vertical flyback period

例句：

1. 1.The vertical flyback period of the engine is critical for its performance.
   发动机的垂直回弹周期对其性能至关重要。
2. 2. During the vertical flyback period, the piston moves back and forth rapidly.
   在垂直回弹期间，活塞快速来回移动。
3. 3. The manufacturer has to consider the vertical flyback period when designing the engine.
   制造商在设计发动机时必须考虑垂直回弹周期。