sin αst

LIST OF ATTACHMENTSFURLING AND YAW ANALYSIS
Figure I.5: Potential energy of the tail and worked performed during furling. Both as a func-
tion of the furling angle �f
From the graph of figure I.5 it is seen that the work performed by the furling operation at a
wind speed of 13 m/s is less than the energy required to increase the height of the tail.
Hence the wind turbine will not furl at a wind speed of 13 m/s. At a wind speed of 14 m/s
the work performed and the energy required is approximately equal, which indicates that
furling is initiated at a wind speed very close to this, and certainly below one of 15 m/s
where the work performed is much greater.
210
I.3 Bearing contact pressure
The maximum contact pressure in the bearing is compared to the allowable contact pres-
sure.
Where
pdesign �
pdesign is the design stress from the load case
fk is the characteristic material strength
�m is the partial safety factor for the material
�f is the partial safety factor for the load
fk
� m� f
(I.29)