On Thursday, June 20, 2013 1:53:31 PM UTC-6, Steve Leonard wrote:
http://www.ntsb.gov/aviationquery/br...FA010 &akey=1



Happened to be looking through the NTSB Database and saw that they updated the report about a month ago.

Some have said there's nothing new in this report. Indeed there remain some missing details, but there is also a new fact that I don't recall from the prior reports and my inquiries, including discussion with the observer in the back of the launch vehicle.

If the facts are correct, anyone involved in ground launching should have zeroed in on the rope. Nylon rope is very elastic compared to premium UHMWPE ropes, that is, nylon has some 16% elongation at 15% of breaking strength.. UHMWPE rope elongation at 30% of breaking strength is under 1%.

Working limits of premium UHMWPE and steel wire ropes are 1/5 to 1/6 of breaking strength. During winch launching we tend to operate beyond these working limits regularly by loading to 1/4 to 1/3 of breaking strength with premium UHMWPE ropes, and presumably as high as 3/5 with the regular UHMWPE and steel wire ropes. For all practical purposes, there is minimal elongation.