Wing Tail Research Articles

Using numerical simulation methods to analyze the aerodynamic performance of racing tail fins under multiple factor conditions

Abstract. In high-speed ground racing cars, the aerodynamics of the tail wing are crucial as they directly affect the overall performance and results of the car. In the aerodynamic performance of the tail wing, down force and drag are the two most important parameters. In order to study the specific effects of factors such as racing speed, tail wing profile, and tail angle of attack on the aerodynamic performance of the tail wing, fluid dynamics numerical simulation methods were used for research.The research results indicate that within the parameter range of 160km/h to 240 km/h, both resistance and down force continuously increase with the increase of speed, and show a typical linear variation pattern. Within the range of 0 to 35 angle of attack, both drag and down force increase, but within 20 , the increase in down force is faster, and once it exceeds 20 , the increase in drag becomes more pronounced.At the same time, four different airfoil structures were compared and analyzed, and it was concluded that the NACA airfoil is more suitable for low-speed operating conditions, as it can generate higher down force at lower speeds. The research results of this article provide certain reference value for the design and finalization of racing tail fins.

Optimal Selection of Active Jet Parameters for a Ducted Tail Wing Aimed at Improving Aerodynamic Performance

The foldable tail of the box-type launch vehicle poses a risk of mechanical jamming during the launch process, which is not conducive to the smooth completion of the flight mission. The integrated nonfolding ducted tail proposed in this article can solve the problem of storing the tail in the launch box. Moreover, traditional mechanical control surfaces have been eliminated, and active jet control has been adopted to control the pitch direction of the flight attitude, which can improve the structural reliability of the tail wing. By studying the effects of parameters such as momentum coefficient, jet hole position, jet hole height, and jet angle on improving the aerodynamic performance of ducted tail wing, relatively good jet parameters are selected. Research has found that compared with jet hole height and jet angle, momentum coefficient and jet hole position are more effective in improving the aerodynamic performance of ducted tail wings. Under a trailing edge jet, a relatively good jet condition occurs when the jet hole height is equal to0.25% of the aerodynamic chord length, and the jet angle is equal to 0°. At this time, with the increase of the jet momentum coefficient, the effect of increasing the lift of the ducted tail wing is the best. Finally, a comparative analysis is conducted on the lift and drag characteristics between the ducted tail wing and traditional tail wing, and it is found that the ducted tail wing can generate lift at a 0° attack angle and will not stall in the high attack angle range of 12°~22°, with broad application prospects.

Study of the Dynamic Processes of Multi-point Initiation of Co-axial Explosively Formed Projectiles with Tail Wings Using High Speed Image Processing Technologies

Study of the Dynamic Processes of Multi-point Initiation of Co-axial Explosively Formed Projectiles with Tail Wings Using High Speed Image Processing Technologies

Tiltwing eVTOL Transition Trajectory Optimization

This paper studies transition trajectory optimization for a tiltwing electrical vertical takeoff and landing (eVTOL) aircraft configuration and evaluates the benefits of equipping it with fluid injection active flow control (AFC). Using a three-degree-of-freedom model of the aircraft’s longitudinal dynamics, both hover-to-cruise (forward) and cruise-to-hover (backward) transition are investigated for a range of center-of-gravity (CG) positions to determine minimum-energy trajectories that achieve zero altitude variation while avoiding wing aerodynamic stall. It is demonstrated that constant-altitude transition can be achieved in the forward direction (with or without AFC), whereas the use of AFC in backward transition reduces the total altitude change by 24%. A comparative constant-altitude backward transition solution using a different airfoil with a higher stall limit suggests that a redesign of the tail wing of this unique tiltwing aircraft could better leverage the benefits of using AFC in this application. Additionally, it is also shown that, in the case of forward transition, AFC can be used to decrease the total transition time and increase the range of CG positions where constant-altitude transition can occur.

