Aircraft flight dynamics with simulated ice accretion

Abstract

The effect of ice accretion on aircraft performance and control during trim conditions was modeled and analyzed. A six degree-of-freedom computational flight dynamics model was used to study the effect of ice accretion on the aircraft dynamics. The effects of turbulence and sensor noise were modeled and filters were developed to remove unwanted noisy data without affecting the short period and phugoid modes. This study is part of a larger research program to develop smart icing system technology. The goal of the study reported here was to develop techniques to sense the effect and location of ice accretion on aircraft performance and control during trimmed flight. Control surface steady and unsteady hinge-moments were modeled as a potential aerodynamic performance sensor. Microburst and gravity wave atmospheric disturbances were modeled and their effects on the aircraft performance and control were compared to that of an icing encounter. The simulations showed that atmospheric disturbances could be differentiated from icing encounters. The hinge-moment sensors proved very useful in identifying the wing versus tail location of aircraft icing. LIST OF SYMBOLS AND ABBREVIATIONS C(A) arbitrary performance or stability and control derivative Q airfoil drag coefficient Ch hinge-moment coefficient CH, RMS unsteady hinge-moment coefficient Ci lift coefficient Cm pitching moment coefficient Fx, Fy, Fz forces on the aircraft FDC Flight Dynamics Code g(n) freezing fraction effect on drag h altitude IMS Ice Management System IPS Icing Protection System kCA coefficient icing factor constant kc coefficient icing factor LWC Liquid Water Content MVD Median Volumetric Diameter m aircraft mass n freezing fraction p, q, r aircraft angular velocities qg effective pitch rate due to gust velocity r radial coordinate R microburst radius SIS Smart Icing System T temperature t time TIP Tailplane Icing Program u, v, w atmospheric velocities V aircraft, freestream velocity x, y, z rectangular coordinates Zi,2,3 drag equation constants z* characteristic height out of the boundary layer A change a angle of attack 5e elevator deflection A microburst constant 77 aircraft icing parameter r/ice icing severity parameter * Graduate Research Assistant, Department of Aeronautical and Astronautical Engineering, currently Aerospace/Simulation Engineer, NLX Corporation, Sterling, VA, Member AIAA. f Professor and Head, Department of Aeronautical and Astronautical Engineering, Associate Fellow AIAA. Graduate Research Assistant, Department of Aeronautical and Astronautical Engineering, currently Aeronautical Engineer, Naval Air Warfare Center Aircraft Division, Patuxent River, MD, Member AIAA. * Graduate Research Assistant, Department of Aeronautical and Astronautical Engineering, Member AIAA. Copyright 2001 © by Michael B. Bragg. Published by American Institute of Aeronautics and Astronautics, Inc. with permission. American Institute of Aeronautics and Astronautics c)2001 American Institute of Aeronautics & Astronautics or Published with Permission of Author(s) and/or Author(s)' Sponsoring Organization.