FLYING a helicopter is tricky, especially when hovering. You use your left hand to raise and lower the collective-pitch lever (to climb or descend), your right hand to move the cyclic-pitch joystick (to go forwards, backwards and sideways) and both feet to work the anti-torque pedals (to point the nose). At first it all seems like an impossible dance, but with plenty of practice and careful co-ordination it can be mastered. Flying a drone, by comparison, is easy-peasy. Some can be operated with little or no experience using only a smartphone app. So, it was a matter of time before resourceful folk started to think about building simple-to-operate drones that are large enough for people to fly in.

One passenger drone undergoing flight tests is the Volocopter VC200 (pictured above). With 18 separate rotors it might seem to be an ungainly contraption, but its makers, e-volo, a company based in Karlsruhe, Germany, claim it is more stable than a conventional helicopter. It is certainly more straightforward to fly and can be operated with just one hand. Twisting the joystick makes the Volocopter turn left or right and pushing an “up” or “down” button makes it climb or descend. To land, the pilot needs only to keep his finger pressing the down button until the aircraft is safely on the ground.

The idea behind the Volocopter and similar craft under development is that, like a drone, they are packed with sensors, including gyroscopes, accelerometers and magnetometers which, combined with an on-board computer system, means the aircraft flies largely autonomously. The pilot—or operator as they might more accurately be called—provides only basic commands, leaving the aircraft itself to take care of any necessary manoeuvres, balancing itself during a hover, automatically holding its position and compensating for changing conditions, such as a sudden cross wind.

The technology is sufficiently advanced that there is nothing to stop passenger drones taking to the air, provided they can meet the same safety standards as other light aircraft and are flown by trained pilots. At a price for a small machine likely to be similar to that of an upmarket car—and a fraction of the cost of a new helicopter—they could prove extremely popular in recreational and sport aviation.

The next step is to persuade aviation authorities that, because the craft are so heavily automated, they can be safely and reliably flown by people with only a little training. Convincing officials of that could take a few years, but it is possible. Aviation authorities have in the past worked with companies and flying enthusiasts to develop special training programmes for other new types of aircraft, such as powered hang-gliders and microlights.

Some envisage going further still, allowing passenger drones to provide autonomous air-taxi services. A bit like using an Uber app to call a cab, a pilotless drone would be summoned to whisk you away to your destination. That raises so many tricky questions, around insurance, infrastructure and public liability, that such services are many years away. But the journey to that destination may well have begun.

Unmanned drones can already be flown under existing guidelines. This week America’s Federal Aviation Administration (FAA) finalised its rules for civil drones weighing less than 55lbs (25kg). They must be kept in line of sight, below 400 feet (122 metres) and away from people. To use a drone for commercial purposes the operator must undertake an approved training course. Exemptions to the line-of-sight rule will be allowed for some flights, such as those making deliveries. But heavier drones need to be registered like conventional aircraft and face tougher regulation.

Let’s twist again

The attraction of drones is their ease of operation. Unlike most helicopters, hovering drones use multiple rotors. Many drones are based on a design called a quadcopter, which employs four rotors on arms set 90 degrees to each other. Each rotor is directly driven by an electric motor. By turning two of the rotors clockwise and two anticlockwise it counters the twisting effects of torque produced by a single-rotor helicopter (without a tailrotor to push against the torque, a helicopter would spin hopelessly round and round). Moreover, whereas a helicopter needs to vary the pitch of its blades (the angle at which they attack the air) in order to manoeuvre, the multiple rotors on a drone have a fixed pitch. The drone instead manoeuvres by independently changing the speed of one or more of its rotors under computer control. As this set-up requires fewer and less complex moving parts than a helicopter, it makes drones simpler, cheaper to build and maintain, and potentially more reliable.

Ehang, a dronemaker based in Guangzhou, China, is using the quadcopter design for a single-seat drone it is developing, but with an added twist. The Ehang 184 has a total of eight rotors, two on each corner but with one rotor facing up and the other facing down, each powered by its own motor. This builds in an extra margin of safety so that should a motor or rotor fail, the aircraft would still fly. Huazhi Hu, the company’s founder, aims to begin flight tests of the 184 in Nevada later this year to obtain an airworthiness certificate from the FAA.

Ehang’s eventual intention is that passengers need only enter their destination on the 184’s control screen, strap in and let the drone fly them the entire journey autonomously. The craft is designed to nip along at up to 100kph and fly for 23 minutes before its batteries need recharging. With existing battery technology, passenger drones are still a long way from beating conventional helicopters in both endurance and load-carrying abilities. But batteries are getting better. And even big aerospace companies, such as Airbus, believe that electric and hybrid power systems will be used in future passenger aircraft.

Flying chips

The 18 rotors lifting the Volocopter take the concept further. Ascending Technologies, a German dronemaker bought earlier this year by Intel, a giant chipmaker, gave e-volo a hand with the electronic systems that control them (the craft contains more than 100 microcontrollers). The greater number of rotors provides both more efficiency in lift and higher levels of redundancy in the event of a failure. And, just in case of a big emergency, there is also a parachute—one that will gently carry to the ground the entire drone with its passengers remaining in their seats.

The VC200 gained permission to fly from German authorities earlier this year. It has an all-in weight of 450kg and, in its present form, a flight duration of 30 minutes. After completing a series of flight tests the VC200 should be fully certified by 2017 in a category of aircraft known as an “ultralight”. The company have taken this route because it will get the VC200 into the air sooner and allow valuable flight experience to be built up while discussions continue about creating a possible new class of aircraft for passenger drones.

Apart from recreational flyers, other users might include the emergency services with, say, a paramedic flying directly to an incident without having to rely upon a helicopter and a professional pilot, says Florian Reuter, an e-volo director. A four-seater version, the VC400, is also planned along with hybrid versions that will be fitted with petrol-powered range-extenders. The ultimate aim, adds Mr Reuter, is for Volocopters to provide air-shuttle services in congested places, such as cities. With more experience of operating such flights regulators would be in a position to consider whether passenger services could enjoy complete autonomy.

A rather different approach is being taken by Malloy Aeronautics, a British company. It is developing a drone you can sit on like a motorbike. The Hoverbike is now in its third incarnation, having begun with two rotors, one at the front and another at the rear, but progressing to four. However, it does not look like a typical quadcopter. Instead, it has a pair of rotors at the front and another pair at the back. Each is slightly offset and partially overlapping. So far, the company is carrying out test flights of the craft as an unmanned drone in order to develop its software and systems fully before fitting a seat and handlebars to produce a passenger version. Malloy has, though, flown a one-third scale remote-controlled prototype with a dummy pilot (see picture below).