New Methodologies for Aircraft Stability Derivatives Determination from Its Geometrical Data

Abstract

The common practice for aircraft design and certifi cation is usually based on its flight test data. The aircraft stability derivatives are t he main unknowns to be determined from its flight dynamics model. These aircraft stability der ivatives data are the intrinsic parameters used in the aircraft design - and are dependent on its geometry and on its flight conditions. There is the need of determination with the highest precision of aircraft stability derivatives for all regimes in order to determine the best airc raft flight model possible by use of simulation tools rather than expensive flight test data. A way of obtaining the dynamic and static stability derivatives is using a semi-empiri cal method DATCOM presented in USAF Stability and Control DATCOM reference. A new code called FDerivatives was conceived by us where new algorithms and methods were added, with respect to the DATCOM classical FORTRAN code, to improve the stability derivatives calculations for an aircraft in the subsonic regime. This new FDerivatives code was written under MATLAB 7.4.0 (R2007a) version and has a complex structure which contains a graphical interface to facilitate the potential users work. The new code and interface would allow aircraft designers to evaluate aircraft new design concepts, predict its performan ces, and therefore bring the necessary changes to its design. This code would provide impo rtant savings in man-hours and other resources needed for flight tests. Results obtained in terms of stability derivatives values with the new FDerivatives code are here presented a nd validated with the flight test data results for the Hawker 800 XP aircraft by use of it s aircraft geometry knowledge.