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  2. INTRODUCTION • Humans are always anxious in discovering the secrets of living nature and towards conceiving new ideas and developing entirely new technologies. • The idea of utilizing the thrust generated by flapping wings for the propulsion of man-made objects emerged from observations of fish and birds. • In 1490 Leonardo da Vinci first made an attempt to explain and implement the mechanism of thrust generation by a flapping wing.

  3. In the 1960s a separate research field was initiated named bionics , which includes studies of the principles of flapping-wing propulsion. • Among the many existing propulsors the flapping-wing propulsion systems occupy a special place because so many living species have evolved them.

  4. OBJECTIVES • To review the performance of flapping wings . • Discuss the relevance of flapping wings in present scenario. • To discuss the various applications of flapping wings.

  5. WHY FLAPPER WINGS • Can be viewed as ‘‘ecologically’’ pure • Are relatively low-frequency systems • Possess sufficiently high efficiency • Is more effective for specific power requirment in low speed application • Can combine the function of propulsor, control device, and stabilizer,can provide static thrust

  6. PERFORMANCE EVALUATION • Fish, insects, warm-blooded vertebrates, and cetaceans who all use some oscillating wing mechanism for thrust generation. • coefficient of aerohydrodynamic perfection K=NL/MU • The greatest hydrodynamic perfection is achieved by dolphins, whereas the largest relative speeds are reached by birds and insects • There are two classes of aerial flapping flight—birdlike and insect-like.

  7. INSECTS • Typical flapping frequencies are in the range of 5–200 Hz. • The motion of the flapping wing itself can be divided broadly into translational and rotational phases. • The translational phase consists of two half-strokes—the downstroke and the upstroke • At either ends of the half-strokes, the rotational phases come into play

  8. The leading-edge vortex starts close to the wing root and spirals towards the tip where it coalesces with the tip vortex • As the translational motion gets underway, one of the previous LEVs joins the starting vortex at the trailing edge • Large magnitudes of the lift coefficients, realized by insects is due to the formation of leading edge vortices, which interact with vorticity shed from the trailing edge.

  9. In short insect flight can be concluded as • specific kinematics of the wing motion, • favorable vortex interactions between the leading and trailing edge vortices causing high propulsive and lift properties • ability to use several flight modes • vertical take-off capability, • ability of ‘‘hanging’’ in the air

  10. MICRO AIR VEHICLE • vehicles with dimensions less than 6 in • speed of flight of 30–60 km/h and duration of flight up to 60 min. • Some of the MAVs are • ‘‘Micro Bat’’ (Aerovironment/California Institute of Technology, Pasadena, CA). • An Elasto-Dynamic Ornithopic Flying Robotic Insect (Vanderbilt Univeristy, Nashville, TN). • Robo fly

  11. Full-size Ornithopters • large vehicles, which have flapping wings for lifting and propulsion purposes. • ornithopters emerged long ago as an attempt by man to create a ‘‘bird-like’’ flying machine. • Ornithopers may be human powered and engine powered.

  12. In 1929, a man-powered ornithopter designed by Alexander Lippisch flew a distance of 250 to 300 metres • In 1942, AdalbertSchmid made a much longer flight of a human-powered ornithopter at Munich-Laim. It travelled a distance of 900 metres, maintaining a height of 20 metres throughout most of the flight • A team at the University of Toronto Institute for Aerospace Studies, headed by ProfessorJames DeLaurier, worked for several years on an engine-powered, piloted ornithopter.

  13. CONCLUSION • Flapping wings are more effective in the case of specific power requirement in low speed. • MAVs are gaining it acceptance world wide and many countries like USA,RUSSIA etc project it as its future weapon. • As of today ornithopers of 60 kg carrying capacity is designed. • Blind copying of the ‘‘mechanisms’’of living species may not lead to positive results.

  14. REFERENCES • Aerodynamic modelling of insect-like flapping flight for micro air vehicles S.A. Ansari, R. Z˙ bikowski, K. Knowles • Aerohydrodynamics of flapping-wing propulsors Kirill V. Rozhdestvensky*, Vladimir A. Ryzhov • Lavrentiev MA, Shabat MV. Problems of hydromechanics and their mathematical models. Moscow: Nauka;1973. p. 302–9.


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