Integrated Design of a Morphing Winglet for Active Load Control and Alleviation of Turboprop Regional Aircraft

Ignazio Dimino,Frédéric Moens,Rosario Pecora,Giovanni Andreutti,Antonio Concilio,Federico Fonte

doi:10.3390/app11052439

Abstract

Aircraft winglets are well-established devices that improve aircraft fuel efficiency by enabling a higher lift over drag ratios and lower induced drag. Retrofitting winglets to existing aircraft also increases aircraft payload/range by the same order of the fuel burn savings, although the additional loads and moments imparted to the wing may impact structural interfaces, adding more weight to the wing. Winglet installation on aircraft wing influences numerous design parameters and requires a proper balance between aerodynamics and weight efficiency. Advanced dynamic aeroelastic analyses of the wing/winglet structure are also crucial for this assessment. Within the scope of the Clean Sky 2 REG IADP Airgreen 2 project, targeting novel technologies for next-generation regional aircraft, this paper deals with the integrated design of a full-scale morphing winglet for the purpose of improving aircraft aerodynamic efficiency in off-design flight conditions, lowering wing-bending moments due to maneuvers and increasing aircraft flight stability through morphing technology. A fault-tolerant morphing winglet architecture, based on two independent and asynchronous control surfaces with variable camber and differential settings, is presented. The system is designed to face different flight situations by a proper action on the movable control tabs. The potential for reducing wing and winglet loads by means of the winglet control surfaces is numerically assessed, along with the expected aerodynamic performance and the actuation systems’ integration in the winglet surface geometry. Such a device was designed by CIRA for regional aircraft installation, whereas the aerodynamic benefits and performance were estimated by ONERA on the natural laminar flow wing. An active load controller was developed by PoliMI and UniNA performed aeroelastic trade-offs and flutter calculations due to the coupling of winglet movable harmonics and aircraft wing bending and torsion.

Highlights

Morphing systems have been entered into aircraft design since the very first years of modern aviation [1,2]
Numerical Methods Used for Aerodynamic Performance Evaluation
It was found that such a device can be used as control surface on the aircraft for load alleviation, as a deflection of the tabs acts directly on the CL(α) curve

Summary

Introduction

Morphing systems have been entered into aircraft design since the very first years of modern aviation [1,2]. Studies continued, until the exceptional flight campaign carried out on the F111 in the 1980s and fully reported some years later, [5]. This is relevant, as the tested architecture on that evolved fighter was not dissimilar to Holle’s patent, dated some 60 years prior! The major product of this attention was the massive project “Adaptive Wing”, sponsored by DARPA and carried out by Northrop–Grumman, [7]. This effort may be acknowledged as the start of a new philosophy for aircraft adaptive systems. In [12], several morphing winglet concepts aiming to improve load control and wing aeroelastic response were investigated

Objectives

Methods

Results

Conclusion