Articles | Volume 8, issue 8
Research article
12 Aug 2015
Research article |  | 12 Aug 2015

Calibration of 3-D wind measurements on a single-engine research aircraft

C. Mallaun, A. Giez, and R. Baumann

Abstract. An innovative calibration method for the wind speed measurement using a boom-mounted Rosemount model 858 AJ air velocity probe is introduced. The method is demonstrated for a sensor system installed on a medium-size research aircraft which is used for measurements in the atmospheric boundary layer. The method encounters a series of coordinated flight manoeuvres to directly estimate the aerodynamic influences on the probe and to calculate the measurement uncertainties. The introduction of a differential Global Positioning System (DGPS) combined with a high-accuracy inertial reference system (IRS) has brought major advances to airborne measurement techniques. The exact determination of geometrical height allows the use of the pressure signal as an independent parameter. Furthermore, the exact height information and the stepwise calibration process lead to maximum accuracy. The results show a measurement uncertainty for the aerodynamic influence of the dynamic and static pressures of 0.1 hPa. The applied parametrisation does not require any height dependencies or time shifts. After extensive flight tests a correction for the flow angles (attack and sideslip angles) was found, which is necessary for a successful wind calculation. A new method is demonstrated to correct for the aerodynamic influence on the sideslip angle. For the three-dimensional (3-D) wind vector (with 100 Hz resolution) a novel error propagation scheme is tested, which determines the measurement uncertainties to be 0.3 m s−1 for the horizontal and 0.2 m s−1 for the vertical wind components.

Short summary
We demonstrate a calibration method for the three-dimensional wind measurements on a research aircraft, which are strongly influenced by dynamical effects during flight. We correct these errors step by step after an extensive test flight program including new methods to gain optimum correction coefficients and a direct estimation of the residual errors. The overall error, estimated with a novel error propagation scheme, is 0.3 m/s for the horizontal and 0.2 m/s for the vertical wind.