There will be plain fixed wing and soft wing designs, parasails, zeppelins, and oversized quadcopters and octocopters. As regulatory and certification demands are satisfied, airframes will carry donkey-sized loads over 80 kilometres in an hour.

Cargo drones are a supplementary transport system, not a disruptive one. You cannot move people by drone — not yet. They are pointless for last mile delivery of the kind envisaged by Amazon Prime Air and many other drone developers: in Africa, the last mile is a child walking to school with a backpack. Nor is it likely within our lifetimes that cargo drones will be competitive with the low cost of arterial road and rail transport. They are about the middle — a medium sized vehicle shifting medium sized loads medium distances between middle sized communities. To be seen to have value to the community and not be a threat, they will need to create jobs not just in the productivity gains they afford but in and of themselves. Loading and maintenance will be labour intensive. A donkey in the sky does not do away with a donkey on the ground, anymore than it negates the value of a motorbike, or a bicycle. But they can improve health and emergency services, connect markets, and grow industry in Africa at a critical moment in its history.

To match the massive scale of the Nokia 1100, donkeys will have to be built with fewer parts, less maintenance, and at a lower cost than any aerial vehicle yet conceived. The unit cost for a donkey will need to be close to the price of a decent Chinese motorbike in Africa. Several trends have converged to make this price point possible: mass production of parts for the smartphone industry foremost, but also pervasive cloud computing, new wireless data links, new powertrain technologies, local manufacturing and hacking, open source designs, and the rise of drone makers. Nevertheless, the combination of bargain price and space probe level performance remains an extreme engineering challenge.

Some assumptions need be met. The first is that donkeys can be made safer than manned flight. They will need to be capable of flying unmanned, without a pilot even on the ground, carrying the necessary redundant systems, and be able to land instantly and safely if a route is compromised. They will have to be able to deploy airbags and parachute solutions to slow and still a tumbling airframe in the event of failure. And they will need to do all this while matching the performance of organisations like the British charity riders.org which runs African health ministry motorbikes 50,000 kilometres over five years without a preventable breakdown. The second assumption is that donkeys can be built to be silent and beautiful in the sky, so that humans looking up from the ground will regard them either neutrally or with pleasure. Electric motors and noise cancellation will be required to achieve quietness: drones simply cannot drone.

What is it to be a beautiful drone? They might have a sheen and colours which can alternately hide them against the colour of the sky, or cause them to shimmer like a shard of the firmament. They might draw on biorobotics to imitate birds, dragonflies, or the drift of octopus underwater, in all cases avoiding settlements, moving along the rivers and the keeping to the edge of the jungle, freeing up land and nature. On every route, they will be less intrusive on the landscape than electric pylons and wind turbines.

This will take time and experimentation. Industry standards for donkeys will rely on technology transfer from industry as well as on invention and tinkering by young African engineers and hardware hackers. For the first routes, donkeys will be flown in groups to better deliver multiple units of blood, vaccines, and medical diagnostics. Their initial disappointing size will be limited by the battery technology and the need to prove to authorities that donkeys can be both safe and secure. The regulatory, security and insurance risks associated with cargo drones are significant. Government will have to have oversight of loading and be able to immediately drop down a donkey in case of security risks. However, the biggest hurdle to the technology is the emotional demand of having a donkey flying over your head. In this regard, I find it helpful to think about sky.