That's the vision pitched by the likes of Amazon, UPS, and DHL, and it's an appealing one.

Boeing has a different idea for delivery drones, one that's bigger by an order of magnitude. Last week, the aerospace giant revealed a prototype for an electric, unmanned cargo air vehicle that it says could haul as much as 500 pounds—that's 400 large Domino's pizzas or 11,291 newborn-sized diapers—as far as 20 miles. But this big buzzer isn't going to your house.

In fact, Boeing isn't quite sure where it's going. "It's a concurrent exploration of a nascent market and nascent technology," says Pete Kunz, the chief technologist for HorizonX, the Boeing skunk works-venture capital arm hybrid division that built this thing (the marketing team hasn't given it a catchy moniker yet).

A team of 50 engineers spent three months building what looks like a car-sized Erector Set, fitted with eight spinning blades (each six feet from tip to tip), and weighing in at an auspicious 747 pounds. It navigates and looks for obstacles using components and software provided by Near Earth Autonomy, a Pittsburgh-based company in which HorizonX invests.