Examining the stability derivatives of a compound helicopter

Ferguson, K. and Thomson, D. (2017) Examining the stability derivatives of a compound helicopter. Aeronautical Journal, 171(1235), pp. 1-20. (doi: 10.1017/aer.2016.101)

Abstract

Some helicopter manufacturers are exploring the compound helicopter design as it could potentially satisfy the new emerging requirements placed on the next generation of rotorcraft. It is well understood that the main benefit of the compound helicopter is its ability to reach speeds that significantly surpass the conventional helicopter. However, it is possible that the introduction of compounding may lead to a vehicle with significantly different flight characteristics when compared to a conventional helicopter. One method to examine the flight dynamics of an aircraft is to create a linearised mathematical model of the aircraft and to investigate the stability derivatives of the vehicle. The aim of this paper is to examine the stability derivatives of a compound helicopter through a comparison with a conventional helicopter. By taking this approach, some stability, handling qualities and design issues associated with the compound helicopter can be identified. The paper features a conventional helicopter and a compound helicopter. The conventional helicopter is a standard design, featuring a main rotor and a tail-rotor. The compound helicopter configuration features both lift and thrust compounding. The wing offloads the main rotor at high speeds, whereas two propellers provide additional propulsive thrust as well as yaw control. The results highlight that the bare airframe compound helicopter would require a larger tailplane surface to ensure acceptable longitudinal handling qualities in forward flight. In addition, without increasing the size of the bare airframe compound helicopter’s vertical fin, the Dutch roll mode satisfies the ADS-33 level 1 handling qualities category for the majority of the flight envelope.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Ferguson, Dr Kevin and Thomson, Dr Douglas
• Authors: Ferguson, K., and Thomson, D.
• College/School: College of Science and Engineering > School of Engineering > Autonomous Systems and Connectivity
• Journal Name: Aeronautical Journal
• Publisher: Cambridge University Press
• ISSN: 0001-9240
• ISSN (Online): 2059-6464
• Published Online: 20 October 2016
• Copyright Holders: Copyright © 2016 Royal Aeronautical Society
• First Published: First published in Aeronautical Journal 121(1235):1-20
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher