posted 06-21- 09:51 AM               

This comes through a series of interactions between physics entities. For a given airspeed there is, first of all, the drag of external stores. More importantly, though, a plane will need a higher angle of attack for a given airspeed to create sufficient lift to oppose the added weight, and an increased angle of attack in effect produces more drag on the wings, and this drag then needs to be compensated by more applied engine power, which in turn increases fuel consumption.

SDOE modells all of this.