Let’s just think back ten years – hardly anyone could have imagined that Teslas would be part of the common street scene and could easily break combustion engine performance records. Today, practically all manufacturers have electrically powered vehicles on offer or have announced them specifically. Time has passed quickly, it seems. Just like in a flash.
If we now look ten years into the future of aviation, there are good reasons to assume that we will take electric aircraft for granted and that they will look considerably different than we are used to today. Who would have thought in 2008 that we would be flying electric e-air racers? And who can imagine today that we will be flying electric passenger drones in 2030?
In lectures on this topic, the audience usually comes up with a mixture of “the batteries are too heavy, the range is too short, this will never fly or is much too expensive”. In unison: “It won’t happen that fast.”
It is a human phenomenon that we perceive time retrospectively as having passed very quickly. We massively underestimate what will be possible in the distant future (~10 years) and overestimate the possibilities of small time periods (~2 years). It is very difficult for us to imagine how the future will look like. But technical developments are predictable in a certain way, because technologies build on each other, accelerate each other or make each other possible in the first place.
Predictability, however, ends at so-called tipping points: disruptive changes in systems that have not announced themselves. The Corona crisis is one such example. A pandemic in itself was generally to be feared, but who would ever have thought that it would be possible to bring air traffic to a de facto standstill within a few days?
Climate change is another example. So far we have had a hard time with restrictions on climate protection. When changes are slow and invisible for a long time, with so little that is tangible, we find it difficult to change our behavior. This is despite the fact that the effects are clearly interpolatable for the future and that, here too, exceeding a tipping point (e.g. 1.5°C annual average warming) will make disruptive changes such as the thawing of the permafrost soils irreversible, as this process will trigger an unstoppable chain reaction.
Corona And Climate Chance
The global corona pandemic, on the other hand, has brought aircraft movements to a virtual standstill within a few days. It is therefore possible. In order to counter climate change, we – each of us, but also the aviation industry – will have to make our contribution, taking into account all aspects of climate protection, globalization, the desire to travel and economic viability, so that the measures and their effects are accepted. The electrification of the engine is one aspect of making aviation more climate-friendly. And the electric drive offers many more advantages than just CO2-neutral flights!
New Design Concepts Through Distributed Propulsion Systems
The electrification of the engine opens up the design space of aircraft construction in fascinating dimensions and enables innovative and creative developers to design completely new aircraft types. With propulsion systems in places that were unthinkable until recently and where even pilots cannot see at first glance in which direction the aircraft are flying. Let’s do the test using the example of Lilium Jet: Is the aircraft flying away from us or towards us?
In this rendering the Lilium Jet flies towards New York, the direction of flight can be recognized mainly by the shape of the winglets. The unusual engine configuration (36 impellers!), the duck wings and the missing vertical tail make it difficult to identify the flight direction. This configuration, by the way, could neither be realized with fossil propulsion nor could it be flown by human hands. 36 thrust levers, thrust vectoring, the missing stabilization of a fin and the aerodynamically complex transition from vertical to horizontal flight exceed human capabilities. 36 individually controllable impulses with a fossil propulsion system would not be synchronized mechanically anyway.
The Design Is The Serf Of The Propulsion
An aircraft design has always been the slave of the engine concept. This makes it clear that an electric or hybrid-electric drive system allows the basic concept of an aircraft to be constantly rethought.
The Eviation Alice is another example with an unusual propulsion concept that has distinct aerodynamic advantages. The propellers on the wingtips, which are freely inflated and deflated, would not be feasible with heavy fossil propulsion systems.
On the other hand, however, this reconfiguration of the drive system alone enables massive efficiency gains; the improved efficiency of the overall drive system would simply no longer be possible even with the costly further development of piston or turbine drives.
On the website Transport-Up you will find an extensive collection of different projects of future aircraft. If even a fraction of the developments shown there actually “gets to fly”, we will be able to marvel at completely new silhouettes of aircraft in the sky. But if the airspace is occupied by all these new aircraft – what kind of background noise can we expect?
With all the new possibilities of drive, materials and design – physics cannot be outsmarted. If electric vertical take-off aircraft are considered, the noise pollution can be roughly estimated on the basis of the propeller circular area load and the blade tip speed alone. Large, slow-turning propellers have a clear advantage here. A Lilium Jet is perhaps not only coincidentally on all its YouTube videos with pleasant music instead of real background noise. In comparison, the Volocopter has already flown in front of spectators and was “surprisingly” quiet. So we can expect that VTOL (Vertical take off and landing) concepts with relatively low wing loads/revs are drowning in today’s everyday noise of a big city. If we still assume that these aircraft take off and land in densely populated mega-cities on the roofs of high-rise buildings, the distance from the noise source should already be so great that these aircraft are no longer of any acoustic significance. In addition, there are creative ideas to eliminate the noise at the source by “directed counter-noise” (similar to the active noise cancelling in pilot headsets).
Electrically powered fixed-wing aircraft can be considerably quieter than their piston or turbine counterparts, if only because of their practically silent engine. The primary source of noise is the propeller and its placement on the fuselage: when exposed to laminar flow, it will be quieter than a pusher that has to work in the fuselage vortices. A propeller positioned above the wing or on the vertical tail can benefit from the noise shielding properties of the wings. This is where clever design is required to find a compromise between static, aerodynamic and acoustic needs. Even a mixture of an electrically driven and thus low-noise take-off phase and then conventionally driven cruise flight can have a strong influence on the perceived noise level on the ground.
Outlook: What This Means For Pilots
In the near future, powerful electric or hybrid drives will be available for aircraft. This will open up design space in fascinating dimensions. For fixed-wing aircraft as well as for vertical take-off aircraft. Or all mixtures of these.
About The Author – Morell Westermann
Morell Westermann is a futurologist, engineer and pilot. As Senior Partner of Future Matters AG in Zurich, he analyses the mega-trends of the next ten years. In doing so, he examines the various technological developments that will shape our society in the future. Morell Westermann is an expert on aviation, electric mobility and digitization and shows ways to a CO2-neutral society. At congresses and conferences, Morell Westermann discusses the convergence of these developments and mega-trends. He can regularly be seen at events and congresses as a keynote speaker, moderator and expert on Swiss television. His blog on electric mobility in everyday life is accessed by several thousand readers every month. Westermann has been a guest on several occasions at the largest German-language podcasts on electric mobility.
This article was also published in German.