Since the PiGI is ultimately cheap to produce once you reach the 1000 pieces boundary it would be great to put this out to the Pi-Community as a ready-to-go module, the only thing that would need soldering is the tube itself (no SMT solderig). If you're interested in having one, please vote for it below:

<math>F_{pole} = \frac{1}{2} \times \rho \times C_d \times A_{wind} \times v_{wind}^2</math>

<x>F_{pole} = \frac{1}{2} \times \rho \times C_d \times A_{wind} \times v_{wind}^2</x>

<x>\rho</x> = Density of air = about 1.2 Kg/m³ <br /> <note warning>C_d = Coefficient of drag = 1.0 (cylinder Re > 100) <br /></note> <math2>A_{wind}</math> = Area of turbine = 4 m² <br /> <note tip><math2>v_{wind}</math> = Wind speed in m/s</note>

h_1=0.32 m d_1=0.32 m A_1=0.1024 m^2 h_2=0.48 m d_2=0.32 m A_2=0.1536 m^2

Assuming a bad (20%) or decent (30%) turbine design \rho_{turbine}=0.26 A rather bad permanent magnet alternator with \rho_{alternator}=0.75; A normal synchronous rectifier with superb-by-design perfomance of \rho_{rect}=0.98; A buck-boost inverter with a good performance of \rho_{rect}=0.85; ⇒ \rho_{overall}=0.25*0.75*0.98*0.85=0.16

<references />

<math> \Rho_{simple drag turbine} = 20% \Rho_{decent} = 30% \Rho_{good} = 30% \Rho_{superb vawt} = 40% </math>