Effects of Canard Surface Size on Stability and Control Characteristics of Two Canard Airplane Configurations at Mach Numbers of 1.41 and 2.01
Explore the source record for details and available documents.
Spearman, M Leroy↗
SEARCH · Search NASA
Results for “Canard”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Static Stability and Control of Canard Configurations at Mach Numbers from 0.70 to 2.22 : Lateral-directional Characteristics of a Triangular Wing and Canard
Explore the source record for details and available documents.
Peterson, Victor L↗
Static Stability and Control of Canard Configurations at Mach Numbers from 0.70 to 2.22 : Longitudinal Characteristics of a Triangular Wing and Canard
Explore the source record for details and available documents.
Boyd, John W↗
Numerical Study of Steady and Unsteady Canard-Wing-Body Aerodynamics
The use of canards in advanced aircraft for control and improved aerodynamic performance is a topic of continued interest and research. In addition to providing maneuver control and trim, the influence of canards on wing aerodynamics can often result in increased maximum lift and decreased trim drag. In many canard-configured aircraft, the main benefits of canards are realized during maneuver or other dynamic conditions. Therefore, the detailed study and understanding of canards requires the accurate prediction of the non-linear unsteady aerodynamics of such configurations. For close-coupled canards, the unsteady aerodynamic performance associated with the canard-wing interaction is of particular interest. The presence of a canard in close proximity to the wing results in a highly coupled canard-wing aerodynamic flowfield which can include downwash/upwash effects, vortex-vortex interactions and vortex-surface interactions. For unsteady conditions, these complexities of the canard-wing flowfield are further increased. The development and integration of advanced computational technologies provide for the time-accurate Navier-Stokes simulations of the steady and unsteady canard-wing-body flox,fields. Simulation, are performed for non-linear flight regimes at transonic Mach numbers and for a wide range of angles of attack. For the static configurations, the effects of canard positioning and fixed deflection angles on aerodynamic performance and canard-wing vortex interaction are considered. For non-static configurations, the analyses of the canard-wing body flowfield includes the unsteady aerodynamics associated with pitch-up ramp and pitch oscillatory motions of the entire geometry. The unsteady flowfield associated with moving canards which are typically used as primary control surfaces are considered as well. The steady and unsteady effects of the canard on surface pressure integrated forces and moments, and canard-wing vortex interaction are presented in detail including the effects of the canard on the static and dynamic stability characteristics. The current study provides an understanding of the steady and unsteady canard-wing-body flowfield. Emphasis is placed on the effects of the canard on aerodynamic performance as well as the detailed flow physics of the canard-wing flowfield interactions. The computational tools developed to accurately predict the time-accurate flowfield of moving canards provides for the capability of coupled fluids-controls simulations desired in the detailed design and analysis of advanced aircraft.
Eugene, L. Tu↗
Static longitudinal aerodynamic characteristics of close-coupled wing-canard configurations at Mach numbers from 1.60 to 2.86
An experimental investigation was made in the Mach number range from 1.60 to 2.86 to determine the static longitudinal aerodynamic characteristics of close-coupled wing-canard configurations. Three canards, ranging in exposed planform area from 17.5 to 30.0 percent of the wing reference area, were employed in this investigation. The canards were either located in the plane of the wing or in a position 18.5 percent of the wing mean geometric chord above the wing plane. Most data obtained were for a model with a 60 deg leading-edge-sweep wing; however, a small amount of data were obtained for a 44 deg leading-edge-sweep wing. The model utilized two balances to isolate interference effects between wing and canard. In general, it was determined that at angle of attack for all configurations investigated with the canard in the plane of the wing an unfavorable interference exists which causes the additional lift on the canard generated by a canard deflection to be lost on the wing due to an increased downwash at the wing from the canard. Further, this interference decreased somewhat with increasing Mach number. Raising the canard above the plane of the wing also greatly decreased the interference of the canard deflection on the wing lift. However, at Mach 2.86 the presence of the canard in the high position had a greater unfavorable interference effect at high angles of attack than the canard in the wing plane. This interference resulted in the in-plane canard having better trimmed performance at Mach 2.86 for the same center-of-gravity location.
