For the blade design, we used one of the links (see below [1]) from our section BB Learn page for insight into the factors that make up the blades. It explains that an attack angle of 15 degrees is ideal for the blade system, because any steeper of an angle begins to induce stalling (3). This seemed to agree with a few other sources on the internet, therefore we determined that 15 degrees is the best choice for a symmetrical blade design. The formula B=(80/λ2) was used to find the optimum number of blades, B, where λ is the tip to speed ratio (10). This reference states that this ratio should be between 5 and 8; in our design we used a ratio of λ=5. The resulting value of B was 3.2, which was rounded down to 3 blades for our system.
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