Modeling and Analysis of Kamikaze UAV Design with 3 Different Wing Configurations

Appropriate design parameters need to be determined for unmanned aerial vehicles that can perform kamikaze missions. In this study, a UAV with 3 different wing configurations and a fuselage and tail wings were designed, and the flow around the wing was examined using computational fluid mechanics. Advanced modeling techniques were employed to simulate and analyze the aerodynamic behavior of these configurations. The effect of angle of attack (AoA), wing positioning on the fuselage, and wing configurations were investigated. Due to the effect of the wing sweep angle, high-pressure values in the arrow-angle wing were lower than in rectangular and trapezoidal wings. In a similar situation, the flow separation on the arrow-angle wing is less advanced towards the wing tip. When the wing type and connection location were examined, the highest ${{C}_{l}}/{{C}_{d}}$ ratio was obtained in the trapezoidal model connected to the fuselage in the middle. The results of numerical wing models compared with the theoretical lift coefficient were consistent. Trapezoidal and rectangular wings had a high lift coefficient, but after ${{15}^{\circ }}$ of AoA, the lift coefficient decreased. At angles of attack beyond ${{15}^{\circ }}$, the arrow-angle wing still has an increasing lift coefficient. As the angle of attack increased, the drag coefficient was also enhanced. The lowest drag coefficient occurred in the arrow-angle wing model. Up to ${{5}^{\circ }}$of AoA, all wing models raised the ${{C}_{l}}/{{C}_{d}}$ ratio. The ${{C}_{l}}/{{C}_{d}}$ ratio decreased at higher angles of attack. As a result of the examination, it would be more correct to choose trapezoidal and arrow-angle wings.

Enhancing Longitudinal Flight Performance of Drones through the Coupling of Wings Morphing and Deflection of Aerodynamic Surfaces

In nature, gliding birds frequently execute intricate flight maneuvers such as aerial somersaults, perched landings, and swift descents, enabling them to navigate obstacles or hunt prey. It is evident that birds rely on different wing–tail configurations to accomplish a wide range of aerial maneuvers. For traditional fixed‐wing unmanned aerial vehicles (UAVs), pitch control primarily comes from the tail's elevators, while adjusting flight lift and drag involves deploying wing flaps. Although these designs ensure reliable flight, they compromise the drones’ maneuverability to maintain longitudinal stability. Therefore, the study introduces a biomimetic morphing wing UAV, and presents a pitch control strategy that simultaneously engages morphing wings, ailerons, and tail elevators. The pull‐up maneuver tests indicate that the proposed control method results in a pitch rate that is approximately 2.5 times greater than when using only the elevator control. A closed‐loop control system for the drone is also established. The closed‐loop flight experiment, which tracks a 45° pitch angle, demonstrates the effectiveness of the proposed coupled control method in adjusting the flight attitude. In addition, during cruising, the UAV employs three configurations, straight wing, forward‐swept wing, and back‐swept wing, to cater to different mission objectives and augment its flight capabilities.

A High-gain omnidirectional conformal antenna on the aerial vehicle

Abstract A series-fed conformal microstrip antenna with the tail wing of a UAV(Unmanned Aerial Vehicle)is proposed and implemented in this paper. In the target frequency band, the antenna has a nice performance of omnidirectional radiation and high gain, which easily conforms with the tail wing structure, achieving good wind resistance characteristics and meeting the strict aerodynamic requirements of the UAV. The antenna radiator is etched onto a printed board with a dielectric constant of 2.2 and a size of 644mm×112mm×4mm. In addition, the radiator is fixed with PMI form and formed a tail shape with surrounding glass fiber cloth, which has strong rigidity as a whole and has passed the flight test. The test results show that the antenna achieves a gain of more than 4.2 dBi at 564-676 MHz, a gain of more than 5.6 dBi at 600-650 MHz, and a gain of less than 3dB at 564-676MHz. This proposed antenna has a reasonable structure and good performance, which is verified by engineering experiments and is suitable for harsh environment requirements. It is expected that this antenna has wide applications in high-speed UAV communication.

