest....would this mean you got a slight fuel saving with a non-maxed plane?

In theory, yes

Ahhh fuel calculation uses the same method in which my name is steve explained in another forum. This is the method: The aviation gods (whom hold the sacred information) pass the info down to yuxi, and he passes it down to his minions, mainly britabroad.

I am new but so far am really impressed with the game setup! Is there a way to download spreadsheets with data concerning planes? Specifically, I'd like to see fuel flow alongside speed, range, etc. Thanks!

I am new but so far am really impressed with the game setup! Is there a way to download spreadsheets with data concerning planes? Specifically, I'd like to see fuel flow alongside speed, range, etc. Thanks!

Make your own. It's easy (but it does take quite a bit of time).