Myth: 1 G barrel rolls are impossible.

Well, MX, consider the case of a ballistic track that starts off with
an initial vertical velocity that is less than escape velocity.

Up, then down, until it hits what someone so nicely described as 'the
hard edge of the sky". Is your assertion that is orbital?

Suppose that, as the rock was passing through the soft part of the sky
(we neglect air friction because this is powered freefall flight), the
earth shrunk to the size of a walnut. The flight path would stay the
same, and orbit the walnut.

Escape velocity is the velocity required to escape the earth's
gravitational field (go up and not come down at all). What we call
"orbital velocity" is the velocity required to remain in a circular
orbit around the earth, at an altitude of about four thousand miles
above the earth's center. At the apogee of a sufficiently elliptical
orbit, the actual velocity can be arbitrarily small.

Jose
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