Dollyhigh, S. M.↗
Longitudinal and Lateral Stability and Control Characteristics of Various Combinations of the Component Parts of Two Canard Airplane Configurations at Mach Numbers of 1.41 and 2.01
An investigation has been conducted in the Langley 4- by 4-foot supersonic pressure tunnel to determine the aerodynamic characteristics in pitch and sideslip of a generalized canard airplane model. Two wings of equal area but differing in plan form were investigated. The model was equipped with a trapezoidal canard surface with an area 12 percent of the wing area, a low-aspect-ratio vertical tail, and twin ventral fins. The interference effects of the canard wake on the wing result in little or no gain in the total lift at a Mach number of 1.41 but at a Mach number of 2.01 a substantial portion of the canard lift is retained with a resultant increase in total lift. Because these interference effects of the canard wake appear to be concentrated near the leading edge of the wing, the proper location of the wing leading edge with respect to the center of moments may result in a substantial increase in the moment increment provided by a canard surface even though the total lift provided by the canard is small. For these configurations the trapezoidal wing retained the most lift and had the largest favorable moment increment produced by the canards. The canard configurations have the same characteristic decrease in directional-stability with angle of attack as most conventional high-fineness-ratio supersonic configurations. Although the presence of the canard surface caused a small increase in the directional stability at a Mach number of 1.41 for the delta-wing configuration, the presence of the canards resulted in small decreases in the directional-stability level at a Mach number of 2.01 for both wing configurations. A canard deflection of 15 deg provides an increase in the positive effective dihedral approximately as large as that provided by the presence of the vertical tail. This effect of canard deflection might complicate the lateral-control problem in the case of a rolling pull-up maneuver.
Driver, Cornelius↗
Canard-wing lift interference related to maneuvering aircraft at subsonic speeds
An investigation was conducted at Mach numbers of 0.7 and 0.9 to determine the lift interference effect of canard location on wing planforms typical of maneuvering fighter configurations. The canard had an exposed area of 16.0 percent of the wing reference area and was located in the plane of the wing or in a position 18.5 percent of the wing mean geometric chord above the wing plane. In addition, the canard could be located at two longitudinal stations. Two different wing planforms were tested: one with a leading-edge sweep angle of 60 deg and the other with a leading-edge sweep angle of 44 deg. The results indicated that although downwash from the canard reduced the wing lift at angles of attack up to approximately 16 deg, the total lift was substantially greater with the canard on than with the canard off. At angles of attack above 16 deg, the canard delayed the wing stall. Changing canard deflection had essentially no effect on the total lift, since the additional lift generated by the canard deflection was lost on the wing due to an increased downwash at the wing from the canard.
Gloss, B. B.↗
The effect of canard and vertical tails on the aerodynamic characteristics of a model with a 59 deg sweptback wing at a Mach number of 0.30
An investigation has been conducted to determine the effects of canard, canard location, vertical tails, and vertical-tail location on the aerodynamic characteristics of a model having a 59 deg sweptback wing. The investigation was conducted at a Mach number of 0.30, at angles of attack up to 22 deg and at sideslip angles of 0 deg and plus or minus 5 deg. The results of the study indicate that adding the canard to the model had only a slight effect on the lift at the lower angles of attack. At the higher angles of attack there is a significant effect of canard height on lift, canard in the high location (above the wing chord plane) resulting in the highest lifts. The lift drag characteristics are predicted well for the configuration with the mid or high canard locations by combining a potential flow solution on the canard with a potential plus vortex solution on the wing. Variations in the height significantly affect the pitching-moment characteristics of the configuration; the configuration with the low or mid canard location exhibits an increase in stability at the higher lift coefficients, whereas the configuration with the high canard exhibits pitch-up. Adding the vertical tails in the outboard location caused a significant loss in lift at the higher angles of attack; this lift loss was eliminated by moving the vertical tails inboard.
Henderson, W. P.↗
Aerodynamic optimization, comparison, and trim design of canard and conventional high performance general aviation configurations
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 'baseline' aircraft were designed and used for comparison. Two-dimensional predictions were obtained by coupling inviscid results from a vortex panel multi-element program to a momentum integral boundary layer analysis. 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 to 30 percent improvement in performance over typical current technology aircraft, but high canard loading necessary for trim resulted in slightly poorer performance of the canard aircraft as compared to the baseline designs.
Keith, M. W.↗
The effects of canard-wing flow-field interactions on longitudinal stability, effective dihedral and potential deep-stall trim
The literature available on high aspect ratio canard configurations shows them to have some unique stability characteristics. Using a generic canard-wing model, the effects of canard-wing flow-field interactions on stability were investigated in the NASA Langley Twelve-Foot Low-Speed Wind Tunnel. Results for the attached flow regime indicate linear interactions shift the neutral point of a canard configuration forward, but the effect of a canard on a wing can change significantly when the flow over the surface begins to separate, even several degrees below stall. The asymmetry of the canard downwash in a sideslip condition can result in an increment in effective dihedral roughly proportional to canard lift coefficient. At very high angles of attack the presence of a wing can cause an incremental normal force on a canard, contributing to the possibility of a deep-stall trim point. This effect is greater for a high canard and less for a low one.
