Zero lift angle

…Symmetrical wings and flat plates do not generate lift at an angle of attack of 0 degrees, but as the angle of attack is increased and the leading edge is raised, the airflow becomes similar to that of an airfoil with a stronger curvature on the top than on the bottom, and lift is generated. For airfoils with a stronger curvature on the top or curved plates, lift becomes zero at a downward angle of attack (between 0 and -6 degrees, and the greater the curvature, the more downward). This angle of attack is called the zero lift angle, and if the leading edge is raised above this, lift begins to be generated. Lift increases as the angle of attack increases, but if the angle of attack is too large, the airflow cannot keep up with the top of the wing, and it separates and swirls, which actually reduces lift. …

*Some of the terminology that mentions "zero lift angle" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…対称翼や平板は迎え角0度では揚力を生じないが，迎え角を増して前縁を上げていくと，空気の流れ方が，上面の湾曲が下面より強い翼型と似てきて揚力を生ずる。上面の湾曲が強い翼型や反った板では揚力が0になるのは下向きの迎え角のとき(0度から－6度くらいまでの間で，湾曲が大きいほど下向きになる)で，このときの迎え角を零揚力角あるいはゼロ揚力角zero lift angleといい，これより前縁を上げると揚力が出始める。揚力は迎え角を増すほど大きくなるが，迎え角を大きくしすぎると気流が翼上面についていけなくなり，途中ではがれて渦を巻くので，揚力が逆に減ってしまう。…

※「zero lift angle」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報