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.

未来，城市的天空可能属于无人机。这些蜘蛛形的飞行设备有四个或更多螺旋桨（因此常被称为四旋翼、六旋翼、八旋翼飞行器等），这些螺旋桨同时提供升力和推力。人们希望，未来自动飞行、自我导航的无人机将会提供从外卖披萨到运送乘客的各种门到门运输服务，不受地面交通拥堵的阻碍。

Delivering goods, and particularly people, to and from a battlefield is, though, a bit different. Aircraft have to be hardened against enemy action, and also need the capacity to transport large payloads. A flying spider is unlikely to cut the mustard. Instead, Lockheed Martin, the maker of one of the world’s best-known military helicopters, the Black Hawk, is working on a drone with those specifications—made from a Black Hawk helicopter.

不过，往返战场运输物资，尤其是运送人员，则不尽相同。飞机必须加固以经受敌方攻击，还要有运送大载重物资的能力。飞行蜘蛛不太可能符合要求。然而，世界上最知名的军用直升机之一“黑鹰”的制造商洛克希德·马丁公司（Lockheed Martin）正在研发一种由黑鹰直升机改造而来、能满足以上要求的无人机。