achieves maximum upflapping displacement over the nose and maximum downflapping displacement over the tail. This causes the tip-path plane to tilt to the rear and is referred to as blowback. Figure 3-16 shows how the rotor disc was originally oriented with the front down follow- ing the initial cyclic input, but as airspeed is gained and flapping eliminates dissymmetry of lift, the front of the disc comes up, and the back of the disc goes down. This reorientation of the rotor disc changes the direction in which total rotor thrust acts so that the helicopter’s for- ward speed slows, but can be corrected with cyclic input. ward. Drag now acts forward with the lift component straight up and weight straight down. [Figure 3-18] In sideward flight, the tip-path plane is tilted in the direc- tion that flight is desired. This tilts the total lift-thrust vector sideward. In this case, the vertical or lift compo- nent is still straight up and weight straight down, but the horizontal or thrust component now acts sideward with drag acting to the opposite side. [Figure 3-17] In forward flight, the rotor disc is tilted forward, which also tilts the total lift-thrust force of the rotor disc for- ward. When the helicopter is banked, the rotor disc is tilted sideward resulting in lift being separated into two components. Lift acting upward and opposing weight is called the vertical component of lift. Lift acting hori- zontally and opposing inertia (centrifugal force) is the horizontal component of lift  (centripetal force) . [Figure 3-19] As the angle of bank increases, the total lift force is tilted more toward the horizontal, thus causing the rate of turn to increase because more lift is acting horizontally. Since the resultant lifting force acts more horizontally, the effect of lift acting vertically is deceased. To compen- sate for this decreased vertical lift, the angle of attack of the rotor blades must be increased in order to maintain altitude. The steeper the angle of bank, the greater the angle of attack of the rotor blades required to maintain altitude. Thus, with an increase in bank and a greater angle of attack, the resultant lifting force increases and the rate of turn is faster. Autorotation is the state of flight where the main rotor system is being turned by the action of relative wind For rearward flight, the tip-path plane is tilted rear- ward, which, in turn, tilts the lift-thrust vector rear- Resultant Lift Thrust Drag Resultant Weight HelicopterGLYPH<.notdef> Movement HelicopterGLYPH<.notdef> Movement Weight Drag Resultant Thrust Lift SIDEWARD FLIGHT TURNING FLIGHT REARWARD FLIGHT AUTOROTATION Figure 3-16. To compensate for blowback, you must move the cyclic forward. Blowback is more pronounced with higher airspeeds. Figure 3-18. Forces acting on the helicopter during rearward flight. Figure 3-17. Forces acting on the helicopter during sideward flight. Centripetal Force—The force opposite centrifugal force and attracts a body toward its axis of rotation. 3-8