Between two worlds

Envisioning the future of air transport means thinking with creativity and imagination while maintaining a high degree of scientific accuracy, says Bauhaus Luftfahrt Executive Director Mirko Hornung.

05.2016 | Text: Denis Dilba

Text:
Denis Dilba holds a degree in mecha­tronics, is a graduate of the German School of Journalism, and founded the Substanz online business journal. He writes articles about a wide variety of technical and business themes.

For decades, visions of the future have repeatedly portrayed weird and wonderful air­craft that resemble rays, arrows, or even flying saucers. Yet today’s planes look much the same as they did at the dawn of com­mer­cial air travel. When is that going to change?

Prof. Mirko Hornung: The question we should be asking is: does it have to change at all? It makes sense to develop new air­plane configu­rations only if they offer signifi­cant advantages over the conven­tional design. That’s why planes still look much the same today. So far, other configu­rations haven’t proved so much better that they would be worth implementing. If we’re talking about enhancement of just a few percent, we can usually achieve this through continuous improve­ment. It also has to be said that the industry hasn’t been idle either. While air­craft exteriors might not appear to have changed much since the Boeing 707, the interior is quite a different story. Over the past seven decades of commercial air flight, we have made substantial improve­ments to our air­craft. In that time we also reduced fuel consumption by almost 70 percent compared to the very first pas­senger jets, like the Boeing 707.

What research priorities and tech­nological develop­ments do you see defining the industry over the next two decades?

Hornung: All forecasts indicate that the number of air­craft is set to triple by 2050. The targets have been set—lowering CO2 emissions by 75 percent, signifi­cantly reducing nitrogen oxide emissions, and lessening noise—and give rise to a wide range of topics. Air­planes are only one piece of the puzzle; air­ports also play a role, as does fuel supply and the trans­port system as a whole. One driving force will certainly be the continued develop­ment of energy and propulsion systems. This area shows highly promising tech­nological approaches that we are exploring in close collabo­ration with MTU Aero Engines. For instance, we have recently been looking into new cycles, so-called composite cycles, in which different thermo­dynamic cycles are combined in order to once again dramatically improve engine efficiency. There still seems to be a lot of untapped potential here. Electric-hybrid propulsion systems—that is, a combination of electric motor and internal combustion engine—are of course also a topic for us. Only a few years ago, people were saying there’s no way they can work in a larger air­craft. But the idea no longer sounds quite so absurd.

“It makes sense to develop new air­plane configu­rations only if they offer significant advantages over the conven­tional design. That’s why planes still look much the same today.”

Professor Mirko Hornung, Executive Director Research and Technology, Bauhaus Luftfahrt e.V., and Professor of Air Transport Systems and Aircraft Design at the Technical University of Munich

Wait a moment, are you saying that electric-hybrid propulsion systems can work in larger passenger air­craft?

Hornung: In theory, yes. But it’s something that has to be exam­ined very closely. It’s been proved that in principle it would be possible. One of our main tasks now is to look at how we need to develop the individual components and tech­nologies; in other words, what has to happen if electric-hybrid propulsion systems are to represent an advantage when operating air­craft. Right now we still lack an adequate under­standing of the necessary components, such as batteries, generators, electric motors, and modified turbo components.

You also mentioned that airports and flying-related infra­structure need to be further developed, too.

Hornung: That’s right. For instance, we are currently looking at ways to improve air­craft ground hand­ling activities and their inter­action with the terminals and the air­port infra­structure. This also depends on future air­craft sizes. Another topic, in particular for mega­cities with ten million inhabitants or more, is how to get air­ports closer to the city center. Nowadays they are usually miles out of town, so most of the journey from door to door is spent getting to and from the airport. Yet in cities this size, ground transport is notoriously slow. Overall, this means that on shorter and medium-haul routes, flying is becoming a less attractive option. What can we do to change this situation? One key driver here will be noise reduction. Making air­craft quieter is the only way to increase acceptance for airports that are located closer to residential and busi­ness areas and can be reached more quickly.

Professor Dr.-Ing. Mirko Hornung

Professor Dr.-Ing. Mirko Hornung Executive Director Research and Technology, Bauhaus Luftfahrt e.V., and Professor of Air Transport Systems and Aircraft Design at the Technical University of Munich

Mirko Hornung (44) was appointed Chair of Aircraft Design in the Department of Mechanical Engineering at the Technical University of Munich in 2010. That same year, he also became an Executive Director of Bauhaus Luftfahrt. As a scientist and lecturer Prof. Hornung focuses on conceptual air­craft design, air­craft integration and evaluation. He studied and received his doctorate from the Department of Aeronautical Engineering at the University of the Bundeswehr (Federal Armed Forces) in Neubiberg near Munich. His dissertation on reusable space transport was awarded a research prize in 2003. Until 2009, he worked at EADS (now Airbus), where his respon­sibilities included the preliminary develop­ment of future air transport systems.

Wouldn’t one way of reducing noise simply be to develop aircraft that can take off vertically? Like the Harrier jet?

Hornung: The short answer to this is yes. But you can’t cheat physics. You still have to generate the thrust for vertical take-off, which produces a high level of local noise and also consumes signifi­cantly more kerosene than conven­tional takeoffs and land­ings. A vertical takeoff would have to be able to hold its own against present-day solutions in terms of both eco-friend­liness and economic viability. For this reason, no one considers it feasible for the mass market.

Some of the concepts you are elaborating at Bauhaus Luft­fahrt will never see the light of day—or at least not as originally intended. I can imagine this can lead you to question the point of it all.

