*TM 1-1500-204-23-5Change 3 3-53-5 Helicopter Flight Controls. The various helicop-ter controls are explained in the following paragraphs.a. Cyclic Pitch Control. The cyclic pitch controlchanges the tilt of the main rotor for control about thelongitudinal axis (roll) and lateral axis (pitch). It actsthrough a mechanical linkage, as shown in figure 3-4, toincrease the pitch of the retreating blade and decreasethe pitch of the advancing blade on each cycle of rotation.b. Collective Pitch Control. The collective pitchcontrol, as shown in figure3-5, varies the lift of the mainrotor by increasing or decreasing the pitch of all bladesat the same time. Raising the collective pitch controlincreases the pitch of the blades, thereby increasing thelift. Lowering the control decreases the pitch of theblades, causing a loss of lift. Collective pitch control isalso used in coordination with cyclic pitch control to regu-late the airspeed of the helicopter.c. Swashplate. The swashplate assembly trans-mits movement of the flight controls to the main rotorblades. Refer to the applicable maintenance manual forunique features of a swashplate on a specific aircraft.d. Throttle Control. The throttle control is mountedon the collective pitch grip, as shown in figure 3-5, and isoperated by rotating the motorcycle--type grip. Rotatingthe grip outboard increases rpm, and rotating it inboarddecreases rpm.e. TorqueControl. Torque control provides formovement about the vertical axis (yaw). This movementis controlled by the directional--control pedals in the cock-pit.Figure3-4. Cyclic Pitch Control.3-6 Main Rotor Assemblies.Rigid, semi--rigid, andfully articulated rotor assemblies are described in thefollowing paragraphs.a. Semi--Rigid Rotor. In a semi--rigid rotor system,the rotor blades are rigidly interconnected to the hub, butthe hub is free to tilt and rock with respect to the rotorshaft. In this system, only two--bladed rotors are used.The rotor flaps as a unit, that is, as one blade flaps up, theother blade flaps down an equal amount.b. Fully Articulated Rotor. Fully articulated rotorsystems permit individual movement of the blades fromthe hub in both a vertical and horizontal plane. The hingepoints and direction of motion around each hinge areshown in figure 3-6.(1)Blade flapping. The rotor blades are at-tached to the rotor hub by a horizontal hinge which per-mits the blades to move in a vertical plane, and flap upor down, as they rotate, as shown in figure 3-8. In forwardflight and assuming that the blade--pitch angle remainsconstant, the increased lift on the advancing blade willcause the blade to flap up, decreasing the angle of attackbecause the relative wind will change from a horizontaldirection to a more downward direction. The decreasedlift on the retreating blade will cause the blade to flapdown, increasing the angle of attackFigure3-5. Collective Pitch Control.
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