Design and Evaluation of Low-Cost Stainless Steel-Fiberglass-Foam Blades for Large Wind-Driven Generating Systems.

This report describes the development of a low cost wind turbine blade design based on a stainless steel/fiberglass foam design concept and to evaluate its principle characteristics, its low cost features, and its advantages and disadvantages. A blade structure was designed and construction methods and materials were selected. Complete blade tooling concepts, various technical and economic analysis, and evaluations of the blade design were performed. A study was made to determine the applicability of the blade design concept to various blade lengths in the range of 15 ft. to 200 ft. A test specimen of the spar assembly, including the root end attachment, was fabricated. This 20 ft. long full-scale section will be fatigue tested by NASA. It was concluded that the stainless steel/fiberglass-foam blade concept is a viable design for application to large wind turbine systems. A blade design was completed which meets the requirements for operation on the MOD-OA wind turbine. The design concept is applicable to various length blades. Blades less than 60 feet would use a stainless steel spar and blades of larger size would have a fusion welded carbon steel spar. The design permits a choice of a wide selectivity of air-foil shapes and, because of its modular construction, the design provides producibility and quality in high volume production.