A series of design studies were performed to investigate the effects of flatback airfoils on blade performance and weight for large blades using the Sandia 100-meter blade designs as a starting point. As part of the study, the effects of varying the blade slenderness on blade structural performance was
investigated. The advantages and disadvantages of blade slenderness with respect to tip deflection, flapwise & edge-wise fatigue resistance, panel buckling capacity, flutter speed, manufacturing labor content, blade total weight, and aerodynamic design load magnitude are quantified. Following these design studies, a final blade design (SNL100-03) was produced, which was based on a highly slender design using flatback airfoils. The SNL100-03 design with flatback airfoils has weight of 49 tons, which is about 16% decrease from its SNL100-02 predecessor that used conventional sharp trailing edge airfoils. Although not systematically optimized, the SNL100-03 design study provides an assessment of and insight into the benefits of flatback airfoils for large blades as well as insights into the limits or negative consequences of high blade slenderness resulting from a highly slender SNL100-03 planform as was chosen in the final design definition. This document also provides a description of the final SNL100-03 design definition and is intended to be a companion document to the distribution of the NuMAD blade
model files for SNL100-03, which are made publicly available. A summary of the major findings of the Sandia 100-meter blade development program, from the initial
SNL100-00 baseline blade through the fourth SNL100-03 blade study, is provided. This summary includes the major findings and outcomes of blade design studies, pathways to mitigate the identified large blade design drivers, and tool development that were produced over the course of this five-year research program. A summary of large blade technology needs and research opportunities is also presented.