Napoleon said that an army travels on its stomach, but today it's more accurate to say that it travels on a fleet of globe-spanning transport planes carrying ammunition, personnel, equipment, and all the necessities of life with an ease that would have been unimaginable a century ago.

The US Air Force estimates that transport aircraft consume 60% of its jet fuel. That's 1.2 billion gallons (4.5 billion liters) every year. To reduce this, the Air Force, along with NASA and the Defense Innovation Unit, is looking at blended wing aircraft as a possible solution.