Flugzeuge können nur fliegen, weil an den Tragflächenenden ein permanenter Druckausgleich stattfindet – die sogenannte Wirbelschleppe. Diese geht mit großen Kräften und Momenten einher, die während des Koppelvorgangs kompensiert werden müssen. Das macht den Prozess wissenschaftlich hochspannend.

Es ist ein Grundlagenprojekt. Wir betreten wissenschaftliches Neuland. Es müssen Lager konstruiert, Systemarchitekturen implementiert und Sicherheitsnachweise erbracht werden. Es gibt also noch sehr viel zu tun, bevor solche Verbünde beispielsweise Internet in entlegene Gebiete bringen.

Wir entwickeln die Grundlagen selbst und erarbeiten uns ein tiefgehendes Verständnis für Zusammenhänge, die auch über Verbundflugzeuge hinaus Anwendung finden können. Zudem ist die Perspektive reizvoll, eine Plattform zu schaffen, die bei Katastrophen Menschenleben retten kann.

‘Lego’ in the stratosphere: How intelligent aircraft networks are revolutionising communication security

Satellites are far away, expensive and inflexible. Aircraft, on the other hand, struggle with instability at high altitudes. A research team at TH Wildau, led by Prof. Alexander Köthe, is working on a visionary solution: ‘networked aircraft’. These unmanned systems are designed to fit together like Lego bricks in the stratosphere. The fact that this project is at the cutting edge of science is now also confirmed by the high-profile funding it has received from the German Research Foundation (DFG).

Imagine a natural disaster interrupting all communication in a remote area. Satellites are too far away or not optimally positioned, and conventional drones do not have the endurance to circle the site for days on end.

This is where the TH Wildau research project on formation and coupling control of composite aircraft comes in, which has also been funded by the DFG since 2025.

A knighthood for research at TH Wildau

Approval by the German Research Foundation (DFG) is more than just funding – it is a seal of approval. In engineering sciences, the approval rate for such projects is less than 25 percent. For universities of applied sciences (HAWs) such as TH Wildau, the hurdle is even higher: their share of DFG funding is well below 2 percent overall.

Prof. Alexander Köthe, who is leading the project, emphasises the significance of this success:

‘The fact that we were able to prevail in this competition underlines the scientific relevance of our project. We are conducting basic research at an international level, which is normally more likely to be found at large universities.’

The dilemma of extreme wings

This is what the project is about: in order to remain in the stratosphere (at an altitude of approx. 20 km) for months on end using only solar energy, aircraft need a huge wingspan and very low weight. But what is aerodynamically ideal up there becomes fatal when ascending through the turbulent troposphere.

Many previous projects have failed because the long, thin wings broke under the load of the gusts.

The Wildau team's solution: the composite aircraft. Several robust individual aircraft ascend separately and only dock together in the calm stratosphere to form a highly efficient and stable formation – ‘a bit like Lego bricks,’ says Prof. Köthe.

Multi-agent systems: swarm intelligence instead of supercomputers

The biggest technical hurdle is the moment of docking. When two aircraft touch in the air, enormous air turbulence occurs – known as wake vortices. To control these forces, the project relies on multi-agent systems (MAS).

In contrast to classic systems, in which a central computer controls everything, this decentralised approach treats each aircraft as an ‘intelligent agent’:

• Decentralised control: Each aircraft has its own controller and ‘thinks for itself’.
• Information exchange: The agents communicate wirelessly and exchange data on position and forces.

Fail-safe: There is no single point of failure. If a controller fails, the affected aircraft can be released from the formation while the rest continue the mission safely.

The mathematics behind precision landing

The project is initially focusing on mathematical modelling. The aim is to calculate flight paths (trajectories) that are as energy-efficient as possible. The aircraft must be guided precisely from above or below into the formation, as lateral movement is physically almost impossible.

A high-precision simulation environment is being created to validate the models. But Prof. Köthe and his research assistant Janik Hopf are going even further: they are planning experiments with small drones to prove the theoretical approaches experimentally.

Three questions for Prof. Alexander Köthe

What is the biggest challenge in mechanically coupling aircraft at altitude?
Aircraft can only fly because there is a constant pressure equalisation at the wing tips – known as wake turbulence. This is accompanied by significant forces and moments that must be compensated for during the coupling process. This makes the process scientifically fascinating.

How far are we from permanent deployment?
It is a fundamental project. We are entering uncharted scientific territory. Bearings must be designed, system architectures implemented and safety certificates obtained. So there is still a lot to do before such networks can bring the internet to remote areas, for example.

What fascinates you most about this project?
We develop the fundamentals ourselves and gain an in-depth understanding of interrelationships that can also be applied beyond composite aircraft. In addition, the prospect of creating a platform that can save lives in the event of disasters is appealing.

Background: Excellence through cooperation

To realise this mammoth project, TH Wildau is cooperating with international heavyweights.

The team includes Prof. Dr Steffi Knorn (TU Berlin), an expert in distributed control, as well as Prof. Carlos Cesnik (University of Michigan) and Prof. Bart Besselink (University of Groningen).

This collaboration also shows that Wildau is building the aviation of the future.

Further information

About the research group: CLICK