Consider a fictional aircraft with a fuel schedule similar to the following:
1st hour - 10,000 (lb or kg, doesn't matter) 2nd hour - 8,000 3rd hour - 6,000 4th* hour - 5,000 * and subsequent
As we can see the fourth hour of flight burns only half the fuel of the first hour, so fuel consumption is a function of time. Is the decreasing weight of the aircraft as fuel is burned the only reason for this increase in fuel efficiency, or are there other influences? For example if a jet launches with half tanks versus full tanks, would you use the same 1st hour fuel schedule?
I may be way off base here, so if there are fundamental errors in my question, please correct me.