V1：起飞决断速度，超过此速度后，不要中断起飞，否则会冲出跑道。决断速度(Take-Off Decision Speed)

V1：The speed beyond which the takeoff should no longer be aborted. Above V1, the takeoff must be continued unless there is reasonto believe that the aircraft will not fly.

Vr：抬前轮速度，到此速度时飞机前起离地。抬轮速度(Rotation Speed)

Vr ："Rotate": The Speed at which the pilot begins to apply control inputs to cause

the aircraft nose to pitch up, after which it will leave the ground.the aircraft nose to pitch up, after which it will leave the ground.

V2：安全起飞速度，飞机到此速度时，即使有一台发动机失效，也能继续安全爬升。安全起飞速度(Take-Off Safety Speed)

V2: Takeoff safety speed, the speed at which the aircraft may safely climb with one engine inoperative. The takeoff safety speedmust be attained at the 35 ft height at the end of the required runway distance