The Integration of a GPS Receiver to a Quasi-Real Time Decision Aid Tool Used for the Air Data System Calibration Flight Tests Campaign

N.P. Oliveira-Leite, L.M. de Faria Lopes, F. Walter

Abstract:	The first flight test campaign carried out for an experimental aircraft is the calibration of its air data system. In this case, the aircraft measured altitude and speed, provided by both anemometric and the Flight Tests Instrumentation (FTI) systems are corrupted by installation errors. Therefore, the determination of such errors will also correct the measurements of a production aircraft. To accomplish that the aircraft measurements are compared to the equivalent reference measurements. Usually the references are provided by multiple sensors, including: a ground based wind reference; an optical tracking; and a differential GPS. The most usual process used at this campaign is the tower fly-by method which the altitude indicated by the aircraft pitot-static system is compared to the actual pressure altitude to determine the static pressure error. The Brazilian Flight Tests Division (GEEV) holds the Flight Tests School (CEV) for both rotary and fixed wings. The syllabus of this school includes the execution of such flight tests campaign. The students fly aircrafts fully instrumented, where all required airborne data are acquired, stored and transmitted. During the test flights FTI data is received at the Ground Telemetry System (GTS) and merged with complementary measurements that arise from other sensors (i.e. Ground based wind reference system). Normally, the GTS is a monitoring station, so all data reductions require long processing time, and they are performed in post mission operations. To improve the efficiency the GEEV development group (GEEV CP&D) along with EMBRAER has developed a new concept where all required data processing is performed during the flight so the tests results and reports are ready at the end of the last valid test point. Therefore, a decision tool operating in a quasi-real time was developed. The preliminary tests of this tool showed an expressive increased of his efficiency. The next step is to integrate with a differential GPS to improve the model accuracy. To accomplish this a rover GPS receiver is integrated with the FTI, where all GPS observables are merged into the PCM stream, and a reference GPS receiver is integrated with the GTS so, the decision aid tool can perform the GPS differential correction, and use them for the air data system calibration. This paper will discuss such architecture, its preliminary development under MATLAB® environment, and the preliminary tests results. To assist this task the XIX CEV class students performed several flights at both XT-27 (EMBRAER Tucano basic trainer), and XAT-26 (EMBRAER Xavante jet) aircrafts showing promising results.
Published in:	Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009) September 22 - 25, 2009 Savannah International Convention Center Savannah, GA
Pages:	1619 - 1629
Cite this article:	Oliveira-Leite, N.P., Lopes, L.M. de Faria, Walter, F., "The Integration of a GPS Receiver to a Quasi-Real Time Decision Aid Tool Used for the Air Data System Calibration Flight Tests Campaign," Proceedings of the 22nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2009), Savannah, GA, September 2009, pp. 1619-1629.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In