简述了飞机斤斗飞行的基本运动关系和操纵动作要领。

First it analyses the basic movement relation and states control actions shortly in the single plane loop.

八只海鸥，一个接一个，陡直向上跃升，翻了个斤斗，又兜了个圈子，以极慢的速度，直立着降落在沙滩上。

One by one, each of the eight birds pulled sharply upward into a full loop and flew all the way around to a dead-slow stand-up landing on the sand.