The  fuel  consumption  is  reported  to  be  .52  lbs.  per  h.p-hr.,
and  the  oil  consumption  .03  lbs,  per  h.p-hr.    The  compression


Airplane  Engine  Encyclopedia


Curtiss  161

ratio  is  4.91  to  1.  The  weight  is  stated  to  be  417  lbs.,  and  the
water  content  16  lbs.  The  overall  dimensions  are  as  follows :
length  63  in.,  height  39.25  in.  and  width  22.125  in.
The  design  of  the  K-12  engine  has  been  closely  followed
and  as  many  of  the  K-12  parts  as  possible  used  in  the  con-
struction. The  camshaft  driveshaft  stands  vertically  and
drives  the  exhaust  camshaft,  which  is  to  one  side  of  center,
by  virtue  of  skew  bevel  gears.  The  crankshaft  has  a  total
of  five  plain  main  bearings,  one  of  these  being  just  outside  the
annular  ball  bearing  provided  to  carry  the  propeller  thrust.
C-12.  The  Curtiss  C-12  engine  is  a  redesigned  K-12
model  incorporating  the  following  changes.  The  packing
gland  at  the  lower  extremity  of  the  cylinder  barrel  is  omitted
by  bolting  the  aluminum  cylinder  jacket  to  the  crankcase  in-
stead of  casting  it  integral.  Without  changing  cylinder  center
distances  three  intermediate  main  bearings  are  added  by  cut-
ting down  the  width  of  the  bearings  and  the  crank  throws.
Obviously  no  improvement  could  be  effected  thereby.  The
spark  plugs  were  located  diametrically  opposite  instead  of
both  inside  the  Vee  on  the  intake  side,  a  position  which  ap-
parently had  given  satisfactory  results.
The  C-12  engine  is  rated  at  400  h.p.,  but  develops  427  h.p.
at  2250  r.p.m.  The  normal  brake  mean  effective  pressure  is
approximately  131  lbs.  per  sq.  in.  The  fuel  consumption  is
reported  to  be  .503  lbs.  per  h.p-hr.,  and  the. oil  consumption
.083  lbs.  per  h.p-hr.  The  dry  weight  is  said  to  be  705  lbs.,  or
1.649  lbs.  per  normal  h.p.
