Report KD 600, which was originally written in 2015 is totally reviewed and now public available. The title of this report is: “Diffusers for wind turbines”. On 5-9-2025 a new alinea about a massive disk has been added to chapter 1 and a new alinea about the law of Bernoulli has been added to chapter 2

Report KD 763 about the VIRYA-7 is reviewed. The Gö 711 airfoil is replaced by the Gö 797 airfoil and only the blade construction with round bars as spokes is used. This resulted in a strong modification of the tekst.

A new chapter 5 has been added to report KD 333. The title of this chapter is: “Geometry of the Gö 797”.

Report KD 732 about the VIRYA-14 is replaced by report KD 783 about the VIRYA-13. The title of KD 783 is: “Calculations executed for the 3-bladed rotor of the VIRYA-13 windmill (lambda design = 6) with the hinged side vane saftey system connected to the generator type PMG900-I-30KW-100R for grid connection”. The hinged side vane safety system of the VIRYA-13 seems simpler to build as the pendulum safety system of the VIRYA-14.

Report KD 774 which describes the VIRYA-10R with a 2-bladed rotor made out of Roofmate and epoxy is replaced by report KD 772 which describes the VIRYA-10S with a 3-bladed rotor made out of stainless steel sheet. A 3-bladed rotor is more beautiful and less sensible to vibrations.