S-3A VIKING. —The S-3A Viking is a carrier- based,  subsonic,  all-weather,  long-range,  high- endurance,  turbofan-powered  aircraft.  It  can locate and destroy enemy submarines, including newer  high-speed, deep-submergence,  quiet- running  submarines.  The  S-3A  operates  primarily in the middle and outer carrier battle group anti- submarine warfare (ASW) zones with other ASW units—surface,  airborne,  and  subsurface.  It  also can operate independently or in tandem with its long-range,   land-based   ASW   partner,   the   P-3 Orion.   Weapons   carried   by   the   S-3A   include various  combinations  of  torpedoes,  depth  charges, missiles,  rockets,  and  special  weapons. ROTARY-WING    AIRCRAFT The aerodynamics of rotary-wing aircraft are considerably  more  complex  than  those  of  fixed- wing aircraft. A helicopter essentially consists of a  fuselage,  a  main  rotor  or  rotors,  and  often  a tail  rotor.  The  fuselage,  as  in  fixed-wing  craft, contains  the  cockpit  and  cabin. The main rotor is the approximate equivalent of  the  wing  of  a  fixed-wing  aircraft;  each  rotor blade  is  an  airfoil,  like  a  wing.  The  rotation  of the main rotor assembly creates a flow of air over the  blades  that  generates  lift.  The  aerodynamic forces on the rotor lift the helicopter into the air; it  is  not  pushed  up  by  the  downwash.  Some helicopters have twin rotors in tandem at either end of the fuselage. Most have a single, main rotor with a tail rotor mounted at right angles. A few have  tandem  intermeshing  rotors. The  tail  rotor  (on  helicopters  that  have  one) provides  directional  control  and  stability.  It  is mounted  at  right  angles  to  the  main  rotor  to counteract the torque of that system. By varying the  pitch  of  the  tail  rotor  blades,  the  pilot controls  yaw.  By  effectively  tilting  the  entire  main rotor, the pilot determines the pitch and roll. By simultaneously increasing the pitch on all blades on the main rotor, the pilot causes the helicopter to climb. (The pitch is essentially how large a bite of  air  the  blades  take,  as  distinct  from  aircraft pitch.) A  transmission,  which  may  be  disengaged, connects  the  helicopter  engines  to  the  rotor shaft(s). That permits operation of the engine(s) on  the  ground  without  engagement  of  the  rotor system  and  a  mode  of  flight  known  as  auto- rotation. If the engines should stop while in flight, the  pilot  can  disengage  the  transmission;  the freewheeling  action  of  the  rotor  will  then  allow a slower descent. Since World War II, rotary-wing aircraft have become  an  indispensable  part  of  naval  warfare. Their   applications   seem   limitless—ASW;   pilot rescue; transfer of supplies, mail, and personnel within   dispersed   forces;   amphibious   warfare; evacuation  of  wounded;  counterinsurgency; minesweeping; and others. Representative types are  shown  in  figure  12-2. SH-2F Seasprite The Seasprite is a ship-based antisubmarine warfare  (ASW)  and  antiship  surveillance  and targeting  (ASST)  helicopter.  The  SH-2F  is equipped with a search radar, electronic support measures,  magnetic  anomaly  detectors,  and  an acoustic  data  link.  The  helicopter  also  carries active  and  passive  sonobuoys. The  prototype  Seasprite  flew  for  the  first time  in  1959.  Since  then,  many  versions  have been  produced  for  the  Navy  under  its  light airborne multipurpose system (LAMPS) program to  provide  helicopters  for  ASW  and  ASST operations. SH-3H Sea King The  SH-3H  is  a  twin-engine,  all-weather,  ship- based   ASW   helicopter.   It   is   equipped   with variable depth sonar, sonobuoys, data link, chaff, and  a  tactical  navigation  system. The  first  version  of  this  workhorse  ASW helicopter  was  flown  more  than  20  years  ago. The current model is equipped with sonar, active and passive sonar buoys, and magnetic anomaly detection  equipment. The  Sea  King,  also  used  by  some  squadrons for search and rescue missions, is being replaced by  the  SH-60F  Seahawk. UH-46/CH-46 Sea Knight The  Sea  Knight  is  another  example  of  a durable and versatile aircraft that still provides valuable service more than two decades after its first flight. Both the Navy and the Marine Corps have flown various versions of it. The Navy has used  the  UH/CH-46  for  vertical  replenishment, and  the  Marine  Corps  has  used  the  CH-46  for troop  transport.  Both  the  Navy  and  Marine  Corps have used the CH-46 for search and rescue (SAR). The Sea Knight can carry approximately 6,000 pounds of cargo in a sling beneath the fuselage. The CH-46E has been modified with much more powerful engines than earlier Navy and Marine Corps  versions. 12-6