HI.X.C.K4

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• Helicopter Flying Handbookp. 1-4
  Chapter 1: Introduction to the Helicopter › Rotor System › Tandem Rotor

  Tandem Rotor Tandem rotor (sometimes referred to as dual rotor) helicopters have two large horizontal rotor assemblies, instead of one main assembly and a smaller tail rotor. [Figure 1-6] Single rotor helicopters need a tail rotor to neutralize ... twisting momentum produced by the single large rotor. Tandem rotor helicopters, however, use counter-rotating rotors, each canceling out the other’s torque. Counter-rotating rotor blades will not collide with and destroy each other if they flex into…

• Helicopter Flying Handbookp. 2-25
  Chapter 2: Aerodynamics of Flight › Turning Flight

  Figure 2-45. Forces acting on the helicopter during turning flight. Autorotation is the state of flight where the main rotor disk of a helicopter is being turned by the action of air moving up through the rotor rather than ... engine power driving the rotor. In normal, powered flight, air is drawn into the main rotor disk from above and exhausted downward, but during autorotation, air moves up into the rotor disk from below as the helicopter descends. Autorotation…

• Helicopter Flying Handbookp. 2-15
  Chapter 2: Aerodynamics of Flight › Hovering Flight › Translating Tendency (Drift)

  Translating Tendency (Drift) During hovering flight, a single main rotor helicopter tends to move in the direction of tail rotor thrust. This lateral (or sideward) movement is called translating tendency. [Figure 2-27] To counteract this tendency, one or more ... following features may be used. All examples are for a counterclockwise rotating main rotor disk. Figure 2-27. A tail rotor is designed to produce thrust in a direction opposite torque. The thrust produced by the tail rotor is sufficient…

• Helicopter Flying Handbookp. 4-11
  Chapter 4: Helicopter Components, Sections, and Systems › Transmission System › Dual Tachometers

  Main Rotor Transmission The primary purpose of the main rotor transmission is to reduce engine output rpm to optimum rotor rpm. This reduction is different for the various helicopters. As an example, suppose the engine rpm of a specific helicopter ... rotor speed of 450 rpm would require a 6:1 reduction. A 9:1 reduction would mean the rotor would turn at 300 rpm. Dual Tachometers Most helicopters use a dual-needle tachometer or a vertical scale instrument to show…

• Helicopter Flying Handbookp. 1-4
  Chapter 1: Introduction to the Helicopter › Rotor System › Intermeshing Rotors

  Coaxial Rotors Coaxial rotors are a pair of rotors turning in opposite directions, but mounted on a mast, with the same axis of rotation, one above the other. This configuration is a noted feature of helicopters produced by the Russian ... Kamov helicopter design bureau. [Figure 1-7] Intermeshing Rotors Intermeshing rotors on a helicopter are a set of two rotors turning in opposite directions, with each rotor mast mounted on the helicopter with a slight angle to the other…

• Helicopter Flying Handbookp. 4-6
  Chapter 4: Helicopter Components, Sections, and Systems › Main Rotor System › Tandem Rotor

  metal-to-metal contact of older bearings and the need for lubrication is eliminated in this design. Tandem Rotor Tandem rotor (sometimes referred to as dual rotor) helicopters have two large horizontal rotor assemblies; a twin rotor system, instead ... main assembly, and a smaller tail rotor. [Figure 4-10] Single rotor helicopters need an anti-torque system to neutralize the twisting momentum produced by the single large rotor. Tandem rotor helicopters, however, use counter-rotating rotors, with each canceling…