If an airplane literally just kept flying straight ahead, it would soon miss the curve of the earth and disappear somewhere in the universe. How is that prevented?
Answer
An airplane “surfs” on the atmosphere (the sky) with its wings. In addition, it measures the height at which it flies and relative to the ground. Since the atmosphere follows the curvature of the earth (due to the gravitational force that is about the same everywhere around it), it will therefore (if flying at a constant altitude) follow the curve of the earth nicely.
If it were to fly “straight ahead” as you say, it would climb higher and higher, where the air would become thinner, and at a certain point the lift of the wings would decrease to such an extent that the plane could no longer rise, and so again the round would follow.
Answered by
Prof.dr.ir. Hendrik Van Landeghem
Industrial Management Operations Research
http://www.ugent.be
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