Research On Optimization Of Helicopter Flight Following One-Engine Failure

This paper studies optimal helicopter flight operations in the event one-engine failure. A three-dimensional point mass with a yawing motion of UH-60A has been used to study RTO and CTO from an elevated heliport or from a heliport, A first order dynamic of the OEI contingency power is considered.Flight after engine failure are formulated as nonlinear optimal control problems. The performance index is selected in a way that reflects the main parameters to be optimized. Subject to helicopter equations, path constraints, FAA regulations. These optimal control problems are solved numerically using a direct approach. States, controls, and helicopter constant parameters are parameterized, and a collocation method is employed. The problem is then fed to a nonlinear programming routine to solve for all parameters.The flight dynamics model with yawing motion of UH-60A is given, Scale factors of state variables and control variables are applied based on the consideration of algorithm convergence. then, the optimization of trajectories is expressed as optimal control problem with a performance index constrained by helicopter performance limits, FAA regulation and so on. Finally, we convert this optimal problem to a nonlinear parameter optimization problem by collocation method.These studies examine the collocation method in case of equally or non-equally spaced division points, and in case of different numbers of nodes. VTO and STO optimal trajectories are calculated, and we analyze effects of initial velocities, initial height, initial gross weight on the optimal control. Then we use optimal control theory to determine TDP in case of VTO and STO. H-V diagrams are determined using flight tests, they are time-consuming and dangerous. Therefore, the following optimal control problem is formulated to determine the boundary of a H-V diagram in case of OEI.Due to complicated continuous helicopter models and a wide range of constraints, numerical solutions on a mainframe computer have to take a long time. For a given set of initial helicopter states and flight parameters, optimal solutions are fitted by a Fourier series. The coefficients of the Fourier approximations are then interpolated as functions built by three-layer BP network with inputs of initial flight states and parameters. This method can provide optimal trajectories in real time for cockpit display and give pilot a useful reference when occurring OEI.