The VIRYA-2.22 with a 2-bladed rotor with stainless steel blades is replaced by the VIRYA-2.7 with a 3-bladed rotor with wooden blades. So the design report of the VIRYA-2.22, KD 676 is cancelled and replaced by the design report of the VIRYA-2.7, KD 717. The reasons are that stainless steel blades require special tools for cambering and twisting and that a rotor with stainless steel blades is probably too noisy because the sharp leading edge causes a turbulent boundary layer. The folder in which the VIRYA-2.7 is described, is also modified.

The two new chapters 7 and 8 have been added to KD 717 at 6-5-2021. The title of chapter 7 is: “Checking if the generator can be used as a brake”. It seems possible to use the generator as a brake to stop the rotor by making short-circuit in star. The title of chapter 8 is: “Use of the VIRYA-2.7 for 12 V battery charging”. 12 V battery charging is possible and the cut-in wind speed becomes only 2 m/s but the maximum power is only 300 W.