The latest unmanned drone is a version of an existing manned one

Look! No hands... IN THE future, the skies of cities may belong to aerial drones. These are spiderlike devices with four or more propellers (thus often known as quadcopters, hexacopters, octocopters and so on) that provide both lift and thrust. The hope is that autonomous, self-guided versions of these will deliver anything from pizzas to passengers from door to door without being held up by terrestrial traffic jams. Delivering goods, and particularly people, to and from a battlefield is, though...