Study on the Impact of Tail Wing Profiles on the Resistance Characteristics of Amphibious Vehicles

The resistance performance of amphibious vehicles can be improved by installing underwater tail hydrofoils. The research on the impact of different hydrofoil profiles on the resistance characteristics of amphibious vehicles can provide a reference for the vehicle’s design. For an amphibious vehicle model, five shapes of symmetrical hydrofoils, NACA0012, NACA0015, NACA0016, and asymmetric hydrofoils NACA23012, NACA66-209, were selected as the underwater tail wing of the vehicle body, respectively. Based on the RANS method and overset grid technology, the resistance performance of the vehicle body was numerically calculated, and the resistance variation in the amphibious vehicle equipped with different tail hydrofoils at 0.43 < Fr∇ < 1.3 speed was obtained. The basic shape of amphibious vehicle tail wings can be determined by comparing the effects of symmetrical hydrofoils and asymmetric hydrofoils on body resistance. The results show that the asymmetric hydrofoils have a better resistance reduction effect on amphibious vehicles than the symmetrical ones. Among them, an amphibious vehicle installing the asymmetric hydrofoil NACA66-209 as an underwater tail wing can reduce resistance by 44.3%. Chord length is an important factor affecting the resistance reduction performance of tail wings. When Fr∇ = 1.3, the asymmetric hydrofoil optimized based on chord length has a 21.2% higher resistance reduction effect on amphibious vehicles.

Development of a 2g butterfly-style flapping-wing micro aerial vehicle

A flapping-wing micro aerial vehicle (FMAV) modeled after a butterfly was developed to realize a palm-sized micro aerial vehicle capable of autonomous flight. It has a wingspan of about 220 mm, a weight of 1.8 g with the drive motor and battery installed, and flaps at a frequency of 7 Hz. The results of flight motion analysis using a high-speed camera showed that this butterfly-style FMAV, which does not rely on an external power source and does not have a tail wing, can fly in a straight line while maintaining a constant altitude with an initial speed given. We were also able to observe the flight trajectory of it, which moved up and down with a flapping motion similar to that of a real butterfly. The development of an FMAV that can fly like an insect is important for the viewpoint of robotics to elucidate the posture control mechanism of insects, which still needs to be clarified. The autonomous flight of this butterfly-style FMAV is significant in this regard.

Modeling and Hover Flight Control of a Micromechanical Flapping-Wing Aircraft Inspired by Wing–Tail Interaction

This article intends to give a comprehensive model to a brand new micromechanical flapping-wing aircraft inspired by wing–tail interaction. In this aircraft, the flapping-wing induced flow contributes to the tail control torque generation. However, this also makes the wing–tail interaction nonnegligible, and this flow would be disturbed by the relative flow produced by the body motion. The dominant unsteady aerodynamic effects of the flapping wing are considered. The flapping-wing induced flow over the tail is included when analyzing the tail aerodynamics. Especially, the aerodynamic–dynamic coupling effect of both the wing and the tail is considered to account for the force due to the body motion. A nonlinear and time-periodic simulation model of the aircraft is, thus, established. The model is averaged and linearized around hover status. Because of the combination of the wing–tail interaction with the aerodynamic–dynamic coupling, the state and control matrixes, including both the induced flow effect and the body motion effect, can be obtained. The pitch dynamics are analyzed, and it is found that the tail can push the two unstable oscillatory poles closer to the imaginary axis. The role of the tail is fully demonstrated by considering the induced flow. Cascade controllers are also designed according to the root-locus plot based on the built model. Due to the inclusion of the wing–tail interaction and the aerodynamic–dynamic coupling, the controllers are proved to be efficient in the attitude stabilization during statistic hover, descent, and ascent flights. Our proposed model can be easily applied to the modeling of other flapping-wing aircraft with similar structures, and it makes the controller design process more efficient and targeted.

