A very interesting innovation – the Electric Jet
We are all familiar, of course, with conventional jet aircraft propelled by fossil fuels. A interesting new development has recently been presented by a German company: the Lilium Jet. The jet is named after German aircraft pioneer Otto Lilienthal, and is claimed to have an all-electric range of 300km, with a 300kph speed.
Other interesting features are on-demand summoning of the jet – they especially envision it as an on-demand taxi service, for example, that can be summoned by a single click on a cellphone app. Of course, being all-electric, the noise levels should be quite low as well.
OMG not another doomed flying car
Nope. It isn’t. And that’s a good thing. As opposed to several similar “flying car” concepts we have been hearing about – some of them, depressingly enough, for decades already – this is a true jet, not a propeller-driven craft that cannot decide whether it’s a car or a airplane, and looks exactly as confused. It’s simply a VTOL jet aircraft and it looks real good – it even has gorgeous gull-wing doors. In fact, it is a whole bunch of jets: a multitude of little electric turbines, tiltable, giving the jet not only ample redundancy, but also true VTOL capability. As opposed to tiltrotor designs (think: osprey) it’s an elegant, sleek design. Starting up, the craft gains altitude and once a sufficient and safe altitude has been reached the jets gradually rotate back to their normal position and forward motion is obtained. At this point the aerodynamic lifting principles of normal aircraft wings take over and, as the turbines tilt further to their normal position, the craft accelerates to normal operational cruising speed – up to a quite comfortable 300kph.
The greatest innovation is of course the fully electric jet engines. The principles are the same, with the exception of course of a “missing” fossil fuel (kerosene) combustor. There’s the intake fan, obviously, the compressor stages, and then the directly coupled turbine stages which are driven by an electric motor. Obviously they are all on the same common shaft – just like in a conventional jet. The result is, just as it is with a kerosene-powered jet, forward thrust. What I find interesting is that the engineers have succeeded in creating sufficient thrust in the compressor and turbine stages without the considerable boost the kerosene combustor creates in a normal jet engine. Nevertheless this is one of the reasons why many little jet engines are needed – the trust per engine is probably not that extreme. But that doesn’t matter that much since they are light, simple and compact.
Redundancy equals availability; Simplicity equals high reliability
The beauty of this system is its simplicity. In comparison to existing concepts, Lilium Jets require no gearboxes, no foldable or variable pitch propellers, no water-cooling, and no aerodynamic steering flaps. Just tiltable electric engines.
Since they can provide differential thrust from the engines in cruise flight, no stabilizing tail is necessary. Basically that amounts to vector-thrusting capabilities: unheard of in conventional civilian aircraft.
The Lilium Jet engines have only one moving part – the central shaft of the rotor holding both the fan in the front and the magnets of the electric motor. This ensures highest reliability in operation and low maintenance costs of the propulsion system. The high redundancy of the system allows large inspection intervals to keep costs much lower than for helicopters or reciprocating engines.
The system can still do a vertical landing with a loss of multiple engines. This philosophy of redundancy has been applied to all flight systems. For a VTOL jet, weight is of course even more important than for normal winged aircraft. The whole structure of the jet is made from carbon fiber. Carbon fiber is five times stronger and three times stiffer than aluminum.
The designers of the Lilium Jet foresee (eventually) full autonomy: the pilot, eventually, will be a computer built-in. Hopefully it’s not running Windows, was my first thought, but a dedicated, smart and highly secure OS. But the concept does allow for very interesting innovations, of course – just as it does with cars. The difference, obviously, is that inherent safety standards and redundancy need to be on a completely different level. But I have little doubt that it is very much possible.
The first proof-of-concept flights have been successfully completed somewhere in April.
We are odd – and brilliant
All in all, a very interesting concept. We humans are a remarkable (and remarkably odd) species. One side of the medal is that we are literally unlimited beings: we can realize almost anything – make the impossible possible – as long as we commit. The other side is that the future holds many promises, provided, of course, that the world isn’t blown up first by a nasty fat gerbil beset with a severe case of megalomania, acting as a tin-horn dictator, or a bunch of completely deluded frothing-at-the-mouth bearded buffoons.
Read more about this interesting topic at: https://lilium.com/