At 300kph, the air passing over the advancing blade could reach 1,100kph while that over the retreating blade would be about 500kph.

速度为300kph时，通过前面浆片的空气速度可达1100kph，而尾部浆片上的速度大约500kph。

youdao

But when flying forward the air passing over the blade that is advancing to the front of the helicopter (and so into oncoming air) provides more lift than the one that is retreating to the back.

但是当向前飞行时，它的旋翼将转向直升飞机的前方(如此一来，就变成朝向迎面而来的空气)，经过叶片上方的气流将比经过叶片背面的气流产生更大的升力。

youdao

But when flying forward the air passing over the blade that is advancing to the front of the helicopter (and so into oncoming air) provides more lift than the one that is retreating to the back.

但是当向前飞行时，它的旋翼将转向直升飞机的前方(如此一来，就变成朝向迎面而来的空气)，经过叶片上方的气流将比经过叶片背面的气流产生更大的升力。

youdao