Page 12 - Wire Rope News & Sling Technology
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continued from page 10
           The availability of lightweight tur-
         boshaft engines in the second half of
         the  20th  century  led  to  the  develop-
         ment of larger, faster, and higher-per-
         formance  helicopters.  While  smaller
         and  less  expensive  helicopters  still
         use piston engines, turboshaft en-
         gines are the favored power plant for
         helicopters today.
           Uses  for  the aircraft  have only ex-
         panded with time. Due to the operating
         characteristics  of the helicopter—its
         ability to take off and land vertically,
         and to hover  for extended periods of
         time, as well as the aircraft’s handling
         properties  under  low  airspeed condi-
         tions—it has been chosen to conduct
         tasks that were previously impossible
         with other aircraft, or were time- or
         work-intensive  to accomplish on the
         ground. Today, helicopter uses include
         transportation of people and cargo,
         military  uses,  construction,  firefight-
         ing, search and rescue, tourism, medi-
         cal transport, law enforcement, agri-
         culture, news and media,  and aerial
         observation, among others.
           Helicopters  first  saw  use  as  aerial
         cranes  in  the  1950s, but  it  was  not
         until  the  1960s that their  popularity
         as an important piece of equipment in   Heavy-lift longline with electrical cable for remote
         building and other industries began to   hook operations. Photo courtesy of Barry Cordage Ltd.
         catch  on.  The  most consistent  use  of
         helicopters as aerial cranes is in the   to the use of the long, single sling line   er capable  of carrying more than just
         logging industry lifting big trees out   used to carry the load.      a few hundred pounds of cargo. In the
         of rugged terrain where vehicles aren’t   Bell helicopters were the first, light-  1960s, the Sikorsky S-58 came into use
         able to reach, or where environmental   weight aerial cranes to be used in the   due to a larger power margin. Even to-
         concerns prohibit construction of roads.   early 1950s. Regrettably,  due to the   day, S-58s can be found carrying medi-
         Such operations are called longline due   helicopter’s limited power, it was nev-  um-size loads.
                                                                                 The 1960s saw the use of the Bell 211
                                                                               HueyTug,  a  specially-designed com-
                                                                               mercial  type of  the  UH-1C for  lifting
                                                                               medium loads;  even  the  popular  Bell
                                                                               206 was used for light loads. However
                                                                               the demand for an aircraft able to pull
                                                                               up even bigger loads lingered.
                                                                                 Larger helicopters became commer-
                                                                               cially available after the Vietnam War.
                                                                               Helicopter manufacturers  focused on
                                                                               selling commercial versions of their
                                                                               military aircraft. Such  manufactur-
                                                                               ers as Boeing, with their Vertol Model
                                                                               107 and Model 234 aircraft found use
                                                                               in lifting much heavier payloads than
                                                                               their lighter predecessors.
                                                                                 But the heaviest loads required a
                                                                               pure aerial crane.  The answer came
                                                                               from Sikorsky’s S-64 Skycrane. In the
                                                                               beginning produced for the military as
                                                                               the CH-54 Tarhe for massive lifting of
                                                                               downed aircraft and artillery pieces;
                                                                               the  S-64  Skycrane  was  nothing  more
                                                                               than just  enough  airframe to attach
         A Merlin helicopter comes in to drop off a Remover 3.1 mast during a snowy morning.
         © Crown Copyright 2010                                                                 continued on page 14
         12     Wire Rope News & Sling Technology   August 2017
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