The Design of Static and Pitot Static Tubes Jor Subsonic Speeds

Abstract

The design of the static and pitot static tubes which are still in common use—such as the National Physical Laboratory standard head or the Prandtl tube, dates back some forty years (see Ref. 1). Before these tubes can be used it is necessary to calibrate them, using a replica of the instrument which is commonly regarded as the standard. This procedure assumes a perfect replica. Furthermore, the shape of the instrument head used hitherto (conical or hemispherical) is known to be aerodynamically poor and, as a consequence, the calibration factor varies unpredictably with wind speed, stream turbulence and Mach number.