Tail rotor driveshaft located inside  of tail body Tail rotor shaft Tail rotor Pitch change links Cross Head Figure 1-9.  Basic tail rotor components. Figure 1-8.  HH-43 Huskie with intermeshing rotors.  powered from the main transmission and a gearbox mounted  at the end of the tail boom.  [Figure 1-9]  The drive shaft may  consist of one long shaft or a series of shorter shafts connected  at both ends with flexible couplings. The flexible couplings  allow the drive shaft to flex with the tail boom.  The gearbox at the end of the tail boom provides an angled  drive for the tail rotor and may also include gearing to adjust  the output to the optimum rotational speed typically measured  in revolutions per minute (rpm) for the tail rotor. On some  larger helicopters, intermediate gearboxes are used to angle  the tail rotor drive shaft from along the tail boom or tailcone  to the top of the tail rotor pylon, which also serves as a vertical  stabilizing airfoil to alleviate the power requirement for the  tail rotor in forward flight. The pylon (or vertical fin) may  also provide limited antitorque within certain airspeed ranges  if the tail rotor or the tail rotor flight controls fail. for a small anti-submarine warfare helicopter, the Flettner  Fl 282 Kolibri. During the Cold War the American Kaman  Aircraft company produced the HH-43 Huskie, for USAF  firefighting purposes. The latest Kaman K-MAX model is  a dedicated sky crane design used for construction work. The tail rotor is a smaller rotor mounted vertically or near- vertically on the tail of a traditional single-rotor helicopter.  The tail rotor either pushes or pulls against the tail to counter  the torque. The tail rotor drive system consists of a drive shaft  The cyclic control is usually located between the pilot’s legs  and is commonly called the “cyclic stick” or simply “cyclic.”  On most helicopters, the cyclic is similar to a joystick;  however, Robinson helicopters have unique T-bar cyclic  control systems. A few helicopters have cyclic controls that  descend into the cockpit from overhead while others use side  cyclic controls. The control is called the cyclic because it can vary the pitch  of the rotor blades throughout each revolution of the main  rotor system (i.e., through each cycle of rotation) to develop  unequal lift (thrust). The result is to tilt the rotor disk in a  particular direction, resulting in the helicopter moving in that  direction. If the pilot pushes the cyclic forward, the rotor disk  tilts forward, and the rotor produces a thrust in the forward  direction. If the pilot pushes the cyclic to the side, the rotor  disk tilts to that side and produces thrust in that direction,  causing the helicopter to hover sideways.  [Figure 1-10] The collective pitch control, or collective, is located on the  left side of the pilot’s seat with a pilot-selected variable  friction control to prevent inadvertent movement. The  collective changes the pitch angle of all the main rotor blades  1-5 Collective  Cyclic  Tail Rotor Controlling Flight A helicopter has four primary flight controls:  • Cyclic • Collective •  Antitorque pedals • Throttle