NZFF

I'm engaged in a thread in the dreamfleet support forum about fuel planning as it relates to the 727. It's a bit of a chicken and egg thing, and none of us that have jumped in so far can come up with an answer that would work in the real world. Maybe someone with real world experience could tell us how it's done ?

Here's the gist of the problem ...

(1) To work out fuel requirements you have to know your fuel burn rate.
(2) To work out fuel burn rate you have to know how high you'll be flying.
(3) To work out how high you'll be flying (if you want to fly at optimum i.e. cheapest altitude) you need to know your gross weight.
(4) To work out your gross weight you need to know how much fuel you'll have on board.
(5) Goto (1).



Cheers
Gary

ps - I think I've posted this in the right place, it's about the sim but it's looking for a real world answer. Feel free to move it if I'm wrong.

Hey

If want more fuel for longer flights - just select unlimited fuel. Its handy if your doing long GA flights like me accross the pacific.

Jim

Usually I think you'd have some sort of documentation with the aircraft which would give you a base reference of fuel consumption vs. altitude.

Something like this...


Copyright of this is held by Aerosoft

Alex

f you were doing this for real then the flight manual would have all the necessary charts. The pilot would be given his zero fuel weight, you would know how far it's is from A-B and then it's number crunching.
I have charts for the 747-200 and you can start with a fuel flow chart for whatever cruise speed you want and it will give you your fuel flow per hour based on temperature at altitude. Mr Boeing has very kindly shown on the graph how high you can fly for a particular weight so there is your starting point.
There are also charts for the step climbs, 1 engine and 2 engine inop diversions etc.
It does get complicated to manually flight plan as there are many considerations such as fuel burn has a direct affect on weight which has a direct affect on power required which has a direct affect on your fuel flow....there's your problem again.
To get around this you know what your weight is at a particular point and you know roughly your fuel burn to the next point which gives you your weight at the 2nd point and then you can use a weight in the middle to go back to the charts and get a fuel burn over that part of the flight. You then do that for each part of your route.
Other considerations for the 727 are ETP(2) and ETP(D) which is equi time point between your departure to a point where you have an engine failure or presurisation failure and then divert. It's likely the fuel requirements for these problems would exceed your fuel requirements for a normal flight.

Of course it's all computerised now. Hope this makes sense.

Alex, your Cheyenne charts look much easier to work with than my 727 charts !

Here's a sample of one of the cruise charts for the 727-200. There are two other cruise charts, plus a holding chart, two climb charts, a descent chart, then there is the same again for the -100 ...



As you can see, gross weight is very much part of the equation.

Cheers
Gary

(maybe one of the mods should move this into the General FS forum since that's the direction it's heading )

You're right the chart isn't that helpful, however there seems to be enough to start with.
If you give me your zero fuel weight from FS and where you want to go I'll try and work you through it.

Cheers

PS Using a mid weight at FL330 I get a fuel burn of around 8500lb/hr. How does that compare to your aircraft? It seems a little light for 3 JT8's but then again it is in the cruise.