Investigation of Energy-Maneuverability Methods for Helicopter Performance Assessments

Energy-maneuverability diagrams are an important tool that operational pilots use to understand helicopter maneuver performance through excess available power across a wide range of conditions. These representations are based upon a number of assumptions that have not been rigorously investigated for helicopter applications. The present work reports the results of an investigation into the theory and application of helicopter maneuverability through simulation and flight test. The computational portion of the work focused on a systematic investigation into some of the key simplifying assumptions that are commonly applied in the creation of energy-maneuverability diagrams using two rotor wake aerodynamic modeling methods. The flight test portion of the work provided important operational context for understanding the practical application of the simulation results. The study illustrated that the fundamental assumption employed in estimating maneuver power requirements for energy-maneuverability representations appears to be reasonable in conditions of the greatest practical relevance; however, another key assumption that is invoked to convert excess power into climb performance would likely lead to overestimating the vehicle capability in important operational conditions. Additionally, the flight test data demonstrated that, at high angles of bank, energy-maneuverability results should be considered for trending information rather than for detailed climb performance values.