I have a few aircraft ( X-15, XB-70, Space shuttle) that I would like to test above 100,000 feet. When I get to 100,000, the plane just hangs there. Any way to edit this behavior?
Unfortunately not. 100,000ft is the absolute limit of the fs2k2 "universe". Your aircraft will not go higher than this and as The FS world is a cylinder and not a sphere you will see no curveture in any case.