In report KD 35 (ref. 1) a method is given for the design of a windmill rotor. The blade of the rotor must be provided with an aerodynamic airfoil. In the examples in chapter 5.4 of KD35 the Gö 623 airfoil is used. This is a good airfoil for small wind turbines and it can be used for wooden blades. It is used in the VIRYA-2.2, -3, -4.2 and -4.6 windmills developed by Kragten Design (KD). However wooden blades are rather difficult to manufacture, need to be painted very well and are sensible for damage during transport. Therefore KD is developing a range of small windmills using galvanised steel or stainless steel sheet for the rotor blades.