Investigating Power Benefits for a Helicopter by Variation of the Anti-Torque Device

Abstract

With the usage of electrically driven devices, the rigid connection between main rotor and tail rotor can be broken up, allowing for a tail section that can possibly be optimized for different operating conditions. This paper presents the results of a study investigating the power benefits of different variations of the electric anti-torque device. The investigations were performed using an engineering model of a main rotor - tail rotor helicopter built up in the Versatile Aeromechanics Simulation Tool (VAST). The studied variations include horizontal and vertical tilting of the tail rotor, changing tail rotor speed and fin angle as well as fin size and geometry. Various flight conditions such as hover, forward flight, quartering flight, climb, and descent have been investigated. The largest power benefits were observed for (1) a combination of reduced tail rotor speed and a fin angle varying between 12 deg for low speed forward flight and 6 deg for high flight speeds and (2) an increased fin area with the tail rotor being shut off for flight speeds above 35 m/s.