Efficient, low cost blades for wind mills

The design and fabrication of and field experience with wind mill blades of a simple curved vane type are described. The skeleton of the blade is of a spar and rib structure and is made from mild steel pipe, rods, and T-sections. The required twist is given to the frame, and the blade surface is obtained by closely weaving the furniture-grade polythene canes. Various design factors affecting the final blade construction and improvements for increasing the life of the blade are discussed. The results of weathering tests on the blade material under accelerated laboratory conditions and actual field conditions are discussed. The cost levels of different blade materials are given for comparison