Mass Moment of Inertia

[sinu21]

Dear friends

I am trying to find a mass moment of inertia of an wind turbine on its rotor.
No of blades = 3
Weight of blade = 11.5T
COG = 15m

If i use mass x radius 2
i get 2587.5 x 3 = 7762.5 Tm2

i want to find an equivalent box section with provides me same mass moment of inertia in the same vertical axis.

for a box section = (M/12) x (b2 + h2)


If i keep the mass constant 11.5*3= 34.5 T
b=51m and h=14.5m


can anyone advice me how to best represent a 3 blade rotor to a rectangular box.

Thanks in advance.

Regards