Canard Aircraft Research Articles

An Unsteady Reynolds–Averaged Navier–Stokes–Large Eddy Simulation Study of Propeller–Airframe Interaction in Distributed Electric Propulsion

A conceptual framework is presented to determine the improvement in the aerodynamic performance of a canard aircraft fitted with distributed propellers along its main wing. A preliminary study is described with four airframe–propeller configurations predominantly studied in academic and commercial designs. The leading edge–based tractors and trailing edge–based pushers are identified as configurations of interest for the main study. Subsequently, a Navier–Stokes solver is used to simulate the flow using two numerical approaches–a modified steady-state actuator disk and an unsteady rotating propeller profile. Moving meshes with rotating sub-domains are used with a hybrid RANS-LES-based turbulence model while the actuator disks are modified to include viscous swirl effects. The preliminary study shows a local minimum in the change in CL and CD at 10∘ for the pusher and tractor configurations. The main study then demonstrates the outperformance of the pushers over tractors quantified using CL and CL/CD. There is a clear preference for the pushers as they increase the lifting capacity of the aircraft without disproportionately increasing the drag due to the flow smoothening by the suction of the pusher propellers over the main wing. The pushers also delay the separation of the boundary layer whereas the tractors are unable to prevent the formation of the separation bubble despite injecting momentum through their slipstreams into the flow. The results from the two numerical approaches are then compared for accuracy in designing DEP configurations for an airframe.

Design and performance quantification of VTOL systems for a canard aircraft

AbstractThe design and performance quantification of four Vertical Take-Off and Landing (VTOL) architectures for a canard-type aircraft configuration are presented. The aero-structural sizing of the canard configuration and the sizing procedure for the proposed VTOL configurations are described and discussed. The proposed VTOL architectures are based on a range of rotor distances to the centre of gravity, quad- and tri-rotor configurations, retractable front rotors and tilt rear rotors. The aerodynamic performance, total installed power and VTOL system mass were modelled and experimentally validated. The results show that a fully exposed VTOL system penalises the Lift-over-Drag (L/D) ratio significantly relative to a clean configuration. The VTOL system mass can be reduced by up to 32% by using a tilt tri-rotor configuration when compared with an equidistant quad-rotor+pusher configuration. The fraction of installed power usable for forward flight can be increased by up to 80% with a tilt configuration. For the proposed mission, the range can be significantly increased if a tri-rotor tilt configuration is adopted in place of an equidistant quad-rotor+pusher configuration.

Performance Analysis and Visualization of Canard and Fuselage Effects on Flow Patterns around a Straight-Body-Type-Fuselage (SBTF) Fighter Models with Experimental Method in Water Tunnel

Performance analysis and visualization of canard and fuselage effects on flow patterns around an SBTF fighter model have been conducted. An SBTF fighter model with an experimental method in a water tunnel would easily reveal visually the vortex dynamics phenomenon that occurred. Testing has been done, with some form of non-canard and canard aircraft in a water tunnel, on vortex dynamics and aerodynamic power on the aircraft model. The stream demonstration used a fluid speed of 0.1 m/s and Reynolds number 6.577x103 on a 1:110 scale model and measured using dye injection method with a print ink type with a mixture ratio of 1:8. The result of the research using GAMA water tunnel showed the aerodynamic force and vortex dynamics phenomenon that happened on the model aircraft. The research on the benefits of the canard is also done by examining the performance and the flow visualization of an SBTF fighter without fuselage, with the symmetrical plane and with the regular fuselage in a water tunnel. The results showed that the use of canard affected the lift, drag, and flow pattern around the wings. The use of canard can enhance the lift of the plane and function to delay the stall by restoring the flow above the wing which should have experienced turbulence back into laminar so that the fighter can maneuver to a higher angle of attack (AoA) without stalling. It is identified that canard and fuselage play significant roles on the design of a fighter. The design choice of the fuselage and the employment of canard are fundamental to support the ability of maneuver and agility of the fighter.

