miles of super cable to kite launch vehicles to high mach/ high altitude

[froarty]

Before new carbon based cables ever achieve the strength needed for a space elevator lower strength material like newly discovered "super thread" http://thefutureofthings.com/news/1292/superthread-strongest-carbon-nanotube-ever.html should allow us to use ground based rail gun highways to "tow" scram jets and small lifting bodies along the cable like multiple kites on a string with miles of super cables to "launch" these air breathers to ignition speed and altitude. I know escape velocity is totally out of reach at low altitude but how much heat/speed will these new wonder materials be able to survive at sea level? any thermal experts out there? Now for an even wilder idea... a circular track with tether paid out beyond the atmosphere using centrifugal force to propell a payload to escape velocity -way beyond my math skills to determine optimum track circumference and tether speeds but
my point is the payload at the end of the tether is traveling much faster than the earth bound "tractor" but would the tractor and tether be able to go slow enough to avoid melt down while still travelling fast enough to keep the centrifugal force on the pay load?