The use of surface pitot tubes as skin-friction meters at supersonic speeds

Abstract

Experiments have been made, in supersonic turbulent boundary layers, on a simple type of surface pitot tube, formed by cementing a piece of razor blade over a static-pressure hole. This type of surface pitot tube has great practical advantages, as surface-shear measurements may be made on any model designed for pressure measurements. A calibration curve, which is sensibly independent of Mach number, has been obtained for the dependence of the pressure rise at the pitot tube on the surface shear, both terms being made non-dimensional. Examples are included of the use of surface pitot tubes on two models. The models were a delta wing and a biconvex cone and the tests covered a range of Mach numbers, Reynolds numbers and model incidence.