Quote:
Originally Posted by kach22i
Based on that NASA CD Shapes illustration, I think it/they would say the half-sphere is more aerodynamic than the lower rectangular one. Somehow my intuition says otherwise.
What do you all think? |
I think the half-sphere will have less drag due to skin friction. The rectangular mirror has about 7 times the surface area.
Round: area = 4PiRR/2 = 4(3.14)2(2)/2 = 12.56 sq in.
Rectangular: area (appx) = 5.5(2)8.375 = 92.125 sq in.
92.125/12.56 = 7.33
So unless you use a laminar-flow shape, I think the rectangular will be worse. But the laminars have their own set of problems - surface smoothness and cleanliness are paramount. Hard to maintain on a car.