Rotating Umbrellas

Werner Sobek, Stuttgart/Germany, with Transsolar, Stuttgart/Germany

Structural engineering:
Werner Sobek, Stuttgart/Germany

Planning time:
1997 – 2003

Construction time:

This is a spokeless fabric umbrella whose fabric membrane is opened by the tensioning effect produced by the rotation and the resulting centrifugal forces. The umbrella mast remains fixed. An electric motor mounted in the mast head drives the membrane which is lightly reinforced in the hub area. The fabric membrane is not flat. Its shape is calculated from the span/fabric weight/rotational speed ratios using computer programs specially written for the purpose. These result in pagoda-like cross-sections providing an optimal stress distribution in the fabric. A lightly piped edge improves the aerodynamic stability.