Numerical study on the hydrodynamic lubrication performance improvement of bio-inspired peregrine falcon wing-shaped microtexture

Bio-inspired surface microtexture has been adopted in mechanical systems for its advanced lubrication performance. In this study, we discerned the aerodynamic characteristics of different parts of the peregrine falcon’s wing, summarized the influence of its distinctive shape on the fluid flow, and, based on simplified geometries and the bionic concept, designed a novel wing-shaped microtexture to enhance lubrication performance in friction pairs. Its shape was simplified by the following parameters: area ratio Sp, dimensionless depth h*, and orientation angle α. Using a multiphase flow model, we investigated the effect of the above geometrical parameters on the lubrication performance of the wing-shaped microtexture by numerical simulation. The corresponding geometrical parameters of the wing-shaped microtexture to achieve optimum lubrication performance were: Sp = 30%/h*=1.75/α = 0°. The wing-shaped microtexture’s friction coefficient(COF) corresponded to a reduction of 18.8% and 20.7%, respectively, compared to the triangle and rectangular microtexture, which had the best lubrication performance for existing applications. The results showed that the wing-shaped microtexture enhanced the lubrication performance for three reasons: 1. The biomimetic leading edge created more negative pressure and cavitation zones; 2. The interference between positive and negative pressure zones was effectively mitigated; 3. The sharp design of the biomimetic trailing edge and tail wing concentrated the positive pressure zone while increasing its area. Two double-layer composite wing-shaped microtextures were further introduced to maximize friction reduction. The impact of inner-outer layer area ratio Sp* and inner-outer depth ratio h* on the lubrication performance was investigated. Their simulation results revealed that the optimal geometric parameters for the composite microtextures were Sp*=6.3%/hp*=3.0 and Sp*=12.7%/hp*=2.0, respectively. The configurations led to additional COF reductions of 7.6% and 10.56% compared to the single-layer wing-shaped microtexture. These insights offer valuable guidance for reducing friction and wear in mechanical systems.

Design and Flight Performance of a Bio-Inspired Hover-Capable Flapping-Wing Micro Air Vehicle with Tail Wing

A key challenge in flapping-wing micro air vehicle (FWMAV) design is to generate high aerodynamic force/torque for improving the vehicle’s maneuverability. This paper presents a bio-inspired hover-capable flapping-wing micro air vehicle, named RoboFly.S, using a cross-tail wing to adjust attitude. We propose a novel flapping mechanism composed of a two-stage linkage mechanism, which has a large flapping angle and high reliability. Combined with the experimentally optimized wings, this flapping mechanism can generate more than 34 g of lift with a total wingspan of 16.5 cm, which is obviously superior to other FWMAVs of the same size. Aerodynamic force/torque measurement systems are used to observe and measure the flapping wing and aerodynamic data of the vehicle. RoboFly.S realizes attitude control utilizing the deflection of the cross-tail wing. Through the design and experiments with tail wing parameters, it is proved that this control method can generate a pitch torque of 2.2 N·mm and a roll torque of 3.55 N·mm with no loss of lift. Flight tests show that the endurance of RoboFly.S can reach more than 2.5 min without interferences. Moreover, the vehicle can carry a load of 3.4 g for flight, which demonstrates its ability to carry sensors for carrying out tasks.

An adaptive yaw method of horizontal-axis tidal stream turbines for bidirectional energy capture

Tracking the flow direction is one of the effective ways to harvest more energy for a horizontal-axis tidal stream turbine (HATST). This paper presents a novel HATST design that incorporates a yaw method with a tail wing, inspired by horizontal-axis wind turbines. The design enables the HATST to adaptively yaw toward the bidirectional flow with a reciprocating rotation. To ensure stability, a small yaw angle was reserved and permanent magnets were employed to hold the yaw mechanism steady. The kinetic equations of the yaw mechanism were established, and the influence of the yaw shaft's position and the tail wing's mass on the yaw performance was analyzed. A test model was constructed to validate the design and analysis, and the optimum parameters were discussed. Experimental results demonstrated that the HATST yawed well toward the inflow and maintained the designed yaw angle of approximately 5° at different velocities. Compared with the device without magnetic-assisted yaw, the HATST achieves more than 4.47% increase in output power in the velocity range of 0.15 m/s to 0.31 m/s, and exhibits minimal swing amplitude. This research provides a novel and practical solution for the effective utilization of bidirectional tidal steam energy.

