Optimization based inverse simulation method for helicopter pull up maneuver

Abstract

The aim of this work is to perform helicopter Pull Up maneuver with inverse simulation methodology. This method is based on the combination of Broyden-Fletcher-Goldfarb-Shanno (BFGS) and line search optimization algorithms. By using the inverse simulation method, unsteady maneuvers can be performed automatically by changing the control inputs of the helicopter. In addition, maneuverability, agility and performance limits can also be determined. In the conventional methods, trial-error is being performed in order to achieve the maneuver. However, inverse simulation method not only saves time due to trial-error but also increases the accuracy of the aimed maneuver. In the inverse simulation numerical optimization problem, pilot control inputs are defined as the design variables. By changing the pilot inputs, objective function which defines the target maneuver is minimized. The algorithm is used to perform a Pull Up maneuver at maximum achievable load factor for a large category rotorcraft within the available engine power and rotor control limits. Flightlab® software is used for the flight simulations. In mathematical model, blades are modelled as rigid and flow is modelled as uniform inflow. Nonlinear transient Pull Up simulation have been performed and maximum 3.5g is obtained.