Weird idea about orbits...

[christo4_99]

  For circular orbits in about a central field source, there is no "inertia loss" at any radius.  The linear momentum vector changes its direction continuously, but it does not change in magnitude.

seems to me that an object continuously changing direction would lose velocity...simply because of its tendency to travel in a straight line and not a curve...nothing travels naturally in a curve unless it is tethered to a center,and if it is tethered some of the energy is lost in the cord so it cannot sustain it's velocity continuously.

[GestaltO]

putting it extremely simply. an orbit is a continual slingshot effect due to initial speed build up from gravity (pulling the slingshot) then as for example the moon is just about to hit it goes around the back of the earth and does the same thing on the other side. depending how far away the object orbiting initially is from the thing that it is orbiting depends on the shape of the orbit.