Various flow visualization results at a nominal Mach number of 5 are presented for cylindrically blunted, unswept and 60-degree swept fins with and without small clearance gaps, partially immersed in a turbulent boundary layer of about 2.6 inches thickness. In addition, pressure and heat transfer measurements were obtained on the flat plate upon which the fin was mounted. Oil smear, azobenzene and Schlieren flow visualization tests were made.