Prediction of Icing Effects on the Dynamic Response of Light Airplanes

Abstract

The accumulation of ice on an airplane in flight is one of the leading contributing factors to general aviation accidents. 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 preliminary safety and performance evaluations of airplane dynamic response and climb performance in icing conditions. The important aspect of dynamic response sensitivity to pilot control input with the autopilot disengaged is also highlighted. Using only basic mass properties, configuration, propulsion data, and known icing data from a similar configuration, icing effects are applied to the dynamics of a non-real-time, six degree-of-freedom simulation model of a different, but similar, light airplane. Besides evaluating various levels of icing severity, the paper addresses distributed icing which consists of wing alone, horizontal tail alone, and unequal distributions of combined wing and horizontal tail icing. Results presented in the paper for a series of simulated climb maneuvers with various levels and distributions of ice accretion show that the methodology captures the basic effects of ice accretion on pitch response and climb performance, and the sensitivity of the dynamic response to pilot control inputs. Nomenclature= arbitrary stability and control derivative C A iced = arbitrary stability and control derivative with icing effectshe has been with Texas A&M University, where he is Associate Professor of aerospace engineering, and Director of the Flight Simulation Laboratory. He teaches courses on digital control, nonlinear systems, flight mechanics, aircraft design, and coteaches a short course on digital flight control for the University of Kansas Division of Continuing Education. Current research interests include control of morphing air and space vehicles, multi-agent systems, intelligent autonomous control, vision-based navigation systems, and fault-tolerant adaptive control. He is an Associate Fellow of AIAA, past Chairman and current member of the Atmospheric Flight c = mean geometric chord D = carry through matrix f ice = icing factor g = gravitational acceleration h = integration step size I yy = airplane moment of inertia about y axis i = index, imaginary component j = imaginary component k 0 C A = coefficient icing factor constant L = roll angular acceleration M = pitch angular acceleration; modal matrix N = yaw angular acceleration nframes = number of time steps P = airplane body-axis roll rate p = perturbed airplane body-axis roll rate Q = airplane body-axis pitch rate q = perturbed airplane body-axis pitch rate _ q = airplane body-axis pitch acceleration q = dynamic pressure R = airplane body-axis yaw rate r = perturbed airplane body-axis yaw rate S = wing area t = time U = airplane velocity in the body-axis x direction U = control input vector u = stability axis airplane velocity in the x direction _ u = incremental change in the stability axis airplane velocity in the x direction V = airplane...

Adaptive Control of Aircraft in Uncertain Icing Conditions

“…This method allows for changes in the aircraft aerodynamics due to ice accretion to be represented mathematically. This research, as it pertains to aircraft dynamics, was extended in [4], [3], and [5]. The body of work mentioned in the previous references form the basis for the effort presented in this thesis.…”

“…Worse still, the de-icing systems could cease to operate at all. The type of ice and the severity of which it accumulates is highly dependent on the velocity of the airplane, exposure time, atmospheric air temperature, liquid water content, and the median volumetric diameter of the liquid drops [3].…”

“…The work presented in [4], [3], and [5] details a method to model airplanes with ice accretion for which no ice accretion data either exists or is available for use. It accounts for changes in dynamic response due to unequally distributed icing levels and severity between the wing, the horizontal tail, and the full aircraft.…”

“…It accounts for changes in dynamic response due to unequally distributed icing levels and severity between the wing, the horizontal tail, and the full aircraft. In this model it is assumed that differing levels of ice on the wing and tail appear as changes in the lift and drag force of a lifting surface which in turn leads to a decrease in stability and control [3].…”

“…A slightly different approach to modeling ice accretion on aircraft, compared to the method presented in [4], [3], and [5], is presented in [54]. From data obtained in wind tunnel tests, the force and moment coefficients were broken down into components.…”