Am 18.01.10 22:00, schrieb Jim Logajan:

The abovementioned Helmut Reichmann's "cross country soaring" would be
a perfect starter.

I may buy a copy.

I strongly suggest it.

In the mean time, how does he define the term?

Ad hoc translation from the German book: "Speed to fly (in German
"Sollfahrt") is the speed that fits best your intention. Depending on
your situation it will be different." He then explains it over the next
30 pages.