a disk with interchangeable faces of compliant membrane/substrate combinations was spin-tested in a water tank. a device for stretching a membrane uniformly and with repeatable results was designed, fabricated, and successfully employed. six membrane materials and three substrate materials were utilized to fabricate over 36 different compliant disks. each of these was tested in turbulent flow over a reynolds number range of 1.77-2.95 x 10 to the 6th power. a maximum drag reduction of 19 is indicated from tests with a heavy polyurethane membrane unbonded to an organic rubber substrate. this amount of drag reduction is inferred from data taken with polyurethane sheet material which had a rough surface finish. thus, additional tests with smooth polyurethane membranes are needed to verify the reported drag reductions. the present results tend to follow ash's membrane frequency criterion; other data for similar membranes suggest this criterion may be a necessary but not sufficient condition. it is recommended that future exploratory studies of the hydrodynamic drag reduction potential of membrane walls be done with flat plates in order to facilitate more detailed flow measurements