Flat earth. Globe earth. A simple proof to find out. At the ocean shore pick a stable subject. Either a boardwalk post, a gas station, whatever, a subject that is small, but a subject that is stationary and doesn't move. Take a helicopter and fly at sea level directly away from the subject towards the ocean, 90 degrees away from the shore. Fly until you no longer see the subject. Stop forward motion. Turn around 180 degrees. Now fly straight up until you see the whole subject, including the bottom of the subject. Stop upward motion. Now fly down to sea level. Flying at sea level, start forward motion. The top of the subject will appear first. As you progress towards the subject you will eventually see the bottom of the subject.
The proof is the ocean is curved, the earth is not flat, it is a globe.
Simple proof.
This simple proof of yours is one of the biggest misconceptions of the globe earth "evidence". This is one reason that I question, not that the earth is a globe, but that they have the size all wrong.
In your test, above, you say to turn 180 degrees and fly straight up until you see the entire object again.
What if you don't have to fly up to see it? What if it is still there even if the calculated curve of the earth should be greater than the height of the object, yet you can still see it?
We have gone over this before. The curve of the earth is, for all intents and purposes of our argument, 8 inches of curve for one mile of distance from the observer.
So, the first mile is an 8 inch drop. The second, however, due to the spherical shape of the surface of, say, the ocean, is 32 inches. The formula for the curve is the number of miles, squared, multiplied 8 inches. Charts for this are posted all over the internet and all agree.
So, at 50 miles the curve would place an object 1600 feet below the visible line of site. 30 miles would be obscured by 600 feet. 100 miles would put an object 6600 feet below the horizon.
However, there are observable structures, recorded in many places, observed without refute and over many years and accepted as truth, that are absolutely proven to be visible on any clear day, on numerous occasions by many people and accepted as being visible..........Yet they should be impossible to see due to the curve of the earth.
There are also examples where a person on shore has observed a ship or boat heading away from them on a large body of water and being observed to disappear over the horizon. However, with a telescope or camera with a telescopic lens, the object can still be viewed in perfect, un distorted detail.
Like I said, this phenomena, being impossible with the earth as it is being presented by science and believed by all sane people, proves that:
The earth is either, not a globe, sphere or does not have any curve at all..... or.... the curve of this globe earth is much less than what they are saying.
In short, the earth is either flat, or a much much bigger globe.
You cannot deny it. Unless you state that the light bends around the curve, which would mean the sun's light should be visible long after sunset as it's light would also bend around the curve and be just as visible as a far off light house that should be concealed by the curve.
They have also done laser tests to prove that, over large distances the surface of the ocean or any body of water is not curved. Unless the lasar bends with it.