On the attitude stability of flying dandelion seeds

Dandelion seeds possess a complex three-dimensional structure and a self-adapted flying ability. To understand this fascinating flight mechanism, a three-dimensional umbrella-shaped model imitating dandelion seeds is proposed. The effects of folding angle and flow velocity on the dandelion drag force during their descent are studied, and it is found that the larger folding angle results in a smaller drag coefficient. Four different vortex structures are revealed depending on the folding angle. The effect of crosswind disturbances on the attitude stability of dandelions is also investigated by changing folding angles. It is found that dandelions with larger folding angles have better attitude stability. The proposed model suggests that when the folding angle is between 20° and 40°, the dandelion seeds might have a good balance between the drag force and attitude stability, which ensures a broad self-adapted flying ability.