Are Lynch's Horizon Calculations correct?

[Laser]

In a thread about calculating altitude from earth curvature pictures, a post on the ARocket mailing list says "The method for determining altitude from earth limb imagery is detailed in the 75th anniversary issue of the RRS News currently available for a $10 donation at rrs.org." I haven't seen it, but it could be useful info for someone wanting to calculate curvature.

 

[Laser]

I've stumbled on a horizon curvature calculation in Italian. Google translate seems to do a pretty good job, except my browser isn't rendering the math markup. Also I don't seem to be able to leave a comment, so maybe someone here should contact him and let him know about this thread.
https://flatearthdelusion.blogspot.com/p/curvatura-orizzonte-geogebra.html