Fuel planning/burn

[Groundbased]

I have searched the forums on this topic but haven't found anything that quite gives me the info I'm looking for.

Fuel burn will be affected by many things I'm sure, like type, flight profile, noise restriction and weather etc but I am trying to get an idea of the difference in fuel burn at varying weights. For example:

A 777-300ER at MTOW.
How much fuel in KG's will this averagely burn per hour?
If the take off weight was say 85% of the max what would the burn rate be then?

Clearly as weight reduces during the trip the fuel burn will change, but how do you take this into account for planning?

(I'm trying to design a basic fuel planning tool for use in sims)

Many thanks for any info

GB

[Intruder]

I don't know the 777, but the 747-400 with GE engines will burn about 3200 - 3400 Kg/hour/engine at cruise at max weight (390+ Tonnes), and decrease to 2400 - 2400 Kg/hr/engine approaching normal landing weight (250-300 tonnes), or 1700 - 1800 Kg/hr/engine at very light weights.

You could approximate it with a linear plot between those data points, then use an average over each 2-hour period based on that plot.