ELLESAR – AROUND THE WORLD ON SUN AND JET STREAM
Students: J. Bliekendaal, F. Boutahri, G. van Diepen, D.R. van Hengel, D.A. Huffnagel, F. Smulders, W. Stikvoort, J.A.M.M. Wedershoven
Project tutor: ir. J.A. Melkert
Coaches: dr. S.J. Hulshoff, dr.ir. A.H. van Zuijlen
It has been an old challenge to travel around the world. First it was done by ship and now many attempts are made to circumnavigate the globe by flight. It is also true that the concept of ‘sustainability’ is becoming ever more important in all areas of life. To fly around the world using only sustainable energy sources is a true challenge which would demonstrate the potential of sustainable energy.
To do this using only the solar energy that is available during the day (as Bertrand Piccard is trying to achieve with the Solar Impulse) has been proven to be very difficult, because of the lack of sun during the night passages. The energy needed to sustain flight during these phases has to be stored in the aircraft resulting in a large weight. In turn this increases the required wing area and so on. Therefore an alternative method for achieving the flight around the world has been devised by incorporating the potential energy of the large wind gradients found high in the atmosphere. This potential is turned into useful lift and thrust by using two aircraft at different altitudes experiencing different wind speeds. These airplanes are interconnected by a cable. Especially in the region of the jet streams (bands of high wind speeds in the atmosphere) the amount of energy that can be obtained by means of this ‘airsailing’ principle can be impressive.
To complete the task of flying around the world on both sun and jet stream energy the design phase focused on a great number of aspects.
These include aerodynamic and structural design, stability and control, design of the electrical power system and propulsion units, as well as calculations with respect to the performance of the aircraft. The most important part, however, is the investigation of the air sailing concept. Using a special Excel sheet a strategy has been devised with which two aircraft could stay in the air throughout the night without using any power other than the wind gradient between them.
The paper of this project is available as a PDF-document here.