Alexander D E
J Exp Biol. 1986 May;122:81-98. doi: 10.1242/jeb.122.1.81.
High-speed movies of dragonflies turning in flight on flexible tethers show that there are two distinct modes of turning. In the 'conventional' mode, dragonflies use left-right asymmetries in the wing stroke amplitude, and occasionally in the angle of attack, to produce more lift and thrust on one side than the other. This causes the animal to roll into a bank, so that the lift vector has a sideward component; this sideward component produces the turn, much as in an airplane. This type of turn is probably most useful during fast forward flight. The second mode of turning in the 'yaw turn'. Yaw turns are accomplished without banking, and the dragonfly's long axis may turn more than 90 degrees in the period of two wing strokes. The kinematics of this turn could not be as closely analysed, but it appears that dragonflies use drag on the inner wing upstroke and the outer wing downstroke to turn, much like pivoting a rowing boat. This turn may be hampered by drag on the abdomen during fast forward flight and would be most useful at low speeds or during hovering.
对在柔性系绳上飞行转弯的蜻蜓进行的高速拍摄显示，蜻蜓有两种不同的转弯模式。在“常规”模式下，蜻蜓利用翅膀冲程幅度的左右不对称，偶尔也利用攻角的不对称，在一侧产生比另一侧更多的升力和推力。这会使动物翻滚成倾斜状态，从而使升力矢量具有侧向分量；这个侧向分量产生转弯，就像在飞机上一样。这种转弯类型可能在快速向前飞行时最有用。第二种转弯模式是“偏航转弯”。偏航转弯是在不倾斜的情况下完成的，并且蜻蜓的长轴在两个翅膀冲程的时间内可能转过超过90度。这种转弯的运动学无法进行如此细致的分析，但似乎蜻蜓利用内翼向上冲程和外翼向下冲程时的阻力来转弯，很像转动划艇。在快速向前飞行时，腹部的阻力可能会妨碍这种转弯，而它在低速或悬停时可能最有用。
