Aircraft Dutch Roll and State Variables Analysis Using Yaw Damper and Washout Filter

N. Abdulwahab, Emad

doi:10.30684/etj.27.7.11

	Aircraft Dutch Roll and State Variables Analysis Using Yaw Damper and Washout Filter
Engineering and Technology Journal
Article 1, Volume 27, Issue 7, 2009, Pages 1351-1369 PDF (304.21 K)
DOI: 10.30684/etj.27.7.11
Author
Emad N. Abdulwahab
Abstract
Many high performance aircraft suffer from a dynamic instability problem at relatively high Mach number and altitude regimes known as Dutch roll instability. In this study the aircraft Dutch-roll and lateral –directional state variables may be enhanced using the yaw damper and washout filter. The Aircraft Dutch-roll damping is improved by identifying a suitable feedback gain matrix plus preserving the airframe's low-frequency behavior by the use of a washout filter with a time constant. An intermediate change in terminology is used to illustrate the procedure for including a washout filter into the aircraft lateral state equation formulation. A stability augmentation system (SAS) and a numerical model constructed for a Mig-21 aircraft are solved to illustrate the proposed procedure. The numerical results show that it was sufficient to use (SAS) including both yaw damper and washout filter to improve the aircraft sideslip angle, roll rate and roll angle response in a short time. Finally, the verification of the aerodynamic characteristics of present model was made by comparing the results of the method used (Low order three dimensional Panel method) with that of Cy-20 aircraft flight data test.
Keywords
Dutch roll damping; Yaw damper; Washout filter; Stability augmentation system

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