Contrary to what some believe the Earth isn't flat. But just how curved is it?
First of all the Earth is a SPHERE:
It's been said that the drop per mile, because of the Earth's curve, is 8 inches. I don't think so!
The Earth's Circumference is roughly 24,900 miles. [24,901.461 at the Equator to be exact.]
Now, 24,900 divided in half is 12,450 miles. That's the distance of the Equatorial distance to the opposite part of the Earth. One half of that is 6,225 miles. This is the distance from a Pole to the Equator.
[The Earth isn't a perfect Sphere but for the purpose here I believe it can be treated as one.]
The Earth's Radius is 3,950 miles. That's from a Pole to the center of the Earth.
If a plane flies from a Pole to the Equator it not only will have gone from a horizontal orientation to a vertical orientation--as seen from Outer Space--but it will have traveled the Earth's Radius of 3,950 miles. In short, it will have traveled 6,225 surface miles AND take position 3,950 miles straight down directly across from the Earth's Center which is 3,950 miles straight down from the plane's original position at the Pole.
Now, relative to the Radius of the Pole to the Center of the Earth the plane has flown downward 3,950 radius miles/6,225 surface miles. This equals 0.63453815261044176706827309236948 miles downward for every surface mile! Or, roughly .63 miles. A far cry from 8 inches!
When pilots think they are in level flight they are actually traveling sharply downward, but not toward the ground. It is the ground that is sloping downward! They are 'level with the Earth', but not from the ground beneath them at start point. Gravity tells them they are flat with the ground and air pressure is affected by gravity.
In short, if a pilot flies level with his start point he will be ascending from the Earth rapidly. If he follows the Earth using barometric or radar altimeter showing he's level he will actually have a downard slope of 0.01445783132530120481927710843373 degree per mile cumulative!
If you fly a fighter jet flat (not with Earth curvature) with your start point at max speed and at a high altitude (80,000+ feet) where air resistence is greatly reduced you can idle the throttle and coast enormous distances with miminal speed loss.
I welcome comments! Any fighter jet pilots out there that have experienced this?