Experimental Study and Neural Network Modeling of Aerodynamic Characteristics of Canard Aircraft at High Angles of Attack

Flow over an aircraft at high angles of attack is characterized by a combination of separated and vortical flows that interact with each other and with the airframe. As a result, there is a set of phenomena negatively affecting the aircraft’s performance, stability and control, namely, degradation of lifting force, nonlinear variation of pitching moment, positive damping, etc. Wind tunnel study of aerodynamic characteristics of a prospective transonic aircraft, which is in a canard configuration, is discussed in the paper. A three-stage experimental campaign was undertaken. In the first stage, a steady aerodynamic experiment was conducted. The influence of a reduced oscillation frequency and angle of attack on unsteady aerodynamic characteristics was studied in the second stage. In the third stage, forced large-amplitude oscillation tests were carried out for the detailed investigation of the unsteady aerodynamics in the extended flight envelope. The experimental results demonstrate the strongly nonlinear behavior of the aerodynamic characteristics because of canard vortex effects on the wing. The obtained data are used to design and test mathematical models of unsteady aerodynamics via different popular approaches, namely the Neural Network (NN) technique and the phenomenological state space modeling technique. Different NN architectures, namely feed-forward and recurrent, are considered and compared. Thorough analysis of the performance of the models revealed that the Recurrent Neural Network (RNN) is a universal approximation tool for modeling of dynamic processes with high generalization abilities.

A Study on Parameter Estimation for General Aviation Canard Aircraft

This paper presents the procedures used for estimating the stability and control derivatives of a general aviation canard aircraft from flight data. The maximum likelihood estimation method which accounts for both process and measurement noise was used for the flight data analysis of a four seat canard aircraft, the Firefly. Without relying on the parameter estimation method, several aerodynamic derivatives were obtained by analyzing the steady state flight data. A wind tunnel test, a flight test of a 1/4 scaled remotely controlled model aircraft, and the prediction of aerodynamic coefficients using the USAF Stability and Control Digital Data Compendium (DATCOM), Advanced Aircraft Analysis (AAA), and Computer Fluid Dynamics (CFD) were performed during the development phase of the Firefly and the results were compared with flight determined derivatives of a full scaled flight prototype. A correlation between the results from each method could be used for the design of the canard aircraft as well as for building the aerodynamic database.

Flight Dynamics Principles of Canard Aircraft: Implications for UAV Configuration Decision

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.

카나드 형상 고시동 항공기 공력설계를 우한 높은 받음각 정적 안정성 분석 실험 연구

During the conceptual design phase of a canard type high maneuverable aircraft, the low speed small scale wind tunnel test was conducted to investigate the high angle-of-attack static stability of the aircraft. In this study, 1/50th scale generic canard-body-wing model was used for the small scale wind tunnel test. For the analysis of static stability including high angle-of-attack nonlinear characteristics, the vertical tail effects were studied due to canard deflections. In addition, the nose chine effects were studied at high angle-of-attack. Based on the results obtained from the experimental study, the configuration change effects for canard type aircraft on high angle-of-attack static stability have been able to analyze.

소형 커나드 항공기의 가로안정성 향상에 관한 연구

본 논문에서는 소형 커나드 항공기인 Velocity-173의 가로안정성을 향상시키기 위한 방법에 대하여 연구하였다. Velocity-173의 세로안정성은 매우 우수한 반면, 가로안정성은 상대적으로 나쁘다. 가로안정성을 향상시키기 위해 수직미익의 면적을 증가시키는 작은 패널을 설계 및 제작하였다. 패널 설계 과정에서 AAA를 이용하여 패널 부착으로 인한 가로안정성의 변화를 예측하였다. 패널 부착 효과를 검증하기 위해 비행시험이 수행되었다. 또한, 비행시험 데이터로부터 안정/조종 미계수를 추출하기 위하여 최대공산추정법을 이용하였다. 본 연구를 통해 수직미익 아래에 부착된 패널의 효과를 확인할 수 있었다. This paper presents a method to improve lateral stability of a four-seat canard aircraft, Velocity-173. Longitudinal stability of Velocity-173 is rather good, but lateral stability is relatively poor. A small panel which increases the area of vertical tail is designed and manufactured. In a design process, AAA(Advanced Aircraft Analysis) is used to predict the change in stability. Flight test is performed to validate the effect of a small panel attached under the vertical panel. Maximum likelihood estimation method is used to extract lateral controllability / stability derivatives from flight test data. This work validates the effect of a small panel attached under the vertical tail.

