E11 Specified as Radius of Dish in 1952 U-1

[dig1]

Hello,

I'm looking at a U-1 Data Report from 1952 and the radius of the dished head is specified as E11.

The vessel is 106" I.D. and the heads appear to be elliptical. I'm not familiar with the E11 designation; does anyone have info on this.

Thanks,

Patrick