Can scalable design of wings for flapping wing micro air vehicle be inspired by natural flyers?

Lift production is constantly a great challenge for flapping wing micro air vehicles (MAVs). Designing a workable wing, therefore, plays an essential role. Dimensional analysis is an effective and valuable tool in studying the biomechanics of flyers. In this paper, geometric similarity study is firstly presented. Then, the pw−AR ratio is defined and employed in wing performance estimation before the lumped parameter is induced and utilized in wing design. Comprehensive scaling laws on relation of wing performances for natural flyers are next investigated and developed via statistical analysis before being utilized to examine the wing design. Through geometric similarity study and statistical analysis, the results show that the aspect ratio and lumped parameter are independent on mass, and the lumped parameter is inversely proportional to the aspect ratio. The lumped parameters and aspect ratio of flapping wing MAVs correspond to the range of wing performances of natural flyers. Also, the wing performances of existing flapping wing MAVs are examined and follow the scaling laws. Last, the manufactured wings of the flapping wing MAVs are summarized. Our results will, therefore, provide a simple but powerful guideline for biologists and engineers who study the morphology of natural flyers and design flapping wing MAVs

Structural Analysis of a Dragonfly Wing

Dragonfly wings are highly corrugated, which increases the stiffness and strength of the wing significantly, and results in a lightweight structure with good aerodynamic performance. How insect wings carry aerodynamic and inertial loads, and how the resonant frequency of the flapping wings is tuned for carrying these loads, is however not fully understood. To study this we made a three-dimensional scan of a dragonfly (Sympetrum vulgatum) fore- and hindwing with a micro-CT scanner. The scans contain the complete venation pattern including thickness variations throughout both wings. We subsequently approximated the forewing architecture with an efficient three-dimensional beam and shell model. We then determined the wing’s natural vibration modes and the wing deformation resulting from analytical estimates of 8 load cases containing aerodynamic and inertial loads (using the finite element solver Abaqus). Based on our computations we find that the inertial loads are 1.5 to 3 times higher than aerodynamic pressure loads. We further find that wing deformation is smaller during the downstroke than during the upstroke, due to structural asymmetry. The natural vibration mode analysis revealed that the structural natural frequency of a dragonfly wing in vacuum is 154 Hz, which is approximately 4.8 times higher than the natural flapping frequency of dragonflies in hovering flight (32.3 Hz). This insight in the structural properties of dragonfly wings could inspire the design of more effective wings for insect-sized flapping micro air vehicles: The passive shape of aeroelastically tailored wings inspired by dragonflies can in principle be designed more precisely compared to sail like wings —which can make the dragonfly-like wings more aerodynamically effective

Analysis and experiment of a bio-inspired flyable micro flapping wing rotor

Inspired by insect flapping wings, a novel flapping wing rotor (FWR) has been developed for micro aerial vehicle (MAV) application. The FWR combines flapping with rotary kinematics of motions to achieve high agility and efficiency of flight. To demonstrate the feasibility of FWR flight and its potential MAV application, an extensive and comprehensive study has been performed. The study includes design, analysis, manufacture, experimental and flight test of a flyable micro FWR model of only 2.6 gm weight. By experiment, the FWR kinematic motion and aerodynamic lift were measured using high speed camera and load cells. Within a range of input power, the difference between the measured aerodynamic force and the analytical results by a quasi-steady model was found to be within 3.1%–15.7%. It is noted that the FWR aeroelastic effect plays a significant role to obtain an ideal large angle of attack especially in up-stroke and enhance the FWR performance. Further analysis of the unsteady aerodynamic characteristics has been carried out based on the detailed airflow field of the FWR in a flapping cycle by CFD method. A successful vertical take-off and short hovering flight of the micro FWR model has been achieved for the first time in the research field. The flight test demonstrates the FWR feasibility and its unique feature of flight dynamics and stability for the first time. These characteristics have also been simulated by using ADAMS software interfaced with the aerodynamic model

DESIGN, ANALYSIS, AND TESTING OF A FLAPPING WING MINIATURE AIR VEHICLE

Flapping wing miniature air vehicles (MAVs) offer several advantageous performance benefits, relative to fixed-wing and rotary-wing MAVs. The goal of this thesis is to design a flapping wing MAV that achieves improved performance by focusing on the flapping mechanism and the spar arrangement in the wings. Two variations of the flapping mechanism are designed and tested, both using compliance as a technique for improved functionality. In the design of these mechanisms, kinematics and dynamics simulation is used to evaluate how forces encountered during wing flapping affect the mechanism. Finite element analysis is used to evaluate the stress and deformation of the mechanism, such that a lightweight yet functional design can be realized. The wings are tested using experimental techniques. These techniques include high speed photography, stiffness measurement, and lift and thrust measurements. Experimentally measured force results are validated with a series of flight tests. A framework for iterative improvement of the MAV is described, that uses the results of physical testing and simulations to investigate the underlying causes of MAV performance aspects; and seeks to capture those beneficial aspects that will allow for performance improvements. Wings and flapping mechanisms designed in this thesis are used to realize a bird-inspired flapping wing miniature air vehicle. This vehicle is capable of radio controlled flights indoors and outdoors in winds up to 6.7m/s with controlled steering, ascent, and descent, as well as payload carrying abilities

Development of Tailless Flapping Wing System With 2.4 GHz Wireless Communication

Recently, there have been studies on characteristics of flapping motion of small birds and insects in flight where in that size category; flapping wing designs excel over their fixed wing counterparts. Despite that, complexities of wing motion and biomechanism of birds and insects added many difficulties to build an efficient flapping mechanism, especially that without tail configuration. In an attempt to overcome such difficulties, two motor-driven flapping wing system micro aerial vehicles (FW-MAV) were developed without tail configuration. First FW-MAV has one DC motor to drive its wing motion and optionally magnetic actuator for maneuverability. The second FW-MAV has two DC motors that can separately generate flapping wing motion. In addition, 2.4 GHz wireless communication was also implemented to both FW-MAV to remotely control the wing actuators. Then to evaluate their flight efficiency, flapping motion of the two FW-MAVs were evaluated based on kinematics simulation and flapping frequency test measurement. Further, thrusts produced by both FW-MAVs were also measured and compared. Based on the measurement, FW-MAV with two motors was about 4% heavier than the other FW-MAV, but it can generate about 10% larger flapping angle and about 3 times of thrust

Development of Tailless Flapping Wing System With 2.4 GHz Wireless Communication

Sekarang ini, telah banyak studi tentang karakteristik terbang burung kecil dan serangga di mana di dalam kategori ukuran ini, desain flapping wing (kepakan sayap) unggul atas desain fixed-wing. Meskipun demikian, kompleksitas gerakan dan biomekanisme sayap burung dan serangga memperbanyak kesulitan dalam pembuatan sistem kepakan yang efisien, terutama yang tidak memiliki konfigurasi ekor. Dalam upaya untuk mengatasi kesulitan tersebut, dikembangkan dua sistem kepakan sayap (FW-MAV) tanpa konfigurasi ekor. FW-MAV yang pertama hanya memiliki satu motor untuk menggerakkan sayap dan dapat ditambahkan sebuah magnetic actuator untuk menambah kemampuan manuvernya. Sedangkan yang kedua memiliki dua motor yang secara terpisah dapat mengepakkan dua sayap. Sarana komunikasi nirkabel 2,4 GHz juga ditambahkan untuk mengontrol jarak jauh kedua sistem FW-MAV. Kemudian, tingkat efisiensi terbang kedua FW-MAV diukur berdasarkan simulasi kinematika dan frekuensi kepakan. Selanjutnya, gaya dorong yang dihasilkan oleh kedua FW-MAV juga diukur dan dibandingkan. Berdasarkan pengukuran tersebut, FW-MAV dengan dua motor memiliki berat 4% lebih besar dari model dengan satu motor, tetapi dapat menghasilkan sudut kepakan 10% lebih besar dan 3 kali lipat gaya dorong

Unsteady aerodynamic and optimal kinematic analysis of a micro flapping wing rotor

Inspired by the high performance of rotary and insect flapping wings capable of vertical take-off and landing and hovering (VTOLH), a novel flapping wing rotor (FWR) has been developed by combining the above two types of wing motions. The FWR offers an alternative configuration for micro air vehicles (MAV) of such high flight performance. Unlike the well-studied aerodynamics of rotary and insect-like flapping wing with prescribed wing motion, the aerodynamic lift and efficiency of the FWR associated with optimal kinematics of motion has not been studied in a systematic manner before. This investigation is therefore focused on the FWR optimal kinematic motion in terms of aerodynamic lift and efficiency. Aerodynamic analysis is conducted for a FWR model of aspect ratio 3.6 and wing span 200 mm in a range of kinematic parameters. The analysis is based on a quasi-steady aerodynamic model with empirical coefficients and validated by CFD results at Re∼3500. For comparison purpose, the analysis includes rotary and insect-like flapping wings in hovering status with the FWR at an equilibrium rotation speed when the thrust equals to drag. The results show that the rotary wing has the greatest power efficiency but the smallest lift coefficient. Whereas the FWR can produce the greatest aerodynamic lift with power efficiency between rotary and insect-like flapping wings. The results provide a quantified guidance for design option of the three types of high performance MAVs together with the optimal kinematics of motion according to flight performance requirement