Rocket-Inspired Effervescent Motors for Oral Macromolecule Delivery.

Oral administration is among the most convenient ways with good patient compliance for drug delivery; while it remains a challenge to achieve desirable bioavailability of most macromolecules due to the complex gastrointestinal barriers. Here, inspired by the structure and function of rocket, a novel micromotor delivery system is presented with scaled-down rocket-like architecture and effervescent-tablets-derived fuel for efficient oral macromolecule delivery by penetrating intestinal barrier. These rocket-inspired effervescent motors (RIEMs) are composed of sharp needle tips for both loading cargoes and efficient penetrating, and tail wings for loading effervescent powders and avoiding perforation. When exposed to a water environment, the effervescent fuel generates intensive CO2 bubbles to propel the RIEMs to move at high speed. Thus, the RIEMs with their sharp tip can inject into the surrounding mucosa for effective drug release. Furthermore, benefiting from their tail-wing design, perforation can be effectively avoided during the injection process, ensuring the safety of the RIEMs in gastrointestinal active delivery. Based on these advantages, it is demonstrated that the RIEMs can efficiently move and stab into the intestinal mucosa for insulin delivery, exhibiting efficacy in regulating blood sugar glucose in a diabetic rabbit model. These features indicate that these RIEMs are versatile and valuable for clinical oral delivery of macromolecules.

A Study on the Flight Safety Analysis of Military Aircraft External Stores

The external store fitted to the aircraft may affect the flight characteristics and flight safety of the aircraft, which requires the analyses and testing on it. The purpose of this study is to identify and analyze types of failures that can affect the flight safety of aircraft due to the installation of external stores, and to check the flight safety of aircraft through dropping tests of the external stores. After identifying the types of failures that could affect the flight safety of the aircraft, the criticality was calculated to analyze the effect on the flight safety of the aircraft. Four types of failures were selected: unintentional dropping, failure of dropping, unintentional main wing deployment, and release of tail wing restraint of the external store, which are considered to affect the flight safety of the aircraft due to the operation of the external store. As a result of the aircraft's flight safety analysis on the failure types, the criticality requirements were met. Based on this, after obtaining the airworthiness certification, the drop test was successfully performed to confirm the flight safety of the aircraft by mounting an external store on the aircraft. However, in addition to the four hazards carried out in this study, the real external stores of the military aircraft may have various factors affecting the flight safety of the aircraft, so further research will be needed.

A Study on the Flight Safety Analysis of Military Aircraft External Stores

The external store fitted to the aircraft may affect the flight characteristics and flight safety of the aircraft, which requires the analyses and testing on it. The purpose of this study is to identify and analyze types of failures that can affect the flight safety of aircraft due to the installation of external stores, and to check the flight safety of aircraft through dropping tests of the external stores. After identifying the types of failures that could affect the flight safety of the aircraft, the criticality was calculated to analyze the effect on the flight safety of the aircraft. Four types of failures were selected: unintentional dropping, failure of dropping, unintentional main wing deployment, and release of tail wing restraint of the external store, which are considered to affect the flight safety of the aircraft due to the operation of the external store. As a result of the aircraft's flight safety analysis on the failure types, the criticality requirements were met. Based on this, after obtaining the airworthiness certification, the drop test was successfully performed to confirm the flight safety of the aircraft by mounting an external store on the aircraft. However, in addition to the four hazards carried out in this study, the real external stores of the military aircraft may have various factors affecting the flight safety of the aircraft, so further research will be needed.

