This is the Black Hornet. Its Norwegian manufacturer, Prox Dynamics, bills it as the world’s smallest military-grade spy drone, with a weight of 16 grams and a length of 4 inches. Propelled by two helicopter blades, the Black Hornet carries little more than a steerable camera that records still and video imagery. (That is: It’s unarmed.) Now British soldiers have brought it to Afghanistan, as it fits in the palms of their hands. It’s supposed to be a drone for an Army of One.