accumulator  warm-up,  steam  is  available  through  a branch line and valves to the trough warm-up system (fig. 4-3). The launching engine cylinders are heated to operating   temperature   by   a   pair   of   trough   heaters located below each row of launching engine cylinders. The rough heaters are installed in two sections referred to  as  the  forward  and  aft  legs.  Each  trough  heater consists of a pipe within a larger pipe that is capped at the forward end. Steam is admitted into the inner pipe, them flows through the inner pipe into the outer pipe, heating the outer pipe. Fins installed on the outer pipe provide even radiation of heat to the launching engine cylinders,   condensation   from   each   outlet   pipe   is removed by drains lines which are equipped with fixed orifices. The orifices are sized so that water is removed at a rate that will maintain enough steam flow to heat and    maintain    the    launching    engine    cylinders    at operating   temperature,   bypass   valves   are   provided around each orifice to remove excess water if required. STEAM SMOTHERING SYSTEM The   steam   smothering   system   (see   fig.   4-3) provides a rapid means of extinguishing a fire in the catapult  trough  or  in  the  launch  valve  compartment. The launch valve steam smothering is accomplished by admitting  steam  into  a  pair  of  lines  encircling  the launch valve area, holes in these lines direct steam to cover the area. Trough   steam   smothering   is   accomplished   by admitting main steam into a pipe located between the launching  engine  cylinders,  holes  in  the  pipe  direct seam to all of the trough area. Trough steam smothering can be actuated pneumatically by a valve at deckedge or manually by a bypass valve located near the pneumatically operated steam supply valve. WET ACCUMULATOR OPERATION The steam accumulator provides a volume of steam under   pressure   to   the   launch   valve   assembly.   At operating  temperatures,  when  the  launch  valve  opens and  steam  is  released  to  the  launch  engine  cylinders, steam pressure within the accumulator drops, when the pressure drop in the accumulator occurs, the steam fill valve  open  and  admit  steam  into  the  accumulator  by means of a perforated manifold submerged in the water, this  will  rapidly  heat  the  water  back  to  the  operating temperature. Water level will return its pre-established level. LAUNCHING ENGINE SYSTEM LEARNING  OBJECTIVES:   Describe   the components  of  the  launching  engine  system. Describe the function of the launching engine system. 4-3 ABEf0404 CAT STEAM SUPPLY COMPT STEAM SMOTHER CONSTANT STEAM HEATING SUPPLY CAT DK EDGE STA RESERVOIR NOT ON ALL INSTALLATIONS THROUGH HEAT FINNED PIPES (AFT LEGS) TO FWD LEGS FROM FWD LEGS STEAM SMOTHERING PIPING ORIFICE TO SERVICE STM DRAIN DISCH OVBD TO ATMO TO HP DRAINS Figure 4-3.—Trough heat and steam smothering.