Having established the input power required to turn the alternator the blades needed to be designed to provide the power. The wind power calculator
was used to match the alternator power curve with values.
This gives the power curve below.
The alternator will start charging at around 300 rpm which equates to a wind speed of about 3m/s.
The blades were made using an early version of the pipe blade designer
with the following values.
The coefficient of performance and coefficient of lift values are estimates. The blades were made from semi circular PVC gutter described in the pipe blade design
The chord at the tip and root of the blades came out very close to the original Mk1 version. The mounting holes, however, were noticeably further in from the trailing edge, setting the blades at a shallower angle and allowing the turbine to rotate faster.