Like most people, I have not been to 70k feet. But I have a working knowledge of lenses and distortion and have several times spoken out about the distortion in pics posted where it was obvious. I also assumed you had a basic knowledge of distortion since you claimed you saw it. I notice you yet again ignored the proof that you were wrong and chose to insult instead. Cute.
And I see you ignored my question, so I suppose that makes us even.
I just want to know if you really think that is what the curvature would look like at 70K feet assuming the accepted round earth radius/diameter.
I actually had never really considered it until today. But given the geometry its sounds and looks reasonable and seems to look like other u2 shots where the distortion is not obvious. The published service ceiling of a U2 is 70k feet and the horizon at 70k feet would be 324 miles away*.
The first figure is a circle with a radius of 3959. The second is zoomed in on a section with a verticle line of 13.26 (70000/5280). The Horizon is 26.67 miles below the line of sight (4.7 degrees) and the pink area shows how much curvature would be seen in a 325-mile field of view. Looks close enough to the pic for government work.
So yes, it looks close enough for the math.
* Note the horizon is actaully drawn 325.1 miles due to laziness.