Inspection Interval Optimization for Aircraft Composite Tail Wing Structure Using Numerical-Analysis-Based Approach

Recently, there has been a tremendous increase in the use of fiber-reinforced composite (FRCP) in the aviation and aerospace industries due to its superior properties of high strength, stiffness, and low weight. The most important feature of implementing composite materials in aviation is their behavior under dynamic loads and resistance to fatigue. To predict the life of composite structures and optimize the inspection interval, it is essential to predict the damage behavior of composites. In this study, a model of fatigue delamination damage of composite specimens was first constructed using a finite element analysis (FEA)-based approach. The FEA modeling was verified through comparison with experimental specimen data, and the verified FEA model was applied to the composite material aircraft tail wing structure. In this case, a Monte Carlo simulation (MCS) was performed by building a response surface model while considering the uncertainty of the mechanical parameters. Through this process, the risk as a function of flight time could be quantitatively evaluated, and the inspection interval was optimized by selecting the combination with the lowest number of repeated inspections that met the permitted risk criteria.

Numerical study on flow characteristics of airfoil with bionic micro-grooves

Three airfoil models with bionic micro-grooves were developed to investigate the effect of the bionic micro-grooves on the airfoil flow field and aerodynamic performance. Large eddy simulation (LES) was used to predict the flow field around the airfoil. The Re were 1.6 × 105 and 2 × 105, and the angle of attack was 6°. The results show that all three airfoils reduce the velocity gradient at the airfoil suction surface near the wall and the energy loss in the boundary layer. The area of the recirculation zone of the H1 and H2 airfoils is significantly reduced. However, when the Re is 1.6 × 105, the area of the recirculation zone of the H3 airfoil increases. The aerodynamic performance of all three airfoils was improved. When the Re is 1.6 × 105, the aerodynamic performance of the H1 airfoil is improved most significantly, and the drag reduction rate reaches 16.41%. When the Re is 2 × 105, the aerodynamic performance improvement of H2 is the most obvious, and the drag reduction rate reaches 17.45%. In order to achieve the best drag reduction effect, the position of the bionic micro-grooves should gradually approach the wing's tail with the increase of Re.

결빙이 중형 수송기의 공력에 미치는 영향성에 관한 전산 해석

When the aircraft flies through rain or clouds, supercooled water droplets or cloud particles cause aircraft icing by impinging on the surface of the aircraft. Accreted ice causes a change in the shape of the wing, negatively affects aerodynamic characteristics, and is a direct threat to safe flight. In this study, the effect of icing on the aerodynamic performance of medium-sized transport aircraft was analyzed by computational simulation. The iced area attached to the leading edge of the main wing and the tail wing was observed to be up to 5.3 cm. In addition, the reduction in aerodynamic performance was more considerable in the glaze ice condition due to the complicated geometry of ice. As a result of the study, the effect of icing on the lift and drag coefficient was investigated. The lift coefficient decreased by approximately 20% and the drag coefficient increased by approximately 70%. This suggests that icing will have a negative effect on the cruising range and endurance, which are important performances of medium-sized transport aircraft. In the future, this study can be extended to studies on the effects of ice accretion and design of ice protection systems.

Aerodynamic thermal analysis of a spinning winged projectile

Aerodynamic heating of spinning flight vehicles have critical military applications such as flight testing, location tracking, stealth, and thermal protection. Based on the numerical method which is verified to be effective in the wind tunnel tests, this article discusses the aerodynamic thermal characteristics of a spinning winged projectile. Firstly, a 6-DOF trajectory model is established to demonstrate the motional behaviors. Partial flight data in supersonic, transonic, and subsonic regimes are separately defined as the inflow conditions. After that, thermo-fluid characteristics are compared between spin and non-spin. When the spin angular velocity is considered, a striking swirling flow phenomenon in the flow field, which result in the streamlines near the tail wings interfere with each other. Meanwhile, the impacts of the shear flow, trailing vortex and turbulent fluctuation are conspicuous. Besides, demonstrating the asymmetry of the temperature due to the flow deflection on the windward and leeward sides of the tail wings. Aerodynamic thermal differences on the surface of the tail wings are remarkable, especially at the tip of the wings. Therefore, the effects of spinning process on aerodynamic heating of winged vehicles cannot be ignored, particularly in supersonic flow at high Mach number.