Curvature of 2:1 SE head

[kyong]

Has the 2:1 SE head really elliptical curvature? I mean that do the manufactures make heads with gradually increasing curvature from edge to center or do they use only two curvatures, i.e 0.9d in central area and 0.137d in outer area.
If they use gradually changing curvature, the axis ratios in outer surface and in inner surface are different. Then I can raise a question that which surface 2:1 ratio is representing.

Can anyone give me explanation about this point?

 

[MJCronin]

kyong

See this site:

http://www.bakertankhead.com/products.htm

Typical tank/vessel heads are described here

MJC