Final Report: Minimum Power Requirements and Optimal Rotor Design for Conventional and Compound Helicopters Using Higher Harmonic Blade Root Control
Abstract
The goal of this research is to understand the fundamental limits of the performance of real helicopter rotors, and the benefits of higher harmonic control (HHC) for applications involving conventional helicopter configurations, coaxial counter rotating rotors, and compound helicopters. We seek to answer the following questions: If one has limited control inputs to the rotor, what is the optimal performance, how close is the constrained input optimum to the rubber rotor optimum, and what periodic control inputs and fixed rotor geometry are required to achieve the optimum? In this work, we develop numerical tools, based on a variational approach, for finding the optimal design and resulting performance of helicopter rotors in cruise and hover, and also rotors designed for efficient operation at multiple flight conditions. The aerodynamic models are based on a vortex-lattice model for forward flight, blade element momentum theory for hover, with C81 tables to model compressible and viscous losses. We show that for conventional and coaxial counter rotating rotors, using radially varying twist and chord distributions and higher harmonic blade pitch control can produce significant reductions in required power, especially at high advance ratios.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 22, 2016
- Accession Number
- AD1063410
Entities
People
- Eli B. Giovanetti
- Kenneth C. Hall
Organizations
- Duke University