Muchmore, C. B., Jr.↗
Navier-Stokes Simulation of the Canard-Wing-Body Longitudinal Dynamic Stability Characteristics
Many modern aircraft are canard-configured for aircraft control and improved aerodynamic performance. Canards can often enhance aircraft cruise performance, maneuverability and agility. For close-coupled canard configurations, the aerodynamic interaction between the canard and wing significantly changes the flow characteristics of the wing. In unsteady flow, such changes in the flow structure and performance of wings can be quite pronounced. Accurate modeling of the unsteady aerodynamics is essential for potential CFD design and analysis of such configurations. A time-accurate numerical simulation is performed to study the unsteady aerodynamic interaction between a canard and wing with emphasis on the effects of the canard on the configuration's dynamic response characteristics. The thin-layer Reynolds-averaged Navier-Stokes Equations with various turbulence models are used in this study. Computations are made on a generic, analytically-defined, close-coupled canard-wing-body configuration which has been the subject of numerous previously published experimental studies during the 1970's to mid-80's. More recently, a series of steady-flow simulations has been performed and published by the author. In the current study, the configuration is given prescribed ramp and oscillatory motions in order to predict characteristics such as the damping-in-pitch and oscillatory longitudinal stability parameters. The current computations are made at high-subsonic and transonic Mach numbers, moderate angles-of- attack from -4 to 20 degrees, and at various pitch rates and reduced frequencies. Comparisons of pressures and integrated force quantities (e.g. lift, drag, pitching moment and selected dynamic parameters) are made with other published computational results and available experimental data. Results showing the unsteady effects of the canard on surface pressures, integrated forces, canard-wing vortex interaction and vortex breakdown will be presented.
Tu, Eugene L.↗
A study of canard-wing interference using experimental pressure data at transonic speeds
The canard had an exposed area of 28.0 percent of the wing reference area and was located in the chord plane of the wing or in a position 18.5 percent of the wing mean geometric chord above or below the wing chord plane. The canard leading edge sweep was 51.7 deg and the wing leading-edge sweep was 60 deg. The results indicated that the direct canard downwash effects on the wing loading are limited to the forward half of the wing directly behind the canard. The wing leading-edge vortex is located farther forward for the wing in the presence of the canard than for the wing-alone configuration. The wake, from the canard located below the wing chord plane, physically interacts with the wing inboard surface and produces a substantial loss of wing lift. For the Mach number 0.70 case, the presence of the wing increased the loading on the canard for the higher angles of attack. However, at Mach numbers of 0.95 and 1.20, the presence of the wing had the unexpected result of unloading the canard.
Gloss, B. B.↗
Navier-Stokes simulation of a close-coupled canard-wing-body configuration
The thin-layer Navier-Stokes equations are solved for the flow about a coplanar close-coupled canard-wing-body configuration at a transonic Mach number of 0.90 and at angles of attack ranging from 0 to 12 degrees. The influence of the canard on the wing flowfield, including canard-wing vortex interaction and wing vortex breakdown, is investigated. A study of canard downwash and canard leading-edge vortex effects, which are the primary mechanisms of the canard-wing interaction, is emphasized. Comparisons between the computations and experimental measurements of surface pressure coefficients, lift, drag and pitching moment data are favorable. A grid refinement study for configurations with and without canard shows that accurate results are obtained using a refined grid for angles of attack where vortex burst is present. At an angle of attack of approximately 12 deg, favorable canard-wing interaction which delays wing vortex breakdown is indicated by the computations and is in good agreement with experimental findings.
Tu, Eugene L.↗
An Experimental Investigation of the Effect of a Canard Control on the Lift, Drag, and Pitching Moment of an Aspect-Ratio 2.0 Triangular Wing Incorporating a Form of Conical Camber
The results of an experimental investigation to determine the effect of a canard control on the lift, drag, and pitching-moment characteristics of an aspect-ratio-2.0 triangular wing incorporating a form of conical camber are presented. The canard had a triangular plan form of aspect ratio 2.0 and was mounted in the extended chord plane of the wing. The ratio of the area of the exposed canard panels to the total wing area was 6.9 percent, and the ratio of the total areas was 12.9 percent. Data were obtained at Mach numbers from 0.70 to 2.22 through an angle-of-attack range from -6 deg to +18 deg with the canard on, and with the canard off. To provide a basis for comparison, the canard was also tested with a symmetrical wing having the same plan form, aspect ratio, and thickness distribution as the cambered wing. The results of the investigation showed that at the high subsonic speeds the gain in maximum lift-drag ratio achieved by camber was considerably reduced by the addition of a canard. At the supersonic speeds, the addition of the canard did not change the effect of camber on the maximum lift-drag ratios.
