I've actually thought about these 3 questions before and the 1st 2 questions are actually answered by the 3rd question and the 3rd question is all a matter of angles. Firstly your line of sight is always 135 degrees in front of you in respect to your feet and your line of sight is always 135 degrees above you. This means if for example you are inside of a very large ball you will not be able to see the other side above you as your line of sight doesn't reach that far so from your perspective you only see black perhaps tinted with green and red to make blue, yellow, purple or red skylines depending on the light to darkness ratios.
Your line of sight is basically like a football with the upper half always being sky and the lower half always being ground. This happens as light curves up in still reflects towards you up to eye level and then as it passes eye level it actually curves away from you so are not able to see it anymore. Good telescopes can actually alter the starting point of optical curvature so the telescope actually gathers light into it's optics that is closer to the sky (aka higher then you are physically standing basically altering your eye level so that it's like starting at higher elevation) so to see further then the horizon with a good telescope you have to point it slightly above the horizon line.
I will go one step further then this and claim that firstly it is possible to launch and orbit satellites inside the Earth as well as hang them motionless in-between the Earth and Sky neutral zone (like the surface of water). However our measured distances of 20-30 thousand miles is jacked up because we assume the Earth to be a globe and thus all measurements derived from that are messed up.
Also the 8 inch drop per mile comes from the Earth curving up and if you stay locked on the horizon this is what drop you will get. However this is only if you are actually moving at ground altitude. The curvature becomes much less the higher altitudes you gain so if you are for example flying 1 mile high this will only be 2 inches per mile instead of 8. Since most planes fly 5-8 miles the calculation goes as follows.
1 mile high = 2 inches per mile of drop
2 miles high = .5 inches per mile of drop
3 miles high = .125 inches per mile of drop
4 miles high = 0.03125 inches per mile of drop
5 miles high = 0.0078125
6 miles high = 0.001953125
7 miles high = 0.00048828125
8 miles high = 0.0001220703125
and it keeps going quartering itself per mile of altitude gained. So if your flying very high at like 19 miles the curvature would only be like 0.0000000000291038304567337 inches per mile of curvature. However the Earth does look curved when viewed with wide angle optics but then again everything has a fish-eye effect when you try and fit more then 90 degrees field of vision into a computer monitor unless you have one that wraps around your head: " class="bbc_link" target="_blank" rel="noopener noreferrer">
After reading, re-reading and thinking about this and some of your other posts for the better part of a day, I'm still not sure at all that I understand what you're saying. Here's a stab:
We're inside a sphere about 4,000 miles radius. "The heavens" are contained in a smaller sphere that is centered on the same center as ours. For whatever reason, light from the surface only reaches our eyes from a maximum angle of 45 degrees above our local horizontal (135 degrees from straight "down"). Above that is blackness (or perhaps featureless color). Is this right? I just don't see how this is plausible. If I'm in a cave, say, and look up I see the cave roof. If i"m outside on a partly cloudy day I can see clouds move from horizon to overhead.
If we're living inside a hollow earth and I'm standing at 90 degrees W longitude, how come I don't see the Atlantic Ocean, western Africa, and parts of Europe rising up in the east before disappearing above the 45-degree upward limit?
How do sunrises and sunsets work? How can a star like Vega appear to rise in the northeast, pass directly overhead, and set in the northwest? Or, say, Antares, rise in the SE, culminate not quite 45 degrees up in the south and set in the SW?
In the table of curvatures, why is the statute mile so significant? Since the relationship appears to be
drop per mile = 8" / 2^(twice the height in miles)
(the ^ symbol means "raised to the power of") the unit "mile" has particular significance. Did this just happen to coincide with a common measure of length in the USA (and almost nowhere else), or does the statute mile have some mystical significance? Even if this is right, what does it mean? Two planes flying parallel straight paths with one mile difference in altitude will change altitude at different rates?
After trying to understand this, I'm still totally baffled. Isn't being on the outside of a sphere of about 4,000 miles radius a lot easier to explain? I just don't see any plausible reason to think we're inside a hollow earth.