Design and Development of a Four-Bladed Tail Rotor System for the USMC H-1 Upgrade Program

摘要

The USMC H-1 upgrade program was initiated to provide advanced aircraft configurations for the AH-1Z SuperCobra attack helicopters and UH-1Y Huey utility helicopters. The program includes development of a new four-bladed composite tail rotor system that provides higher aerodynamic performance, provides damage tolerant design with 10,000 hour life expectancy, and requires low maintenance through use of composites and elastomerics. The tail rotor assembly consists of two stacked two-bladed teetering rotors, mounted on a single output shaft. The design uses a composite twist strap flexure to accommodate collective pitch control, integral with each blade. One of the significant challenges involved with the design of the multi-bladed tail rotors is their ability to accommodate potentially powerful Coriolis torque. While various multi-bladed tail rotor designs, presently in use, compensate for this Coriolis torque differently, the proposed design offers a simpler and a cost-effective solution by making use of existing parts required to perform other functions. This paper presents the details of design, analyses, and structural testing of some of the key components of the tail rotor system. A summary of flight test results, to date, is also presented.