Ballistic Launches

>
> C. How much would this change if the original force was
> applied at say 40,000 feet.

Less that you would think. There have been some proposals for launching
rockets from high-altitude balloons, but the problem with getting into orbit
is chiefly one of achieving the needed velocity. The potential energy
aspect of it is a relatively minor thing.

That said, ballistic launch from high altitude would help to reduce one
serious problem: air drag (and its attendant heating). O'Neill thought that
the ultimate space launcher might be something like a giant mass-driver
suspended in the upper atmosphere by solar-powered hot air balloons. I even
wrote a SF novella about such a thing named "The Bridge to Space":

http://members.aol.com/howiecombs/bridge.htm

But I warn you that I'm not sure how seriously I take even my own
speculations in this area.

Another important point is that one could not achieve orbit on a ballistic
launch alone. One would need an (admittedly modest) rocket engine for an
orbit circularization burn at apogee.

Regards,

Mike Combs