The  engine  drawing  as  originally  designed  was  exhibited  at  a
joint  meeting  of  the  Aircraft  Board  and  the  Joint  Army  and  Navy
Technical  Board  on  June  4,  1917,  and  an  opinion  as  to  its  merits
was  requested  from  the  Navy  members  present.  The  consensus  of
opinion  was  that,  as  far  as  could  be  told  from  the  drawing,  it  would
be  satisfactory  except  for  the  piston  there  shown;  a  flat-top  piston
was  recommended  to  reduce  the  compression  in  order  to  satisfy
the  requirements  of  the  Navy's  lower  altitude  work,  to  reduce  spark-
plug difficulties,  and  simplify  the  question  of  cooling.  With  the
single  exception  of  the  piston,  it  was  expected  that  the  Army  and
Navy  engines  would  be  identical.  Later  the  Army  had  to  offset  their
propeller  hub  3  inches  owing  to  the  radiator  shutters  on  the  De
Haviland.  This  offset  hub  gave  the  Navj'  considerable  trouble  later
from  the  fact  that  the  offset-hub  engine  would  not  fit  into  the  HS
flying  boat,  as  it  became  necessary  at  one  time  to  accept  Army
engines  to  keep  production  going.
The  Navy  had  on  order  during  the  war  approximately  4,370  Lib-
erty engines,  and  practically  all  of  these  were  delivered.  The  Air-
craft Board  recommended  that  all  aircraft  production  for  the  Navy
to  be  used  for  antiaircraft  warfare  should  have  priority  in  delivery.
This  recommendation  was  approved  by  the  Secretary  of  War,  and
the  Navy  thus  obtained  the  first  production  of  Liberty  engines,
which  began  from  the  Packard  company  in  January,  1918,  approxi-
mately two  months  behind  the  estimated  schedule.  Practically  all
of  the  Navy's  Liberty  engines  came  from  the  Packard  company.
136         HISTORY   OF   ENGINEERING  DURING  THE   WORLD  WAR.
