School of Mechanical Engineering, Purdue University, Zucrow Laboratories, West Lafayette, IN 47907, USA.
J Exp Biol. 2010 Feb 15;213(4):602-12. doi: 10.1242/jeb.038778.
We systematically investigated the effect of body rotation on the aerodynamic torque generation on flapping wings during fast turning maneuvers (body saccades) in the fruit fly Drosophila. A quasi-steady aerodynamic simulation of turning maneuvers with symmetrically flapping wings showed that body rotation causes a substantial aerodynamic counter-torque, known as flapping counter-torque (FCT), which acts in the opposite direction to turning. Simulation results further indicate that FCTs are linearly dependent on the rotational velocity and the flapping frequency regardless of the kinematics of wing motion. We estimated the damping coefficients for the principal rotation axes - roll, pitch, yaw - in the stroke plane frame. FCT-induced passive damping exists about all the rotation axes examined, suggesting that the effects of body rotation cannot be ignored in the analysis of free-flight dynamics. Force measurements on a dynamically scaled robotic wing undergoing realistic saccade kinematics showed that although passive aerodynamic damping due to FCT can account for a large part of the deceleration during saccades, active yaw torque from asymmetric wing motion is required to terminate body rotation. In addition, we calculated the mean value of the damping coefficient at 21.00 x10(-12) N m s based on free-flight data of saccades, which is somewhat lower than that estimated by the simulation results (26.84 x 10(-12) N m s).
我们系统地研究了在果蝇的快速转弯（身体扫视）机动中，身体旋转对扑翼产生的空气动力扭矩的影响。带有对称扑翼的转弯机动的准稳态空气动力模拟表明，身体旋转导致了相当大的空气动力反向扭矩，称为扑翼反向扭矩（FCT），其作用方向与转弯相反。模拟结果还表明，无论机翼运动的运动学如何，FCT 都与旋转速度和扑翼频率呈线性相关。我们估计了在冲程平面框架中主要旋转轴（滚转、俯仰、偏航）的阻尼系数。在检查的所有旋转轴上都存在 FCT 引起的被动阻尼，这表明在分析自由飞行动力学时，不能忽略身体旋转的影响。在经历真实扫视运动学的动态缩放机器人机翼上进行的力测量表明，尽管由于 FCT 引起的被动空气动力阻尼可以解释扫视过程中的大部分减速，但需要来自不对称机翼运动的主动偏航扭矩来终止身体旋转。此外，我们根据扫视的自由飞行数据计算了阻尼系数的平均值为 21.00 x10(-12) N m s，略低于模拟结果（26.84 x 10(-12) N m s）估计的值。
