The Laddermill consists of a series of wings or kites all connected to a cable that forms a huge loop. Like the wings of an aeroplane will the wind cause an upward lift force to the wings. By changing the attitude of the wing (angle of attack with respect to the wind) the lift force be made larger or smaller.

The wings on one side of the cable loop are all placed such that they produce the maximum lift force, while the wings on the other side of the loop will give a much smaller lift that in fact is just sufficient to support their own weight and the weight of the cable.



The result is a large difference in force between the two ends at the ground. When the cable loop is guided around a wheel on the ground the force difference will drive the wheel. By connecting the wheel to a generator electricity will be produced.



The wind energy aloft has thus been transferred to electricity on the ground.



The KNMI, Dutch Meteorological Institute, has made available the wind measurements that are made by weather balloon sondes, which have been launched during the period 1951 to 1980 (noon and mid night). The launch site was De Bilt, a town in the centre of the Netherlands. The winds at lower altitudes, i.e. below 500 m, are therefore influenced by the roughness of the terrain. The upper winds are very much the same as would be found along the coast.



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