Amazon has unveiled the latest prototype of its Prime Air package delivery drone—and says it will be delivering soon, but gave no further details.

Prime time: The new aircraft, revealed at Amazon’s re:MARS conference in Las Vegas, is both more energy-efficient and safer than previous designs (not a bad idea if you plan to fly onto a customer’s front porch). Amazon says it tested 50,000 different drone designs in simulation before arriving at the new one.

Dual mode: As a test-flight video shows, it can fly in two modes, landing and taking off vertically and then shifting all six of its propellers in order to fly horizontally. Alphabet’s Wing has a delivery drone that does something similar, albeit using separate propellers.

Product placement: Amazon is apparently betting that drone delivery will someday, well, take off, and that this will transform the way products reach people. The company says the final goal is to have “fully electric drones that can fly up to 15 miles and deliver packages under five pounds to customers in less than 30 minutes.” It says it will make its first drone delivery “within months” but has not offered further details. And there’s no clue as to when a broader roll-out might happen.

Air traffic control: Although drones are being tested as a way to deliver organs and blood to hard-to-reach locations, aerial package delivery still seems a distant idea. It is unclear how such reliably such aircraft could navigate, or how they will avoid hitting things if they experience a malfunction. And it would be a big challenge just for a drone to work out where to land on an unfamiliar porch or front lawn.

New brains: Amazon is evidently working on these problems, though. Gur Kimchi, vice president of Amazon Prime Air, said in an interview that the new drone includes a vision and navigation system that lets it spot and avoid things like clotheslines and utility wires, as well as several systems designed to ensure trouble-free emergency landings.