Google co-founder Larry Page has been personally funding a pair of startups devoted to creating flying cars, according to Bloomberg Businessweek. Page has reportedly funded one startup, named Zee.Aero, with more than $100 million since its creation in 2010, and putting money into another, named Kitty Hawk, since last year. His interest in the companies is a personal ambition, says Bloomberg, and he even retained an office at once of the company's headquarters, where he was referred to pseudonymously as GUS — the guy upstairs.

Zee.Aero and Kitty Hawk have been developing designs for flying cars completely separately, says Bloomberg, with Zee.Aero conducting test flights of its prototypes at an airport about an hour's drive away from Google's Mountain View headquarters. Bloomberg reports that Zee.Aero has hired aerospace designers and engineers from organizations including NASA, Boeing, and SpaceX, and has been testing two single-seater prototype designs — one that looks like a "small conventional plane" and another with propellors dotted down its sides.

One of Zee.Aero's patents filed back in 2012. (Image credit: USPTO)

Previously known patents registered by Zee.Aero show a craft that matches this description, with a thin central fuselage and twin rows of propellors like outriggers. The patent, filed in 2012, says the aircraft is capable of vertical takeoff and landing (VTOL) and is described as a "safe, quiet, easy to control, efficient and compact aircraft." Not quite a flying car, then, but certainly a vision of personal aviation.

The other startup Page has been investing in, Kitty Hawk, has reportedly been building its own craft "that resembles a giant version of a quadcopter drone," according to Bloomberg's sources. The startup is smaller than Zee.Aero, and kept separate from its older rival. Some of its engineers come from AeroVelo — a firm that previously won the $250,000 Sikorsky Prize in 2013 for building a human-powered helicopter that can stay aloft for more than a minute (see the video below). And Kitty Hawk wouldn't be the first firm to design a quadcopter-inspired aircraft; similar concepts have been floated by Chinese firm Ehang and even built by lone engineers.

But as Bloomberg points out, the dream of flying cars has long been one that's dear to tech types, and so Page's involvement in these two companies is not that unusual. Numerous firms — such as Volocopter and Aeromobil — are developing aircraft built for personal use, although it should be noted that not all of these designs function as cars as well as planes. It's not clear, though, whether Page's involvement signals an increased seriousness in the personal aviation game, or whether this is just another billionaire looking for a fun new toy.

This autonomous drone can carry a human