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aa1-45003

                 Very high performance airfoil blades

- ultra high lift-to-drag ratio and lift coefficient
- low fouling, very high performance, linear airfoil
- developed especially for small wind turbines
- capable of tip-speed-ratios of greater than  6:1
- developed at University of Illinois low speed wind tunnel
- program development by Dr. M. Selig
- 6063 T6 aluminum, precision thin wall extrusion
- rib reinforcements are located by design at axis of rotation
- high stiffness, low weight, optimized for variable pitch applications
- suitable for cutting into short blades for many-blade rotors
 
Note:
1) Three blades is the optimum configuration in the aerodynamics community; among DIY enthusiasts there are as many opinions as there are people - and some are very innovative. We encourage all.
2) one issue is not contestable - a high efficiency airfoil is profoundly important in small scale turbines. Only these exhibit high lift forces with drag forces dropping to less than one one-hundredth of the lift force.....sheet metal blades cannot compete.
In small scale turbines, low Reynolds No. values hinder good design. You need to take every advantage.....and, airfoil efficiency is the major one.

   - Shaped and cupped sheet metal blades, although loosely categorized as airfoils, are grossly inefficient under all circumstances and offer tip-speed-ratios of approximately 1:1(see technical discussion). They will go around, but that is it.
   -Only high efficiency airfoils, such as ours, can achieve tip-speed-ratios of 6:1 in the three blade configuration. Simply, a tip-speed-ratio of ~6:1 is the distinguishing mark of success. Only good blades will get you there.

We will be pleased to provide a detailed graph comparing a number of well known airfoils, upon request.

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