The Design of Dynamic Calibration Procedure

Abstract

The execution of experimental Flight Test Campaign (FTC) provides all information required for the aircraft operation and certification. Nowadays all information gathered during a FTC is provided by the Flight Test Instrumentation System (FTI) that is basically a measurement system. Typically for all FTI parameters, the estimation of the calibration coefficients that minimizes most of systematic errors and its associated uncertainty is carried out by a Static Calibration Process. To execute this task the Brazilian Institute of Research and Flight Test (Instituto de Pesquisa e Ensaios em Voo - IPEV) developed the Sistema de Automação do Laboratório de Ensaios em Voo (SALEV©) which is fully compliant with the calibration and uncertainty expression standards. For some parameters (i.e. Static Pressure) the sensor installation particularities (i.e. Pressure tapping) introduces low pass filtering characteristics into the measurement chain. In this case the measurement accuracy will be jeopardized when executing high-dynamic test points (i.e. Spin Tests). To overcome this issue the IPEV research and development group introduced a dynamic calibration process for flight test parameters that requires the knowledge of the actual Transfer Function (TF). The problem now is to simulate an impulsive input for the TF characterization which is too complex. To solve this issue a new calibration procedure was developed and evaluated for the determination of the FTI dynamic response. SALEV© was used to simulate a step input instead of an impulse. Then filtered and unfiltered data was properly compared for the determination of the TF. Preliminary test results show satisfactory performance.