Statics

STRESS FROM WIND GUSTS

In 1995, inventor Gerald Wurz and producer Norbert Kautzky applied for a patend on a SunSail with a closed cable circulation system. The cables are pre-tensioned with an open stainless steel spring, which has since then become a visual trademark. In 2009, SunSquare presented their new interior cable circulation system, featuring the "compensator". 

This patented closed cable circulation system guarantees that an equal and maximum stress of 350 N is channeled through the cabling. In the compensator (1) two pneumatic pumps tension the left (2) and right (3) cables independently. When wind gusts occur, the four pneumatic pumps provice 1.6 m of travel for the cabling to ensure the forces introduced remain at a maximum af 350 N. Additionally, the system compensates for the unequal extension and retraction lengths of the sail (5) and the cable drum (6).

In an extended state, the wrapping diameter on the sail (d) is approx. 20 % less than the cable drum diameter (D). Theoretically, while retracting the motor must achieve the torsional point at which the extended sail diameter is equal to the cable drum diamter. The 40 Nm Somfy motor need not contribute a further torsional point in order to safely retract the sail due to wind gusts. This is the significant difference between SunSquare's ans all other sail rolling systems, which must additionally overcome the forces within the cabling.