Hornung: This is indeed a subject that comes up regularly. Our ambition is not to say this or that will or must be the next product. We want to explore new tech­nologies and under­stand where their potential lies for air travel. We then com­municate these findings. In this way, we create awareness for them and offer food for thought—outside a company’s normal develop­ment environ­ment. Our job is to show that there are still a lot of issues in aviation that are as yet unresolved. But also that there are pos­sible solutions out there.

“We want to explore new tech­nologies and under­stand where their potential lies for air travel. In this way, we create awareness for them and offer food for thought—outside a company’s normal develop­ment environment.”

Professor Mirko Hornung, Executive Director Research and Technology, Bauhaus Luftfahrt e.V., and Professor of Air Transport Systems and Aircraft Design at the Technical University of Munich

Wouldn’t it be better for the companies concerned to find these solutions themselves?

Hornung: Testing out ideas within the company context is extremely difficult. As soon as you investigate a new tech­nology and communicate it to the outside world, everyone jumps to the conclusion this is going to be that company’s next product. It’s actually a feasibility study, which doesn’t necessarily have anything to do with a pro­duct. You have to make a clear distinction. Some­thing else we find time and again is that it is much easier for independent and auto­nomous research institutions to enter into dialog with sectors from which tech­nologies could be adopted or modified. This is because such institutions don’t have a vested interest the way corporate entities do.

Devising innovative problem-solving approaches requires you to examine the issues from many different angles. Does this mean that Bauhaus Luft­fahrt has to draw on a whole variety of experts?

Hornung: This is precisely what we do. We work with a really colorful mix of experts: social scientists, ethno­logists, economists, geo­graphers, engineers from various disciplines, phys­icists, analytical chemists. They all contribute their scientific expertise and their own pers­pective. This, incidentally, might initially have nothing to do with aviation. What they all have in common, however, is their ability to work scientifically, under­stand technologies, approaches, and theories in their own area of expertise, and transfer these into another context.

What does that mean exactly?

Hornung: The team analyzes social trends, socio-economic constraints, and scientific publications on new tech­nologies. It then tries to understand and evaluate them, and examine what ramifications they may have on air trans­portation. For in­stance, what pos­sibi­lities does a given tech­nology with such and such core character­istics offer you? Is there a problem area in aviation where it could be mean­ingfully used to create value, provided it meets certain criteria?

“I have to admit I’m constantly leaping back and forth between these two worlds. It’s one thing to have an idea—in a spontaneous creative process. It’s quite another to examine its plau­sibility and its potential; in other words to decide what you can actually do with it. That’s hard scientific work.”

Professor Mirko Hornung, Executive Director Research and Technology, Bauhaus Luft­fahrt e.V., and Professor of Air Trans­port Systems and Air­craft Design at the Technical University of Munich

So, on the one hand you have to think freely and creatively and recognize tech­nological ap­proaches and conceivable ap­plications at an early stage. At the same time, you have to analyze what pos­sibil­ities the current state of the art offers with a high degree of scientific accuracy …

Hornung: … and that’s precisely the challenge. I have to admit I’m constantly leaping back and forth between these two worlds. It’s one thing to have an idea—in a spontaneous creative process. It’s quite another to examine its plau­sibil­ity and its potential; in other words to decide what you can actually do with it. That’s hard scientific work. It’s extremely challenging—­but also very exciting.

Can you give us a current example?

Hornung: Energy recovery in engines using thermo­electric elements. We became aware of this tech­nology some years ago and took a closer look. It was interesting, but very low efficiency ratios rendered it practically useless for ap­plications in air­craft. However, our analysis did show that if such thermo­electric gen­erators, which are capable of producing electricity from waste heat, were ever able to achieve higher efficiency coefficients, then things could get exciting. And this is exactly what has hap­pened over the past few years. A recent study conducted as part of the German aviation research program has revealed that this method of energy recovery could in fact make a contribution today. You simply have to get over the “it’ll never work” mentality. Everyone said the Geared Turbofan™ engine would never work either. Too complex, too expensive. It’ll never be tenable; it’ll never be approved. Now we can see that it does work: it’s flying. So the barrier can be overcome.

In your example, developing those tech­nologies until they were usable happened over a longer period of time. Isn’t it possible that one day air­craft might, after all, look very different than they do today?

Hornung: As I said, if a tech­nology emerges that justifies a change, then yes. Electric or hybrid pro­pulsion systems could bring about a dramatic change in an air­craft’s layout. But until then we still have to over­come considerable tech­nological hurdles. Perhaps there are other tech­nologies that we don’t even know about at the moment. But I can promise you one thing—we’re keeping our eyes peeled.

Bauhaus Luftfahrt

Founded in 2005 and head­quartered in Taufkirchen near Munich, the non-profit association defines itself as an inter­disciplinary think tank for the future of mobility and air travel. The association’s team of around 50 natural scientists, humanists, and social scientists elaborates comprehensive future scenarios and models for the European aviation industry. In this, it cooperates closely with industry and science—­albeit independently and in the public interest. Bauhaus Luftfahrt is sponsored by the Bavarian Ministry for Economic Affairs and the Media, Energy and Tech­nology, as well as by the Airbus Group, IABG, Liebherr Aerospace and MTU Aero Engines.

MTU Newsletter
MTU Newsletter

Receive regular updates on excellent service and top technology “made by MTU” with our newsletter, which also features a range of topics from the wider world of aviation.

You may also be interested in these articles:

Better flight connections

11.2016 | Dealing with the increase in worldwide air traffic between urban centers calls for new, quieter aircraft and more efficient airports. Big data applications also help get passengers and luggage to their destination more quickly.

“We also have to rethink our behavior”

11.2016 | Innovations in aviation primarily target the reduction of fuel consumption and emissions. But that might not be enough, says Prof. Marion A. Weissenberger-Eibl from the Fraunhofer Institute for Systems and Innovation Research ISI.