Navier-Stokes Simulation of Close-Coupled Canard Aircraft Configuration Using Hybrid Unstructured CFD

Navier-Stokes Simulation of Close-Coupled Canard Aircraft Configuration Using Hybrid Unstructured CFD

비행시험을 통한 소형 커나드항공기의 비행 특성 연구

본 논문에서는 4인승 커나드 항공기에 측정 센서와 데이터 처리 장비를 장착하고, 비행 성능 시험을 수행하여 획득한 비행데이터를 분석하였다. 실속 시험을 통하여 주익 실속이 원천적으로 방지되는 커나드 항공기 고유의 안전성을 확인하였다. 상반각효과, 역 빗놀이 현상 및 롤 조종력을 살펴보았고, 종 안정성을 좌우하는 중립점 위치를 추정하였다. 더치롤모드 등의 동운종 특성도 분석하였다. 일반적인 변수추정방법을 사용하지 않고 정상비행 상태에서의 비행데이터로부터 공렬 미계수 값을 직접 추정하거나 공렬 미계수 간의 관계식을 구하였다. This paper presents the analysis of the flight test data measured by the sensors installed on a four-seat canard aircraft. The inherent stall proof characteristics of canard aircraft was verified from the stall test. The dihedral effect, adverse yaw and roll control power were examined and the neutral point that determines the longitudinal stability of the aircraft was investigated. The dynamic characteristics such as dutch roll mode were also examined. Without relying on the parameter identification method, the aerodynamic derivatives or the relations between the aerodynamic derivatives were obtained by analyzing the steady state flight data.

The design of a control system for an unstable canard aircraft using eigenstructure assignment

The problem of designing a control system for a nonlinear unstable canard aircraft is presented. Design performance criteria including robustness and pilot-handling qualities are discussed. The eigenstructure-assignment technique is used to determine the gains of a simple, practical system. The results of three designs are presented and show good handling and robustness qualities.

A look at handling qualities of canard configurations

The first human-powered flight was achieved by a canard-configured aircraft (Wright Brothers). Although other canard concepts were flown with varying degrees of success over the years, the tail-aft configuration has dominated the aircraft market for both military and civil use. Reviewed are the development of several canard aircraft with emphasis on stability and control, handling qualities, and operating problems. The results show that early canard concepts suffered adversely in flight behavior because of a lack of understanding of the sensitivities of these concepts to basic stability and control principles. Modern canard designs have been made competitive with tail-aft configurations by using appropriate handling qualities design criteria.

Aerodynamic canard/wing parametric analysis for general-aviation applications

Vortex panel and vortex lattice methods have been utilized in an analytic study to determine the two- and three-dimensional aerodynamic behavior of canard and wing configurations. The purpose was to generate data useful for the design of general aviation canard aircraft. Essentially no two-dimensional coupling was encountered and the vertical distance between the lifting surfaces was found to be the main contributor to interference effects of the three-dimensional analysis. All canard configurations were less efficient than a forward wing with an aft horizontal tail, but were less sensitive to off-optimum division of total lift between the two surfaces, such that trim drag could be less for canard configurations. For designing a general aviation canard aircraft, results point toward large horizontal and vertical distance between the canard and wing, a large wing-to-canard area ratio, and with the canard at a low incidence angle relative to the wing.

Aerodynamic design optimization trim analysis of canard conventionalconfigurations

A design study has been conducted to optimize trim cruise flight of high performance general aviation canard aircraft which achieve minimum drag. In order to investigate the advantages and disadvantages of canard configured aircraft, corresponding conventional tail-aft aircraft were designed and used for comparison. Two-dimensional coupled lift and drag coefficient predictions of the canard and wing airfoil shapes were obtained by coupling inviscid results from a vortex panel multielement program to a momentum integral boundary layer analysis. By using the results of the two-dimensional vortex panel analysis, a vortex lattice method was employed to predict the finite wing results. The analysis utilized a turbulent airfoil and a natural laminar airfoil, which are two NASA state-of-the-art airfoil sections. The canard aircraft designs give quantitative results of wing and canard loadings, wing-to-canard moment arm ratios, and aspect ratio effects for trim cruise flight for a wide range of wing-to-canard area ratios. Both canard and baseline aircraft achieved a 25-30% improvement in performance over typical current technology aircraft, but high canard loading necessary for trim resulted in slightly poorer cruise performance of the canard aircraft for equal fuel as compared to the baseline designs. However, when takeoff gross weight was held the same by reducing the fuel payload, the canard designs achieved longer ranges than the baselines. The required positive decalage angle between the canard and the wing guarantees that the canard will stall first, thereby preventing the wing from stalling, and thus having a stall- and, hence, spin-proof configuration.