Conceptual design of a distributed electric anti-torque system for enhanced helicopter safety and performance

Abstract The flexibility offered by distributed electric propulsion (DEP) has triggered in the recent years a variety of new aircraft concepts, showing a way to improve the overall efficiency, capabilities and robustness of the future air vehicles. In com- parison, the conventional helicopter tail rotor, with its vulnerable and complex installation, looks like an example of system application ready to take advantage of DEP, both in terms of redundancy and simplification of the flight control chain. This article discusses the conceptual design of a distributed electric anti-torque system, starting from a reference usage spectrum and a theoretical architecture example. The goal is to optimize the key electrical components for steady-state operations and to verify the dynamic behaviour in healthy and degraded conditions. In addition, the resources introduced with the tail rotor electrification are considered to improve the aircraft performance in hot and high conditions. Following an introduction to the safety requirements and the electrical technology state-of-the-art, all the main components are modelled and combined into a single dynamic network. Simulation results from different testing scenarios are then reviewed (in the mechanical, thermal and electrical domain) to show compliance with the minimum acceptance criteria. Finally, the article discusses the advantages and disadvantages of a distributed versus concentrated electrical solution.