Rosenberg and Bridzell (1986, p. 150) briefly mention that it took John Harrison four long tries before he got the chronometer right.
This is the case wonderfully documented in:
Sobel, Dava. Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time. 1st ed. New York: Walker & Company, 1995.
Another example of dogged persistence is Cyrus Field, as described in the A Thread across the Ocean.
Yet another is Marconi, as described in Thunderstruck.
These are good examples of the type of entrepreneur I tentatively call the ‘project entrepreneur’. (As contrasted with entrepreneurs who have other primary motives, like making money, or winning for the sake of winning.)
I’m going to keep looking for the best name for this type of entrepreneur; maybe the ‘idealist entrepreneur’?