A huge autonomous drone that can carry the weight of two baby elephants has been unveiled by Boeing.
The heavy-duty quadrocopter can transport payloads up to quarter-of-a-ton, and Boeing says it may use the drone to shift heavy cargo in future.
After designing and building the craft in just three months, Boeing says it has already put the vehicle through flight tests at one of its research centres.
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The aerospace firm, based in Chicago, Illinois, calls the vehicle an electric vertical-takeoff-and-landing (eVTOL) cargo air vehicle (CAV) prototype.
It dwarfs the average drone, measuring 4.6 meters long (15 ft), 5.5 metres wide (18 ft) and 1.2 metres (4 ft) tall.
The cargo can be attached to the drone with cables.
Boeing says the drone is a precursor to its future autonomous flying craft.
'This flying cargo air vehicle represents another major step in our Boeing eVTOL strategy,' said Boeing chief technology officer Greg Hyslop in a statement.
'We have an opportunity to really change air travel and transport, and we'll look back on this day as a major step in that journey.'
Powered by an electric propulsion system, Boeing's CAV prototype has eight helicopter-like rotors, allowing for vertical flight.
The craft weighs 339 kg (747 lbs), but is capable of carrying a further 226kg (500 lbs) of cargo.
The quadrocopter has completed initial tests at a Boeing autonomous research laboratory in St Charles, Missouri, but the firm did not provide details of the flights.
'Our new CAV prototype builds on Boeing's existing unmanned systems capabilities and presents new possibilities for autonomous cargo delivery, logistics and other transportation applications,' said Steve Nordlund, vice president of Boeing's venture capitalist arm HorizonX.
'The safe integration of unmanned aerial systems is vital to unlocking their full potential.'
Boeing's made clear its interest in self-flying vehicles in October when it bought autonomous tech firm Aurora Flight Sciences.
Today's commercial airplanes already use sophisticated computer systems that have automated key aspects of flying.
But Aurora aims to go far beyond that, aspiring to a completely autonomous flight, from take-off to landing.
In April last year, Aurora was selected by Uber to develop its on-demand urban air transportation system.
