Flight dynamics principles of canard aircraft: Implications for UAV configuration decision

Headnote

Abstract: Marques P, Maligno A, Dierks S and Bachouche A. (2013). Flight dynamics principles of canard aircraft: Implications for UAV configuration decision. International Journal of Unmanned Systems Engineering. 1(2): 12-30. The canard configuration is an appealing alternative to the conventional aft tailplane stabiliser in the design of novel unmanned aerial vehicle (UAV) concepts. A canard foreplane increases the maximum lift coefficient and reduces the trim drag of the aircraft, making the canard set up particularly suitable for high-altitude long-endurance (HALE) UAVs. The inherent flight instability of canard-configured aircraft can be exploited to augment the manoeuvrability of advanced military UAVs at high angles of attack. Canard-wing arrangements result in complex strongly-coupled aerodynamic flow fields that include upwash-downwash effects, vortex-vortex interactions and vortex-surface interactions. This review paper provides a historical overview of the development of the canard aircraft, compares different canard airframes, explores the aerodynamics and aeroelasticity of canard aircraft, assesses longitudinal stability in conventional and canard arrangements, evaluates the aerodynamic efficiency of the tandem wing configuration, and gives examples of canard UAV platform development. The aerodynamic features of the Buraq HALE UAV canard prototype by Tunisia Aero Technologies Industries - UK are outlined. The paper also discusses the advantages and disadvantages of the canard configuration that inform the decision process in the development of next-generation UAV configurations. © Marques Aviation Ltd - Press.

Keywords:

Close-coupled canard

Flight dynamics

Non-conical vortex

Unsteady aerodynamics

Vortex-vortex interaction

1. INTRODUCTION

A canard is a lifting plane positioned in front of the main wing that serves as the horizon- tal stabiliser for stability in pitch of the aircraft.[1] Canards are an alternative to the conventional aft tailplane stabiliser. The use of a foreplane increases the maximum lift coefficient and reduces the trim drag of the aircraft.[2] The canard also provides safe enhanced stall control. Canards are tradi- tionally considered to be inherently unstable; however, static and dynamic stability can be achieved with careful foreplane design and positioning relative to the main wing.[3] Improvements in numerical techniques and accurate prediction of non-linear unsteady aerodynamics, coupled with developments in automatic flight control systems, has led to enhanced flight dynamics and manoeu- vrability of canard-configured aircraft.[4] Therefore, the negative static stability of canard configurations is used to advantage to augment aircraft agility...