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首页> 外文期刊>The Journal of Experimental Biology >Kinematics of flap-bounding flight in the zebra finch over a wide range of speeds
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Kinematics of flap-bounding flight in the zebra finch over a wide range of speeds

机译：斑马雀在各种速度下的襟翼包围飞行运动学

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It has been proposed elsewhere that flap-bounding, an intermittent flight style consisting of flapping phases interspersed with flexed-wing bounds, should offer no savings in average mechanical power relative to continuous flapping unless a bird flies 1.2 times faster than its maximum range speed (V_(mr)). Why do some species use intermittent hounds at speeds slower than 1.2V_(mr)? The 'fixed-gear hypothesis' suggests that flap-bounding is used to vary mean power output in small birds that are otherwise constrained by muscle physiology and wing anatomy to use a fixed muscle shdrtening velocity and pattern of wing motion at all flight speeds: the 'body-lift hypothesis' suggests that some weight support during bounds could make flap-bounding flight aerodynamically advantageous in comparison with continuous flapping over most forward flight speeds. To test these predictions, we studied high-speed film recordings (300Hz) of wing and body motion in zebra finches (Taenopygia guttata, mean mass 13.2 g, N=4) taken as the birds flew in a variable-speed wind tunnel C0-14ms~(-1)). The zebra finches used flapbounding flight at all speeds, so their flight style was uniqne compared with that of birds that facultatively shift from continuous flapping or flap-gliding at slow speeds to flapbounding at fast speeds. There was a significant effect of flight speed on all measured aspects of wing motion except percentage of the wingbeat spent in downstroke. Changes in angular velocity of the wing indicated that conlractile velocity in the pectoralis muscle changed with flight speed, which is not consistent with the fixed-gear hypothesis. Although variation in stroke-plane angle relative to the body, pronation angle of the wing and wing span at midupstroke shuwed that the zebra finch changed withinwingbeat geometries according to speed, a vortex-ring gait with a feathered upstroke appeared to be the only gait used during flapping. In contrast, two small species that use continuous flapping during slow flight (0-4ms~(-1)) either change wingbeat gait according to flight speed or exhibit more variation in stroke-plane and pronation angles relative to the body. Differences in kinematics among species appear to be related to wing design (aspect ratio, skeletal proportions} rather than to pectoralis muscle fiber composition, indicating that the fixed-gear hypothesis should perhaps be modified to exclude muscle physiology and to emphasize constraints due to wing anatomy. Body lilt was prnduced during bounds at speeds from 4 to 14ms~(-1). Maximum body lift was 0.0206N (15.9 % of body weight) at 10ms~(-1); body lift:drag ratio declined with increasing air speed. The aerodynamic function of bounds differed with increasing speed from an emphasis on lift production (4-10ms~(-1) to an emphasis on drag reduction with a slight loss in lift (12 and 14ms~(-1)). From a mathematical model of aerodynamic costs, it appeared that flap-bounding offered the zebra finch an aerodynamic advantage relative to continuous flapping at moderate and fast flight speeds (6-14ms~(-1)), with body lift augmenting any savings offered solely by flap-bounding at speeds faster than 7.1ms~(-1). The percentage of time spent flapping during an intermittent flight cycle decreased with increasing speed, so the mechanical cost of transport was likely to be lowest at faster flight speeds (10-14ms~(-1)).
机译：在其他地方已经提出，襟翼包围是一种间歇性的飞行样式，由扑翼阶段和挠性机翼边界点缀组成，相对于连续扑翼，平均机械功率没有任何节省，除非鸟类飞出的速度比其最大射程速度快1.2倍（ V_（mr））。为什么某些物种使用间歇性猎犬以低于1.2V_（mr）的速度？ ``固定齿轮假说''表明，襟翼定界用于改变小鸟的平均功率输出，否则它们会受到肌肉生理和机翼解剖的约束，以在所有飞行速度下使用固定的肌肉收缩速度和机翼运动模式： “举升假说”表明，在大多数向前飞行速度上，与连续扑翼相比，在边界期间一定的重量支撑可使使襟翼越界的飞行在空气动力学上更具优势。为了检验这些预测，我们研究了鸟类在变速风洞C0-中飞翔时在斑马雀（Taenopygia guttata，平均质量13.2 g，N = 4）中机翼和身体运动的高速胶片记录（300Hz）。 14ms〜（-1））。斑马雀在所有速度下都使用扑翼飞行，因此它们的飞行方式与那些从低速连续拍打或襟翼滑行过渡到快速扑翼的鸟类相比具有独特的飞行风格。飞行速度对机翼运动的所有测量方面都有显着影响，除了在下击中花费的机翼节拍百分比。机翼角速度的变化表明胸大肌中的交感速度随飞行速度而变化，这与固定齿轮假说不符。尽管笔划平面角相对于身体的变化，机翼的中转角和机翼在中风时的跨度都使斑马雀科根据速度改变了机翼的几何形状，但似乎仅有羽毛步态的涡环步态是使用的步态在拍打期间。相比之下，两个在慢速飞行（0-4ms〜（-1））中使用连续拍打的小物种要么根据飞行速度改变机翼步态，要么相对于身体表现出更大的冲程平面和旋前角变化。物种之间的运动学差异似乎与机翼设计有关（长宽比，骨骼比例），而不是与胸大肌的肌纤维成分有关，这表明应该修改固定齿轮的假说以排除肌肉生理并强调由于机翼解剖结构引起的限制。在4到14ms〜（-1）的速度范围内进行身体倾斜动作，在10ms〜（-1）的最大身体升力为0.0206N（占体重的15.9％）;随着空气速度的增加，身体升力：阻力比下降。 。边界的空气动力学功能随着速度的增加而有所不同，从强调升力产生（4-10ms〜（-1）到注重减阻和升力略有下降（12和14ms〜（-1））有所不同。空气动力学成本的数学模型似乎表明，相对于在中等和较快的飞行速度（6-14ms〜（-1））连续拍打，襟翼定界为斑马雀提供了空气动力学优势，而车身升力增加了仅由襟翼提供的任何节省以更快的速度7.1ms〜（-1）随着速度的增加，在间歇性飞行周期中扑动所花费的时间百分比降低，因此，在较快的飞行速度（10-14ms〜（-1））下，机械的运输成本可能最低。

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