Fig. 13. Smoke visualizations stepping across the thorax of Aeshna grandis in tethered flight. The flow pattern, shape, size and structure of the LEV is consistent at all positions across the thorax, and from wingbeat to wingbeat. (A–L) Oblique front views in which the dragonfly is traversed through the smoke plane in 1 mm steps from the far wing hinge across the thorax and out onto the near wing. There is a leading edge vortex in all images, and the shape and size of the LEV is consistent across the thorax and out onto the wing. (I-VI) Higher resolution side images. The dragonfly is traversed through the smoke plane in 2 mm steps so that the smoke impinges on the far side of the thorax in I, is on the midline and hits the dragonfly between the eyes in IV, and is out on the near wing base in VI. The blue arrows show the stagnation point where the separatrix touches down on the top of the thorax or hindwing. The shape and size of the leading edge vortex are strikingly consistent, even though the wing chord and velocity change dramatically as we step along the wing, across the narrow wing base onto the thorax. This is a remarkable result, suggesting that while the wings form the LEV the details of their shape, size and motion are not amongst the principle parameters controlling LEV morphology.