Numerical Study of Aerodynamics and Effectiveness of Helicopter Double Row and Co-rotating Tail Rotors Concepts in Hover Modes
Authors: Makeev P.V.
Published in issue: #2(170)/2026
Category: Aviation and Rocket-Space Engineering | Chapter: Aerodynamics and Heat Transfer Processes in Aircrafts
The article presents the results of a study of the aerodynamic characteristics of a double-row tail rotor (DRTR) and a coaxial tail rotor (CTR), whose concept is based on the original tail rotor scheme of the TsAGI-1EA experimental helicopter (1930). The considered DRTR/CTR consists of a pair of separate two-bladed modules with combined horizontal hinges (HH), installed, unlike conventional tail rotors (TR), on the same axis from different sides (right and left) of the helicopter tail boom. The DRTR/CTR is compared with the existing promising scissors tail rotor of the Mi-8/17 family of helicopters and is based on its geometry. The separation of the rotation planes of the DRTR/CTR blade pairs is 0.83R. Two variants of the direction of rotation of the pairs of blades were considered: co-rotating (DRTR) and counter-rotating (CTR). For rotors in an isolated case without the influence of the vertical tail and main rotor (MR), hovering modes are considered, where a significant separation of the planes of rotation of the rotor blades makes it possible to maximize the positive aerodynamic effect characteristic of classic coaxial MR helicopters of the “Kamov” brand. The study was performed on the basis of a free wake model of a rotor. The shapes of the vortex wake, the flow patterns of the rotor, and the dependences of the distributed and total aerodynamic characteristics are constructed and analyzed. In hovering modes, the rotors considered demonstrate a significant increase in Figure of Merit, amounting to up to +10% for DRTR, and up to +11.3% for CTR compared with the scissors TR. The considered types of DRTR and CTR can be used on single-rotor helicopters for significantly increasing the reserves of control, reducing power costs, and improving flight safety.
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