61 Johannes Conradi Kippenberg-Gymnasium Schwachhauser Heerstraße 62-64 28209 Bremen Germany jo.conradi@t-online.de>
The Unrealised Potential of a Kite
J. Conradi, B. Akkermann, F. Sievers
Kippenberg-Gymnasium Bremen, Q1e Lk Mathematik, Projekt P5
Background:
In recent years a lot of research has been conducted on the conversion of the traction power of kites into electricity. Kites can be flown with different manoeuvres, the most common being the lying eight. This paper analyses which manoeu-vres produce the most traction power and therefore, the most electric energy.
Methods:
In order to determine the most efficient method of traction power generation a 6 m2 surf kite was flown at wind speeds averaging 19 knots. The steering of the kite was proceeded by a conventional bar with four lines. A force sensor was at-tached to the “chicken loop” during the loop and lying eight manoeuvres. Measurements were taken every 0.4 sec. for each manoeuvre. The average of 6 runs for each manoeuvre was calculated and compared. The recorded data was ana-lysed using Microsoft Excel for Mac 2011.
Results:
The measurements show that more power was exerted by a loop manoeuvre in comparison to a lying eight manoeuvre.
The average power for the loop was 1193 Newton and for the lying eight 1012 Newton. This translates into an increase of 17.83%.
Conclusions:
It can be concluded that the use of loops in producing electric energy is more efficient than the lying eight. The difference between these two manoeuvres can be explained by the fact that during a loop the kite has a constant directional change and during a lying eight the directional change alters always. For that reason the kite could gain more speed, which is relat-ed to the power. Another explanation for the different values could be seen that flying circles keeps the wing more centred at the maximum power point (zero azimuth angle). A lying fig-ure of eight is wider and the wing spends comparatively more time at positions towards the sides of the wind window (i.e. at larger azimuth angles). The instantaneous traction pow-er decreases towards the sides of the wind window and so does the average.
Further research is needed to develop kites and equipment, which can provide this manoeuvre. Due to the limits of this study further research is required to gain more data.
