Swash plate Horizontal stabilizer 70 5 30 85 50 15 100 Twist grip throttle Collective control Throttle cable Throttle linkage Fuel control or carburetor Figure 1-12.  The horizontal stabilizer helps level the helicopter to  minimize drag during flight. Figure 1-11.  The throttle control mounted at the end of the collective  control.  1-6 Figure 1-10.  Cyclic controls changing the pitch of the rotor blades.  Flight Conditions Antitorque Pedals Throttle  The throttle controls the power produced by the engine, which  is connected to the rotor by a transmission. The purpose of  the throttle is to maintain enough engine power to keep the  rotor rpm within allowable limits to produce enough lift for  flight. In single-engine helicopters, if so equipped, the throttle  control is typically a twist grip mounted on the collective  control, but it can also be a lever mechanism in fully  governed systems. Multi-engine helicopters generally have  a power lever or mode switch for each engine.  [Figure 1-11] Helicopter flight controls are discussed in greater detail  throughout Chapter 4, Helicopter Components, Sections  and Systems. There are two basic flight conditions for a helicopter: hover  and forward flight. Hovering is the most challenging part of  flying a helicopter. This is because a helicopter generates  its own gusty air while in a hover, which acts against the  fuselage and flight control surfaces. The end result is the  need for constant control inputs and corrections by the pilot  to keep the helicopter where it is required to be. Despite  the complexity of the task, the control inputs in a hover are  simple. The cyclic is used to eliminate drift in the horizontal  direction that is to control forward and back, right and left.  The collective is used to maintain altitude. The pedals are  used to control nose direction or heading. It is the interaction  of these controls that makes hovering so difficult, since an  adjustment in any one control requires an adjustment of the  other two, creating a cycle of constant correction.  collectively (i.e., all at the same time) and independently of  their positions. Therefore, if a collective input is made, all  the blades change equally, increasing or decreasing total  lift or thrust, with the result of the helicopter increasing or  decreasing in altitude or airspeed. The antitorque pedals are located in the same position as the  rudder pedals in a fixed-wing aircraft and serve a similar  purpose, namely to control the direction in which the nose  of the aircraft is pointed. Application of the pedal in a given  direction changes the pitch of the tail rotor blades, increasing  or reducing the thrust produced by the tail rotor, causing the  nose to yaw in the direction of the applied pedal. The pedals  mechanically change the pitch of the tail rotor, altering the  amount of thrust produced. Displacing the cyclic forward initially causes the nose to  pitch down, with a resultant increase in airspeed and loss  of altitude. Aft cyclic initially causes the nose to pitch up,  slowing the helicopter and causing it to climb; however, as  the helicopter reaches a state of equilibrium, the horizontal  stabilizer helps level the helicopter to minimize drag, unlike  Helicopter rotors are designed to operate at a specific rpm. 