Long-term objective: Vision of a Danube flight
In 1811 Albrecht Ludwig Berblinger had the vision of crossing the river Danube from one bank to the other using his hang-glider. In the spirit of Berblinger, and continuing his vision, the city of Ulm aims to promote developments in general aviation that make it possible to follow the course of the Danube along its whole length from source to mouth (about 2.800 km), as free of noise and emission as possible with the aid of an innovative and environmentally sustainable aircraft, whereby this feat can also be completed in stages. The Berblinger Prize of the city of Ulm will initially be awarded in theoretical competitions for ideas that will particularly contribute towards reaching this goal.
Berblinger Competition 2013
In 2013 the city of Ulm was hosting another construction competition to develop and promote
ecological, long-distance flight, with the focus on innovative developments in the field of general aviation. The purpose of the Berblinger Competition 2013 was to explore theoretical
approaches, based on the latest research results, knowledge and developments in aviation, which could contribute towards achieving the long-term vision of a Danube flight from the source to the mouth of the river. We were looking for ideas for an innovative, manned aircraft or for individual components that can contribute towards the realization of this vision, so that a “Danube Flight” flying competition could become a reality within around 10 years. Aspects of environmental sustainability such as energy consumption, exhaust and noise emissions, play an important role in the evaluation of the submitted applications.
Award ceremony and winners
On 16th November, Lord Mayor Ivo Gönner presented the €25,000 Berblinger Prize as part of a public ceremony in Ulm's Rathaus.
The jury evaluated 21 entries. Since the competition was open to all imaginative and future-oriented applicants, the suggestions ranged from visionary pipedreams to practical and airworthy concepts.
The expert jury appraised the submissions according to the extent the objective had been met on the basis of the following criteria:
- Environmental sustainability 25%
- Future potential 20%
- Performance/effectiveness 25%
- Suitability for general use 10%
- Quality of documents submitted 20%
One result of the competition is the conclusion that as long as there are not batteries with a higher gravimetric energy density, there are only two alternatives to achieve an ecological long-range flight with motor gliders in the near future: purely solar-driven flight, provided that there is sufficient solar radiation, and a combination of electric and combustion engine which uses the benefits of both systems. These concepts also served as the basis for the proposals submitted by the three winners chosen to share the prize money.
According to the Berblinger jury, Stefan Senger from Holzheim/Germany submitted the currently best possible solution for ecological, long-range flight with engine-driven aircraft and was therefore awarded first prize and € 15,000. His proposal is a rock-solid concept suitable for general aviation use, relying on tried and tested components and systems. The combination of all performance characteristics in this concept promises to best fulfill the vision of a low-emission Danube flight. The approach presented is realistic, suitable for aviation, and optimally combines the advantages of electric and combustion engines. According to calculations, a range of more than 2,500 km can be expected. The concept is in such an advanced stage that its realization can begin (design, prototyping, flight testing and certification).
The core of this proposal is a hybrid-electric motor in which a motor generator with combustion engine supplies power to drive the electric propeller through interposition of a relatively small buffer storage battery. The motor driving the propeller sits in the aircraft’s nose. It only weighs about 7kg and has a continuous output of 20 kW. For better aerodynamics the propeller can be folded against the fuselage. This concept with the name of FES (front electric sustainer) originated with the Slovenian company LZ Design and was one of the highlights of the Berblinger Competition 2011. The motor generator has an output of 15 kW with a consumption rate of less than 5 l of super/hour, so a 35-liter tank allows 7 hours of operation. The high performance glider Antares 18 T from Lange Aviation was used for testing. Its motor box in the mid-section of the fuselage can easily house both motor generator and storage battery and the propeller drive can simply be mounted in the aircraft’s nose. The concept utilizes the high energy efficiency of liquid fuels and should therefore be able, adding together propulsion and gliding phases, without using thermal upwind, to cover a distance of more than 2,600 km. This equates to an average consumption of 1.3l of super per 100 km.
Second prize and € 7,000 were awarded to Eric and Irena Raymond from the USA for their project “Sunseeker Duo”. This two-seater solar glider is already being tested and represents the next logical step in the development of a solar-driven airplane. The project is characterized by the combination of many good ideas and a well-thought-through overall concept that is based on the designer's experience with solar aircraft during many flight hours. Under favorable weather conditions, an emission-free Danube flight is viable.
The two-seater design offers unique opportunities to further solar flight and promote scientific research for solar aircraft. Eric Raymond can teach other pilots during actual flight and not only through pre-flight instruction. As important, if more so, is the reserve for extra load that enables taking heavy measuring equipment instead of a second pilot on board. By doing so, new data can be gathered during real flight which directly contributes to the further development of solar flight without having to rely on simulations or to evaluate and interpret data post flight. With sufficient sunlight, Eric Raymond will surely be able to master an emission-free Danube flight with the purely solar-powered, electric engine of the “Sunseeker Duo”, not within one day, but without external or non-solar energy refueling.
Third prize and the prize money of € 3,000 go to Björn Drees from Ostelsheim in southwestern Germany for his ambitious concept for a two-seater canard aircraft. The project is still in the development stage and some questions are still to be answered. However, since the data presented move a low-emission Danube flight nearer to reality, the jury decided to financially support this project through prize money and to encourage the committed designer to continue his work.
They chose this concept of a canard glider because it implements a very simple drive system with a foldable propeller at the tail. In order to reduce the flight certification efforts, the plane was designed as an ultra-light aircraft. The main innovation of this contribution was the hybrid propulsion system, a combination of electric and combustion engines where both act in parallel on the propeller, but not simultaneously. This means that during cross-country flight the combustion engine operates using the high energy density of the liquid gasoline which – compared to a storage cell – can store large quantities of energy at low weight and therefore facilitate a long-range flight. It was designed for a 19kW-engine as installed in other ultralight aircraft, requiring 4 liters of Super 95 per hour. For takeoff and climb the electric engine operates, producing few emissions close to airports. The electric engine is fed by a LiPo-battery that is charged by wing-mounted solar cells. Altogether the hybrid engine presents a very ambitious concept.
All submissions are displayed in a roll-up exhibition opened as part of the award ceremony. The exhibition can be viewed until December 20th in the foyer of Ulm's City Hall. Furthermore it can be seen at the AERO trade fair in Friedrichshafen in April 2014. The Ulm Department for Culture will gladly receive requests for a presentation of this touring exhibition.