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P. Liu
Fig. 7.3 Ancient Greek mythology legend (800 BC)—Cupid (Eros)
a blacksmith who made his first flying wing and began experimenting with
his brother Egil, emphasizing: “It is easy to rise against the wind, when you
want to descend, it is necessary to fly along the wind”. When his brother did
according to his method, he found that the feathers were very stable when
taking off, but they were not stable when falling down following the wind.
This shows that the aircraft has poor performance when flying following the
wind and is prone to instability. Later, Wayland told his younger brother, “I
forgot to tell you that it is good to go against the wind when you come back”.
As can be seen from this story, it has been recognized that airplanes, kites, and
other aircraft are best, most stable and safest taking off and landing against
the wind. Therefore, when you go to the airport to see off, you generally do
not say “flying all the way along the wind”, but it is better to say “have a
pleasant journey”.
In 725 AD, Li Bai wrote in the poem “Letter to Li Yong”: “Roc took
off from the wind and skyrocketed up to 90,000 li. If the wind stops, roc