And I have watched a helicopter (with one of those cameras) disappear below the horizon of a lake. It looked like it landed and then went into the earth. Meanwhile, the people on the helicopter were in contact with the team in charge of the camera. The helicopter was still 30’ off the ground when it disappeared below the horizon. When math was applied, it was a perfect fit to a round earth that is a little less than 8,000 miles in diameter. It’s an experiment anyone with a few hundred bucks and a calculator (and an open mind) can do.
That same team shot a fixed laser at a boat and the laser gained altitude on the side of the boat as the boat gained distance from the shore-moving from 2’ above the water line at the shore to more than 12’ above the boat several miles away. This stuff is pretty simple actually.