This publication develops the first correlation equation between the theoretical turbulent skin friction with Preston-tube measurements on a subsonic cone. Lecturers, scientists, and practicing engineers in the field of fluid dynamics should be interested in this development. The goals of this NASA sponsored research are in two fold: (1) to develop a new procedure which could be used to develop a correlation equation for correlating Preston-tube pressure measurements within turbulent boundary layers with the corresponding theoretical values of skin friction coefficient, and (2)...