Originally Posted by
stupidhead
Well doesn't the aerodynamic shape and the weight kind of "anchor" the plane so that it doesn't get blown off course by some winds (and thus having to burn more fuel to stay on course of fly back on course)? i.e. when I throw a piece of paper vs. a full bottle of water, the bottle of water will likely travel farther and faster even though it's much heavier than the piece of paper.
One could argue that this effect cancels out the extra fuel burned.
The shape of the plane helps with reducing the amount of air resistance, but it does not help with the plane reaching and maintaining its cruising speed. As it is the speed of the plane (and the resulting lift forces) that keep the plane in the air, more weight definitely and absolutely causes an increased amount of fuel burn.
The paper versus bottle argument is also not the correct one... a piece of paper, folded into a paper plane, will go much further than a bottle of water, given the same amount of force.