Institute of Fluid Mechanics, Beijing University of Aeronautics & Astronautics, Beijing, People's Republic of China.
Bioinspir Biomim. 2018 Jul 31;13(5):056008. doi: 10.1088/1748-3190/aad212.
We measured the wing kinematics of fruitflies in both vertically-ascending and hovering flights and studied the aerodynamic forces and power in the two flight modes. The average ascending velocity is 0.45 m s; the stroke plane angle and the stroke frequency are the same as that in hovering flight, whilst the stroke amplitude is increased by 12% and the wing angle of attack in the latter half of a down- and upstroke both increased by 10%. Flow analysis shows that during ascending, the flies experience a downward inflow which reduces the effective angle of attack considerably. This problem is overcome by the increases in the stroke amplitude and the angle of attack, which result in a larger wing drag. As a result, the power at ascending is increased by 36% over that at hovering. Two very interesting observations were made. (1) Using the same power, level-forward flight can be about four times as fast as ascending flight. (2) Power for ascending flight is the same as that for carrying a load about 27% of the insect's weight at hovering.
我们测量了果蝇在垂直上升和悬停飞行中的翅膀运动学，并研究了两种飞行模式下的空气动力和功率。平均上升速度为 0.45 米/秒；拍动平面角和拍动频率与悬停飞行相同，而拍动幅度增加了 12%，后半段的翼攻角在上下拍动时都增加了 10%。流场分析表明，在上升过程中，苍蝇经历了向下的流入，这大大降低了有效攻角。通过增加拍动幅度和攻角，这个问题得到了解决，这导致了更大的机翼阻力。因此，上升时的功率比悬停时增加了 36%。有两个非常有趣的观察结果。（1）使用相同的功率，水平向前飞行的速度大约是上升飞行的四倍。（2）上升飞行的功率与悬停时携带约 27%昆虫体重的负载的功率相同。
