On Monday, July 11, 2016 at 5:22:38 PM UTC-7, Ramy wrote:
Unless you fly in completely stable air, the post flight analysis L/D has more to do with the soaring conditions and how well you utilize energy lines, than glider performance.

Ramy

While that is true, flights done from a high tow in early morning stable conditions specifically to measure performance, might be usefully analyzed from logged data. Set the logger to 1 second intervals, pilot comment each change of speed, etc.

You would still need to correct the data to standard atmosphere, which I believe DJ did.