Sphere drag coefficient for subsonic speeds in continuum and free-molecule flows

An extensive series of measurements of sphere drag coefficients has been made in an aeroballistic range for a broad range of Reynolds and Mach numbers. These measurements have been compared with those obtained in other test facilities. As a result of this comparison it has been possible to suggest reasons for many of the inconsistencies in the earlier measurements and to establish more accurate values of the sphere drag coefficient for M∞ [lsim ] 0·2 and 10−2 [lsim ] Re∞ [lsim ] 107.