Lehmann FO
J Exp Biol. 1998;201(3):385-401. doi: 10.1242/jeb.201.3.385.
By simultaneously measuring flight forces and stroke kinematics in several species of fruit flies in the genus Drosophila, we have investigated the relationship between wing motion and aerodynamic force production. We induced tethered flies to vary their production of total flight force by presenting them with a vertically oscillating visual background within a closed-loop flight arena. In response to the visual motion, flies modulated their flight force by changing the translational velocity of their wings, which they accomplished via changes in both stroke amplitude and stroke frequency. Changes in wing velocity could not, however, account for all the modulation in flight force, indicating that the mean force coefficient of the wings also increases with increasing force production. The mean force coefficients were always greater than those expected under steady-state conditions under a variety of assumptions, verifying that force production in Drosophila spp. must involve non-steady-state mechanisms. The subtle changes in kinematics and force production within individual flight sequences demonstrate that flies possess a flexible control system for flight maneuvers in which they can independently control the stroke amplitude, stroke frequency and force coefficient of their wings. By studying four different-sized species, we examined the effects of absolute body size on the production and control of aerodynamic forces. With decreasing body size, the mean angular wing velocity that is required to support the body weight increases. This change is due almost entirely to an increase in stroke frequency, whereas mean stroke amplitude was similar in all four species. Despite the elevated stroke frequency and angular wing velocity, the translational velocity of the wings in small flies decreases with the reduction in absolute wing length. To compensate for their small size, D. nikananu must use higher mean force coefficients than their larger relatives.
通过同时测量果蝇属几种果蝇的飞行力和冲程运动学，我们研究了翅膀运动与气动力产生之间的关系。我们在闭环飞行场地中向系留的果蝇呈现垂直振荡的视觉背景，诱导它们改变总飞行力的产生。作为对视觉运动的响应，果蝇通过改变翅膀的平移速度来调节其飞行力，这是通过改变冲程幅度和冲程频率来实现的。然而，翅膀速度的变化并不能解释飞行力的所有调节，这表明翅膀的平均力系数也随着力产生的增加而增加。在各种假设下，平均力系数总是大于稳态条件下预期的值，这证实了果蝇属的力产生必须涉及非稳态机制。单个飞行序列中运动学和力产生的细微变化表明，果蝇拥有一个灵活的飞行操纵控制系统，在这个系统中，它们可以独立控制翅膀的冲程幅度、冲程频率和力系数。通过研究四种不同大小的物种，我们研究了绝对体型对气动力产生和控制的影响。随着体型减小，支撑体重所需的翅膀平均角速度增加。这种变化几乎完全是由于冲程频率的增加，而所有四个物种的平均冲程幅度相似。尽管冲程频率和翅膀角速度升高，但小果蝇翅膀的平移速度随着绝对翅膀长度的减小而降低。为了弥补其体型小的不足，尼卡纳努果蝇必须比其体型较大的亲属使用更高的平均力系数。
