Flying car was just a dream. Kittyhawk, the founder of Google, announced the closure.

Kittyhawk, an air taxi company backed by Google co-founder Larry Page, will close down, a setback to the long-standing dream of developing flying cars, Beijing time.

▲ Kittyhawk's flying car Heaviside

"We have decided to shut down Kittyhawk and we are still working on the details of the next step," Kittyhawk said on Twitter on Wednesday. Kittyhawk's technology is expected to continue in the form of a joint venture with Boeing, Wisk Aero. Boeing said on Wednesday that Wisk's operations would not be affected by the Kittyhawk shutdown.

Kittyhawk was founded in 2010 to create a market for so-called electric vertical take-off and landing aircraft (evtool). The secretive company is run by Sebastian Sebastian Thrun, a senior Google executive who has worked on Google's self-driving cars, augmented reality glasses and other projects.

Kittyhawk is one of several startups studying the concept of electric vertical take-off and landing aircraft, but it has proved to be more challenging than some expected. In recent months, air taxis have crashed many times during tests, raising concerns about their safety.