Menees, Gene P.↗
The Static Longitudinal Stability and Control Characteristics in the Presence of the Ground of a Model Having a Triangular Wing and Canard
A wind-tunnel investigation was made of the low-speed characteristics of a canard configuration having triangular wing and canard surfaces with an aspect ratio of 2. The exposed area of the canard was 6.9 percent of the total wing area. The canard hinge line was located at 0.35 of its mean aerodynamic chord and was 0.5 wing mean aerodynamic chord lengths forward of the wing apex. The ground effects, which made the lift more positive and the -Pitching moment more negative at a given angle of attack, were unaffected by the canard. The stability of the model at a constant canard hinge-moment coefficient decreased to 0 near a lift coefficient of 1.0. In addition, the maximum lift coefficient at which the canard could provide balance was decreased by ground effects to less than 1.0 if the moment center was as far forward as 0.21 of the wing mean aerodynamic chord. The relative magnitude of interference effects between the canard and the wing and body is presented.
Buell, Donald A.↗
Effect of canard position and wing leading-edge flap deflection on wing buffet at transonic speeds
A generalized wind-tunnel model, with canard and wing planform typical of highly maneuverable aircraft, was tested. The addition of a canard above the wing chord plane, for the configuration with leading-edge flaps undeflected, produced substantially higher total configuration lift coefficients before buffet onset than the configuration with the canard off and leading-edge flaps undeflected. The wing buffet intensity was substantially lower for the canard-wing configuration than the wing-alone configuration. The low-canard configuration generally displayed the poorest buffet characteristics. Deflecting the wing leading-edge flaps substantially improved the wing buffet characteristics for canard-off configurations. The addition of the high canard did not appear to substantially improve the wing buffet characteristics of the wing with leading-edge flaps deflected.
Gloss, B. B.↗
Effects of canard location on the aerodynamic characteristics of a blunt-nosed missile at Mach numbers of 1.5 and 2.0
A blunt-nosed missile model with nose-mounted canards and cruciform tail surfaces was tested in the Ames 6 by 6-Foot Wind Tunnel to determine the contributions of the component aerodynamic surfaces to the static aerodynamic characteristics at Mach numbers of 1.5 and 2.0 and Reynolds number of 1 million based on body diameter. Data were obtained at angles of attack ranging from -3 deg to 12 deg and canard-deflection angles from -3 deg to 15 deg for various stages of model build-up (i.e., with and without canard and/or tail surfaces). Results were obtained with the canards at two different nose locations. For the canard and tail arrangements investigated, the model was trimmable at angles of attack up to about 4 deg or 5 deg with canard deflections of 9 deg. For this blunt-nosed model, there was little effect of canard location on trim angle of attack. The tail arrangements studied provided ample pitch stability.
Kassner, D. L.↗
Investigation at High Subsonic Speeds of the Static Longitudinal and Lateral Stability Characteristics of Two Canard Airplane Configurations
The present investigation was conducted in the Langley high-speed 7-by 10-foot tunnel to determine the static longitudinal and lateral stability characteristics at high subsonic speeds of two canard airplane configurations previously tested at supersonic speeds. The Mach number range of this investigation extended from 0.60 to 0.94 and a maximum angle-of-attack range of -2dewg to 24deg was obtained at the lowest test Mach number. Two wing plan forms of equal area were studied in the present tests; one was a 60deg delta wing and the other was a trapezoid wing having an aspect ratio of 3, taper ratio of 0.143, and an unswept 80-percent-chord line. The canard control had a trapezoidal plan form and its area was approximately 11.5 percent of the wing area. The model also had a low-aspect-ratio highly swept vertical tail and twin ventral fins. The longitudinal control characteristics of the models were consistent with past experience at low speed on canard configurations in that stalling of the canard surface occurred at moderate and high control deflections for moderate values of angle of attack. This stalling could impose appreciable limitations on the maximum trim-lift coefficient attainable. The control effectiveness and maximum value of trim-lift was significantly increased by addition of a body flap having a conical shape and located slightly behind the canard surface on the bottom of the body. Addition of the canard surface at 0deg deflection had relatively little effect on overall directional stability of the delta-wing configuration; however, deflection of the canard surface from 0deg to 10deg had a large favorable effect on directional stability at high angles of attack for both the trapezoid- and delta-wing configurations.
Sleeman, William C., Jr.↗