Artificial Muscle Research Center, Konkuk University, Seoul, Republic of Korea. Department of Smart Vehicle Engineering, Konkuk University, Seoul, Republic of Korea.
Bioinspir Biomim. 2019 Sep 13;14(6):066006. doi: 10.1088/1748-3190/ab3d55.
Beetle Allomyrina dichotoma is one of the largest insects that performs many remarkable modes of locomotion, particularly hovering flight capability. In order to stay airborne, its flexible hindwings are flapped so as to work as a thrust generator. However, the wing loading of the beetle is relatively large (38.94 ± 3.73 N m) compared to those of other insects and hummingbirds, indicating that it is challenging for it to achieve flight. Here, we measured the hindwing morphology and kinematics of the beetle in order to discover its flight performance. Unlike many other insects, the beetle flaps its hindwings with an extremely large sweep amplitude of about 191.33 ± 6.12 deg at high flapping frequencies ranging from 36 to 41 Hz (mean wing tip speed ≈ 13.45 ± 0.58 m s). These capabilities enable the beetle to produce enough lift force to stay airborne with its bulky body (4-10 g). In order to investigate how the sweep amplitude affects the beetle's flight efficiency, we utilized the unsteady blade element model to estimate the power requirements of the same vertical force production for various sweep amplitudes. The results indicate that the sweep amplitude as high as 190 deg is more beneficial for power requirements than the smaller amplitudes, which require higher frequencies resulting in higher inertial powers to produce the same vertical force. Thus, for this large beetle, high sweep amplitude may be a biological strategy for staying airborne. In addition, we thoroughly discussed the effects of input constraints on the outcome by investigating power loadings for variable sweep amplitudes at a constant vertical force, mean wing tip speed, and flapping frequency. Effect of wing surface area was also investigated and discussed to provide useful information for the development of an insect-inspired flapping-wing robot.
锹甲 Allomyrina dichotoma 是能够做出多种奇特移动方式的最大昆虫之一，尤其擅长悬停飞行。为了在空中停留，锹甲的后翅灵活地拍打，充当推力发生器。然而，与其他昆虫和蜂鸟相比，其翅膀的单位负载相对较大（38.94±3.73 N m），这表明其飞行具有挑战性。在这里，我们测量了甲虫的后翅形态和运动学，以发现其飞行性能。与许多其他昆虫不同，甲虫以高达 191.33±6.12 度的超大幅摆幅拍打后翅，在 36 至 41 Hz 的高拍打频率范围内（平均翼尖速度约为 13.45±0.58 m s）。这些能力使甲虫能够产生足够的升力，使体型庞大的身体在空中停留（4-10 g）。为了研究摆幅如何影响甲虫的飞行效率，我们利用非定常翼段模型来估计不同摆幅下产生相同垂直力所需的功率需求。结果表明，高达 190 度的摆幅比较小的摆幅更有利于降低功率需求，因为较小的摆幅需要更高的频率来产生相同的垂直力，从而导致更高的惯性功率。因此，对于这种大型甲虫来说，高摆幅可能是在空中停留的一种生物策略。此外，我们通过研究在恒定垂直力、平均翼尖速度和拍打频率下可变摆幅的功率负载，彻底讨论了输入约束对结果的影响。我们还研究和讨论了翼面积的影响，以为昆虫启发的扑翼机器人的开发提供有用信息。
