Flight Test Planning and Data Extraction

Author: Stefan Velikov



A dynamically scaled model of a business jet design, the Raven, has been built at the Linköping University to investigate the possibilities of flight testing with subscale radio controlled aircraft models within a low-budget university project. This work comprises a theoretical approach of flight test planning and post-flight data handling to identify the aircraftís aerodynamic performance and dynamic behaviour. Calibration methods for pressure sensors are also presented with an emphasis on in-flight test procedures to determine position error and their corresponding data reduction. For drag predictions a basic thrust model of Ravenís engines is included, which consists of linear scaling of available thrust data. Its accuracy is however questionable and is to be further verified. Since determination of aerodynamic performance has high priority during the first tests, main part of this work deals with flight test procedures to determine lift and drag coefficients as a function of angle of attack from a steady level flight and series of steady glides. The corresponding data reduction sequences are adjusted in accordance with the available instrumentation of the Raven. In addition, techniques to investigate aircraft longitudinal and lateral-directional static stability from flight testing are presented with data reduction methods to identify important parameters like neutral point position, pitching moment coefficient and side-force stability derivatives. Furthermore, flight test methods to determine characteristic dynamic stability parameters like damping ratio and frequency for the individual modes of motion are given. This includes various piloting techniques and post-flight results evaluation.