7 Flight Mystery and Aerodynamic Principles
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Fig. 7.4 Ancient Greek mythology legend (800 BC)—Daedalus and his son plugging
in wings and fleeing
will stop at the surface of the water, and its power will be able to dry the
water”. From the flight principle of roc, the first sentence says that when the
wind speed reaches a certain value, roc can use the wind power to skyrocket.
Because only when the relative speed of the wind and the wing reaches a
certain value, it can generate enough lifting force. The second sentence says
that if the wind stops, roc stops on the water, and the airflow generated by
the wings can still raise the water on the river. That is, although the wind has
stopped, the airflow generated by the relative movement between the wings
and the air can also stimulate the water. It can be seen that Li Bai had noticed
that the relative movement between the wings and the air could generate a
lifting force, indicating that Li Bai’s observation of the bird flight was very
detailed. Here, roc refers to the big bird in “Zhuangzi A Happy Excursion”
(as shown in Fig. 7.7). It is recorded in the article: “In the northern ocean
there is a fish, called the kun, I do not know how many thousand li in size.