An Investigation of Atmospheric Turbulence Probes with Ground Test Comparisons of Probe Head Designs and Evaluation of Suitability to Instrumented Aircraft

A comparison of methods to determine the flow angle components of atmospheric velocity vectors is presented. The atmospheric turbulence probes used to measure behavior of the atmosphere use different methods to obtain this information and there is some confusion as to which method is best. Although the methods are all based upon potential flow theory, the details about how the atmospheric and flight parameters are measured makes a difference to the design of an atmospheric turbulence probe and carrier research aircraft. This paper presents the mathematical theory behind five methods of obtaining atmospheric flow angle measurements from a moving aircraft. One of these methods, the Flush Air Data Sensing system developed by NASA has not previously been used in this particular application before but is found to be just as accurate as more commonly used methods that utilize a hemispherical sensing head. In fact, none of the methods presented show any statistical improvement at measuring flow angles over the others. It is therefore suggested that the best method is one that considers the probe and aircraft as a whole system rather than preferring one method over another.