Prediction of Icing Effects on the Lateral/Directional Stability and Control of Light Airplanes

The accumulation of ice on an airplane in flight is one of the leading contributing factors to general aviation accidents, and to date only relatively sophisticated methods based on detailed empirical data and flight data exist for its analysis. This paper develops a methodology and simulation tool for a preliminary yet accurate evaluation of airplane dynamical response and stability and control characteristics due to icing. It uses only basic mass properties, configuration, and propulsion data, together with known icing data obtained for similar configurations. Existing icing data for a light airplane is suitably modified and applied to a non real-time, six degree-of-freedom simulation model of a different but similar light airplane, developed from empirical data and Data Compendium methods. The component build-up method is used to implement icing effects on the wing alone, horizontal tail alone, and various unequal distributions of combined wing and horizontal tail icing as well as ice accretion on only one half of the wing. Results presented in the paper are limited to the roll axis and yaw axis maneuvers with various levels and distributions of ice accretion show that the methodology captures the basic detrimental effects of ice accretion on roll and yaw response and lateral stability, in addition to the sensitivity of pilot control response. Nomenclature A = Plant matrix B = Control distribution matrix C = Output matrix ( ) A C = Arbitrary stability and control derivative ( )iced A C = Arbitrary stability and control derivative with icing effects CD = Airplane drag coefficient CL = Airplane lift coefficient Cl = Airplane rolling moment coefficient Cm = Airplane pitching moment coefficient Cn = Airplane yawing moment coefficient CY = Airplane sideforce coefficient CZ = Stability Z-axis coefficient c = Mean geometric chord Graduate Research Assistant, Flight Simulation Laboratory, Aerospace Engineering Department. Student Member AIAA. [email protected] Associate Professor and Director, Flight Simulation Laboratory, Aerospace Engineering Department. Associate Fellow AIAA. [email protected]. AIAA Atmospheric Flight Mechanics Conference and Exhibit 21 24 August 2006, Keystone, Colorado AIAA 2006-6834 Copyright © 2006 by Amanda Lampton and John Valasek. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. American Institute of Aeronautics and Astronautics 2 D = Carry through matrix d = Distance along body X-axis fice = Icing factor g = Gravitational acceleration h = Integration step size Ixx = Airplane moment of inertia about X-axis Ixz = Airplane moment of inertia about XZ-plane Izz = Airplane moment of inertia about Z-axis i = Index, imaginary component j = Imaginary component kts = knots ' A C k = Coefficient icing factor constant L = Roll angular acceleration LTI = Linear time invariant LWC = Liquid Water Content M = Pitch angular acceleration; modal matrix MVD = Median Volumetric Diameter N = Yaw angular acceleration nframes = Number of time steps P = Aircraft body-axis roll rate p = Perturbed aircraft body-axis roll rate pla = Powel lever angle q = Dynamic pressure R = Aircraft body-axis yaw rate r = Perturbed aircraft body-axis yaw rate rad = Radian S = Wing area sec = Second t = Time U = Control input vector V = Aircraft velocity in the body-axis y-direction W = Aircraft velocity in the body-axis z-direction w = Incremental change in the stability axis aircraft velocity in the z-direction X = Linear acceleration in the body x-axis direction X = State vector X = Derivative of state vector Y = Linear acceleration in the body y-axis direction Y = Output vector Z = Linear acceleration in the body z-axis direction Greek α = Angle-of-attack α = Incremental change in angle-of-attack β = Sideslip angle β = Incremental change in sideslip angle Γ = Discrete control distribution matrix δ = Control deflection angle ζ = Damping ratio