[推荐]Dragonfly Flight II(蜻蜓飞行的运动学)

yjs808

DRAGONFLY FLIGHT
II. VELOCITIES, ACCELERATIONS AND KINEMATICS OF FLAPPING FLIGHT
J. M. WAKELING  AND C. P. ELLINGTON
Summary:
The free flapping flight of the dragonfly Sympetrum sanguineum and the damselfly Calopteryx splendens was filmed in a large flight enclosure at 3000 frames s-1. The wingtip kinematics are described for these flights. Despite
the two species being similar in size, the damselfly flew with wingbeat frequencies half those of the dragonfly. The damselfly could perform a clap and fling, and the proximity to which the wings approached each other during this
manoeuvre correlated with the total force produced during the wingstroke. The dragonfly beat its wings with a set inclination of the stroke planes with respect to the londitudinal body axis; the damselfly, in contrast, showed
a greater variation in this angle. Both species aligned their stroke planes to be nearly normal to the direction of the resultant force, the thrust. In order to achieve this, the dragonfly body alignment correlated with the direction of
thrust. However, the damselfly body alignment was independent of the thrust direction. Velocities and accelerations were greater for the dragonfly than for the damselfly. However, non-dimensional velocities and accelerations normalised by the wingbeat periods were  greater for the damselfly.