Encyclopedia of Aerospace Engineering, Online © 2010 John Wiley & Sons, Ltd. This article is © 2010 John Wiley & Sons, Ltd. This article was published in the Encyclopedia of Aerospace Engineering in 2010 by John Wiley & Sons, Ltd. MAV-Motivated Structures and Materials Kwang-Joon Yoon, Joon-Hyuk Park, and Sriyulianti Widhiarini Konkuk University, Seoul, Korea 1 Introduction 1 2 Flapping-wing MAV Development 1 3 Design and Manufacture of Biomimetic Flapping-wing MAV 4 4 Performance Test and Evaluation 8 5 Summary 11 Acknowledgments 11 References 11 1 INTRODUCTION Nature’s flyers, such as birds, bats, and insects have amazed humankind for long with their remarkable flight charac- teristics, which triggered the development of manmade air vehicles. The study of flight can be traced back to the earliest design of the manmade flying machine, by Leonardo da Vinci in 1500s in the form a of flapping vehicle. However, the devel- opment drifted ever since the successful powered flight using fixed-wings by Wright brothers. More remarkable innova- tions later followed this success, and they were all focused on fixed wing aircraft. Recently, active air vehicle research, inspired by nature’s flyers, has led to the development of micro air vehicles (MAVs). It is now a well-integrated research area in the devel- opment of smaller flight vehicles for environmental monitor- ing, surveillance, and assessments in hostile environments. As the sizes of the MAVs are getting smaller, they have been developed to mimic nature as closely as possible. They are expected to have high maneuverability and very low speed ca- pability, but at the same time, should be able to reach those ca- pabilities with high power and high aerodynamic efficiency in a low Reynolds number environment, from 50 000 to 150 000. Consequently, MAVs will experience increasing drag and loss of efficiency due to the low Reynolds number. Due to the limitations of size, their wings also have a small aspect ratio which will reduce the effective angle of attack and induce the 3D flow structure created when they fly. Moreover, they are also sensitive to wind gusts, and become more difficult to control. MAVs can be generally categorized into three kinds based on their mechanism of producing lift: fixed, rotary, and flapping-wing. Research on fixed-wing MAV is the most de- veloped area among other categories. The second category of MAV is rotary-wing. Compared to the earlier type, this MAV has a relatively lower endurance due to its smallscale rotors causing highly effective power requirements for the hover. Next is the flapping-wing MAV, its research comes from the inspiration of mimicking the mechanism and features of birds and insects. The aerodynamics of this vehicle is highly unsteady due to acceleration and deceleration of the wing dur- ing its up and down movements, in addition to the highly rela- tive viscous effect at low Reynolds number that already exists. 2 FLAPPING-WING MAV DEVELOPMENT 2.1 Overview MAVs with a 15 cm wingspan seem to have the characteristics between the borders of two groups of nature’s flyers because DOI: 10.1002/9780470686652.eae405