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ESTABLISHMENT   OF   REFERENCE PLANES
ESTABLISHMENT   OF   BENCHMARK AND  TRAM  REFERENCE  READINGS

Fire Controlman Volume 04-Fire Control Maintenance Concepts
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Equipment  Benchmarks Each  equipment  with  an  alignment  telescope  has a  benchmark  that  can  be  sighted  through  the  tele- scope.  Equipment  benchmarks  are  installed  at  any convenient  location  that  is  visible  through  the  equip- ment  telescope.  These  benchmarks  are  used  through- out  the  life  of  the  ship  to  verify  that  the  alignment  is still  within  tolerance. ESTABLISHMENT   OF   PARALLELISM The  third  major  alignment  step  is  the  establish- ment  of  parallelism  between  the  RPPs  of  all  equip- ment  in  the  combat  system.  The  degree  of  parallelism required  is  based  on  the  design  and  manufacturing criteria,  the  operational  environment,  and  the  require- ments  of  the  various  operational  modes.  The  steps necessary  to  achieve  the  degree  of  parallelism  re- quired   are   inclination   verification,   foundation   ma- chining,   and   interequipment   leveling. Inclination   Verification Inclination   verification   consists   of   measurements of  the  tilt  between  two  RPPs.  The  amount  by  which one  RPP  is  tilted  with  respect  to  another  RPP  is  ex- pressed as the  angle  of  inclination  between  the  planes and  the  bearing  where  this  inclination  occurs.  The  tilt of  the  RPP  is  usually  determined  by  the  two-clino- meter  method  or  the  horizon-check  method. Foundation    Machining Foundation   machining   pertains   to   the   physical processes   required   to   attain   a   specified   degree   of parallelism   and   is   performed   by   a   support   activity. Physical  processes  may  involve  using  milling  ma- chines   or   welding   premachined   surfaces   in   place. Machining  is  accomplished  with  the  ship  afloat  and loaded   to   simulate   the   fill-load-deflection   curve   and the  strains  of  major  concentrated  loads.  The  ship  is kept  in  the  specified  loaded  condition  for  a  sufficient period  of  time  (48  hours)  before  the  start  of  machining operations  to  allow  ship  structural  members  to  adjust to  the  load.  Strict  adherence  to  normal  shipyard  tech- niques  of  machining  during  periods  of  minimum  tem- perature  changes  is  observed. Interequipment    Leveling Interequipment  leveling  is  achieved  by  leveling rings,  shims,  adjusting  screws,  or  software  compensa- tion.  Leveling  capabilities  are  used  to  achieve  the  RPI tolerances  imposed  by  the  minimum  acceptable  re- quirements   or   the   various   operational   modes   of   the combat  system.  Where  leveling  capabilities  are  not provided,  RPI  tolerances  are  achieved  through  foun- dation  machining.  In  cases  where  foundation  machin- ing  is  initially  used  to  meet  these  tolerances,  RPI compensation   through   computer   software   changes may  be  introduced,  if  necessary. PERFORMANCE   OF   FIRE-CONTROL RADAR   RADIO-FREQUENCY OPTICAL   ALIGNMENT The  fourth  major  alignment  step  is  the  verification of   fire-control   radar   radio-frequency   (RF)   optical alignment  (collimation).  During  initial  installation,  the RF  optical  alignment  is  established  and  the  optics  are secured  in  place.  During  subsequent  alignment checks,  the  radar  antennas  or  the  optics,  as  applicable, are   adjusted   to   correct   any   alignment   error   between the  optical  axis  and  the  RF  axis.  When  the  radar  is tracking,  the  RF  axis  is  the  reference  used  for  target location.  RF  optical  alignment  is  an  equipment-level test  and  is  performed  on  a  certified  shore  tower  facil- ity  or,  in  the  case  of  some  radars,  may  be  performed while  tracking  a  target. ESTABLISHMENT  OF  TRAIN  AND ELEVATION   ZERO   ALIGNMENT The  fifth  major  alignment  step  is  the  train  and  ele- vation  zero  alignment.  This  alignment,  performed  by the  ship’s  force  or  a  support  activity,  is  conducted  to ensure   that   all   combat   systems   equipment   points   to the  same  point  in  space  when  so  directed. 3-14






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