Operational Parameter Study of Aircraft Dynamics on the Ground

Abstract

The dynamics of passenger aircraft on the ground are influenced by the nonlinear characteristics of several components, including geometric nonlinearities, the aerodynamics and interactions at the tyre-ground interface. We present a fully parametrised mathematical model of a typical passenger aircraft that includes all relevant nonlinear effects. The full equations of motion are derived from first principles in terms of forces and moments acting on a rigid airframe, and they include implementations of the local models of individual components. The overall model has been developed from and validated against an existing industry-tested SimMechanics model.The key advantage of the mathematical model is that it allows for comprehensive studies of solutions and their stability with methods from dynamical systems theory, in particular, the powerful tool of numerical continuation. As a concrete example, we present a bifurcation study of how fixed-radius turning solutions depend on the aircraft's steering angle and centre of gravity position. These results are represented in a compact form as surfaces of solutions, on which we identify regions of stable turning and regions of laterally unstable solutions. The boundaries between these regions are computed directly and they allow us to determine ranges of parameter values for safe operation. The robustness of these results under the variation of additional parameters, specifically, the engine thrust and aircraft mass, are investigated. Qualitative changes in the structure of the solutions are identified and explained in detail. Overall our results give a complete description of the possible turning dynamics of the aircraft in dependence on four parameters of operational relevance.

Continuation Analysis of Aircraft Ground Loads During High-Speed Turns

“…The analysis is conducted in accordance with the regulations at the maximum ramp weight (MRW) condition, with fore and aft CG positions. The stability results in Section 5.1 for the A320 compare well with the results from previous studies [1,4,5]. A clear boundary is formed by Hopf bifurcations, indicating a loss of grip at the inner main gear tyres [1,4].…”

“…In this study we use validated models of the A320 and the A380 [1,[3][4][5]. The A320 has three landing gears: one nose gear, and two main gears that are attached to the wings.…”

“…The high cost associated with simulations makes continuation techniques attractive, due to the speed with which a global picture of the dynamics can be constructed. Previous studies of the A320 showed how bifurcation methods can be used to detect stability margins, showing how specific bifurcations can be attributed to the loss of grip at specific tyres on the aircraft [1,4,5].…”

Efficient Driving Plan and Validation of Aircraft NLG Emergency Extension System via Mixture of Reliability Models and Test Bench

“…However, landing gear retraction is a sophisticated system, which further comprises many sub-systems like the mechanical, hydraulic, and control devices [9][10][11]. Hence, it is difficult to simulate the real conditions of emergency extension in engineering.…”

Optimization of a Main Landing Gear Locking Mechanism Using Bifurcation Analysis

“…Similarly, the characterization of aircraft ground handling behaviors has been studied using bifurcation analysis method. Bifurcation diagrams in terms of the aircraft velocity and the steering angle were obtained by conducting two-parameter continuations of saddle-node and Hopf bifurcations [17][18][19].…”