Why can you see Chicago from Michigan 60 miles away, not possible on a globe. And no it wasn't a superior mirage, looming, a refracted image or any other nonsensical illusion. You can also see the Superdome from 17 miles away across lake Pontchartrain, not possible on a globe. There are tons of examples of being able to see things that should be beyond the 'horizon'. The formula for the curvature of the earth is 8 inches per mile X mile (mile squared), do the math it doesn't work.
You really haven't thought this thru very well have you?
Please rewrite your "formula" factoring for mean distance ASL between Chicago, IL and Van Buren County, Mi. (right across the lake).