Full scale propeller tests are extremely expensive and limited by the availability of large high speed tunnels. The use of models is an alternative, and considerable experience has been obtained from recent British programmes involving small models, the design and construction of which, including the use of composite materials, are discussed.A series of performance tests carried out on a model in a variable density tunnel at flight Mach. numbers, with measurement errors of less than ± 1.0%, provided some observation of the influence of Reynolds number. The lower speed results, compared with full scale tunnel data, after correction for scale effects, showed very close agreement. Samples of results from another comparative test programme are included showing similar agreement both aerodynamic and acoustic.