A Differential Configuration of Split Drag-Rudders with Variable Bias for Directional Control of Flying-Wing

2014 ◽  
Vol 643 ◽  
pp. 54-59 ◽  
Author(s):  
Jahanzeb Rajput ◽  
Wei Guo Zhang ◽  
Xiao Bo Qu
Keyword(s):  
Cfd Simulation ◽  
Angle Of Attack ◽  
Large Angle ◽  
Simple Method ◽  
Low Speed ◽  
Control Efficiency ◽  
Stability And Control ◽  
Directional Stability ◽  
Variable Bias ◽  
And Control

The directional stability and control is crucial for the low-speed flight of a flying-wing aircraft. The split drag-rudders are well known devices used to provide directional stability and control in a flying-wing aircraft. As opposed to conventional rudders, the control efficiency of split drag-rudders is typically low for small deflection-angles and the influence on yawing moment is nonlinear. Such characteristics limit the control capability of split drag-rudders at low speed flight with large angle-of-attack. In this paper, a simple method is presented to improve the control efficiency of split drag-rudders at low speed flight with large angle-of-attack. The method is based on a strictly differential configuration of split drag-rudders which operates around a certain variable bias. The bias can be varied according to different flight conditions in order to achieve desired performance. The CFD simulation results are presented in support of this concept. Results also show that the proposed configuration has linearizing effects on yawing moment vs. deflection curves, which may prove helpful in control system design process. The possible control reversal in yaw at large angle of attack can also be avoided with this method.

Effects of Aircraft Tail Configurations on Sensitivity to Yaw Disturbances

2014 ◽  
Vol 629 ◽  
pp. 197-201 ◽  
Author(s):  
Nur Amalina Musa ◽  
S. Mansor ◽  
Airi Ali ◽  
Wan Zaidi Wan Omar ◽  
Ainullotfi Abdul Latif ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Low Speed ◽  
Stability And Control ◽  
Directional Stability ◽  
And Control ◽  
Low Speed Wind Tunnel ◽  
Yaw Moment ◽  
Made In

A wind tunnel test was conducted to compare the characteristics of low speed stability and control for aircraft with conventional tail and V-tail configurations. Comparison was made in terms of static directional stability at selected test speed of 40 m/s, which corresponds to Reynolds number of 0.1622 x 106 based on the chord. Three types of simplified tail-only model were tested in Universiti Teknologi Malaysia's Low Speed Wind Tunnel (UTM-LST). Results show that the V-tail configuration greatly affects the aerodynamic characteristics in directional stability as the side force and yaw moment tends to vary linearly with yaw angles up to 25 degrees, compared to conventional tail that has linear characteristics up to only 10 degrees yaw

scholarly journals Aerodynamic characteristics of a feathered dinosaur measured using physical models. Effects of form on static stability and control effectiveness.

2013 ◽  
Author(s):  
Dennis Evangelista ◽  
Griselda Cardona ◽  
Eric Guenther-Gleason ◽  
Tony Huynh ◽  
Austin Kwong ◽  
...  
Keyword(s):  
Flight Control ◽  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
Static Stability ◽  
Physical Models ◽  
Stability And Control ◽  
Control Effectiveness ◽  
Biomechanical Constraints ◽  
Lift And Drag ◽  
And Control

We report the effects of posture and morphology on the static aerodynamic stability and control effectiveness of physical models based on the feathered dinosaur,Microraptor gui, from the Cretaceous of China. Postures had similar lift and drag coefficients and were broadly similar when simplified metrics of gliding were considered, but they exhibited different stability characteristics depending on the position of the legs and the presence of feathers on the legs and the tail. Both stability and the function of appendages in generating maneuvering forces and torques changed as the glide angle or angle of attack were changed. These are significant because they represent an aerial environment that may have shifted during the evolution of directed aerial descent and other aerial behaviors. Certain movements were particularly effective (symmetric movements of the wings and tail in pitch, asymmetric wing movements, some tail movements). Other appendages altered their function from creating yaws at high angle of attack to rolls at low angle of attack, or reversed their function entirely. WhileM. guilived afterArchaeopteryxand likely represents a side experiment with feathered morphology, the general patterns of stability and control effectiveness suggested from the manipulations of forelimb, hindlimb and tail morphology here may help understand the evolution of flight control aerodynamics in vertebrates. Though these results rest on a single specimen, as further fossils with different morphologies tested, the findings here could be applied in a phylogenetic context to reveal biomechanical constraints on extinct flyers arising from the need to maneuver. Now published in PLOS ONE http://dx.plos.org/10.1371/journal.pone.0085203

scholarly journals DEFINITION THE STABILITY AND CONTROL DERIVATIVES IN THE LONGITUDINAL CHANNEL OF SMALL SUBSONIC UAV

2013 ◽  
pp. 55-68
Author(s):  
О. В. Збруцький ◽  
Р. В. Карнаушенко ◽  
О. П. Мариношенко
Keyword(s):  
Angular Velocity ◽  
Speed Of Sound ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Kinematic Parameters ◽  
Stability And Control ◽  
Control Derivatives ◽  
The Stability ◽  
And Control ◽  
Longitudinal Channel

The problems of determining the stability and control derivatives of small subsonic UAV in the longitudinal channel are solved.An approach to the stability and control derivatives determination based on the analysis results of wind tunnel investigation and analyzes conducted .To the longitudinal movement usually referred traffic aircraft where it is in the plane of symmetry of one and the same vertical plane. Thus the aerodynamic lateral force, rolling moment and yaw angles of heel and slip and angular velocity of roll and glide zero. To investigate the longitudinal motion of the aircraft (movement in the longitudinal channel) important issue is to determine the components of the aerodynamic forces and moments as a function of the kinematic parameters of the flight, the so-called aerodynamic derivatives.Given that the object is a lightweight UAV that has subsonic range of operating speeds, significantly less than the speed of sound, it should be noted that the derivative of the coefficient of lift coefficient and drag coefficient for longitudinal moment of flight speed can be taken to be zero at subsonic speed range. This is due to the fact that these values are almost constant with airspeed , lower the speed of sound . Change the value of these parameters with growth rate appears only when approaching the speed of sound, due to changes in the position of the center of pressure and the additional impedance. Also, when calculating stability derivatives are generally neglected by changing the drag because the drag value of derivatives are small and commensurate with the error of the calculation methods.Derivatives of lift coefficient by the following kinematic parameters: angle of attack, the angular velocity of rotation around the transverse axis , rate of change of angle of attack and angle of elevator deflection are defined.Obtained results make it possible to analyze the movement of the UAV in the longitudinal channel and determinate the coefficients of a mathematical model of the UAV. Also possible  to determinate the stability and controllability of the UAV during automatic control systems design.

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