Unique Calibration of a "5-hole" Pitot Rake and Application for Wake Survey

A rake of five “5-hole" directional Pitot tubes (actually "6-hole" because static taps are included) was calibrated for angular sensitivity, as well as velocity, in a towing tank. This was; accomplished by deploying the rake on a tubular shaft out of the bow of a propeller boat. Combinations of propeller boat yaw angle and rotation angle of the rake shaft provided a full and systematic coverage of flow angles in tangential and radial planes of each probe. Thirty single ended pressure transducers were used, one for each hole in each of five probes, to measure pressures. The transducers resided below the waterline, making air purging practical. Calibration required forty one runs.