Clean Sky 2: Exploring new rotorcraft high speed configurations

Abstract

This paper presents a multi-disciplinary overview description of a high speed compound helicopter configuration which is under development at Airbus Helicopters in cooperation with several European partners in the frame of the Clean Sky 2 research program. Clean Sky 2 is a European research program aiming to improve the efficiency of aeronautic transport. The specific project within Clean Sky 2, led by Airbus Helicopters, deals with the development and testing of an innovative rotorcraft demonstrator (RACER) which is developed for its high-speed capability particularly at the benefit of assistance to citizens (more efficiency for health & safety mission, door to doors transport…). The aim herein is to demonstrate the viability of a commercial aircraft on the basis of the concept validated in the recent past by the Airbus Helicopters X3 demonstrator. The high speed compound rotorcraft formula aims outstanding operational and economical enhancements in comparison to conventional helicopters exploiting the advantages of high-range, high-speed characteristics in combination with hovering capabilities whilst ensuring a high degree of safety and environmental friendliness. The paper mainly provides an overview of the global architecture of the Clean Sky 2 high speed vehicle in relation to its structure-mechanic, aerodynamic and aeromechanic performance. The paper first gives a brief introduction to the targets and organization of the Clean Sky 2 project which is followed by an overall description of the latest architectural characteristics of the high speed compound helicopter focusing on the new joined wing concept especially in comparison to mono-wing configurations. The main evolutions of the aircraft configuration and their associated improvements are highlighted. These improvements mainly refer, among other aspects, to enhanced safety, systems integration and definition (especially landing gear), payload ratio, aerodynamic performance (especially downwash), structure-mechanical characteristics as well as structural static and dynamic stiffness (especially in interaction with the dynamic system). The chosen detailed architecture is a result of the most efficient overall compromise on vehicle level regarding ambitious targets in terms of operational, tactical, economic, and safety aspects. The evolutionary configuration is underlined by a modern and unique layout and style.