Q4. What provides a means of measuring launch valve performance? Q5. What is the purpose of the keeper valve? Q6. What component transfers the forward motion of the pistons to the aircraft? Q7. What system provides a means of lubricating the launching engine cylinders? Q8. The   bridle   tensioning   system   full-aft   limit switch is part of what catapult circuit? Q9. The auxiliary tank of the hydraulic system has a capacity of how many gallons? Q10. What is the function of the retraction engine and drive system? Q11. The    controls    for    the    ICCS    are    divided between what panels? Q12. During operation, what indicates the readiness  of  the  catapult  to  the  launching officer? OPERATIONS LEARNING OBJECTIVE: Describe the operation of a steam catapult. A  steam  fill-valve  system  controls  the  amount  of steam    from    the    ship's    boilers    to    the    wet-steam accumulator. Steam from the steam accumulator is then released  into  the  launching  engine  cylinders  through the launch valve (the amount of steam used is varied by a capacity selector valve [CSV] assembly that controls the launch valve opening rate). This surge of steam acts on a set of steam pistons inside the launching engine cylinders. These pistons are connected to a shuttle that is attached to an aircraft. The force   of   the   steam   being   released   from   the   steam accumulator  pushes  the  pistons  forward,  towing  the shuttle and aircraft at an increasing speed until aircraft take-off is accomplished. The shuttle and steam pistons are stopped at the end of  their  "power  stroke"  as  a  tapered  spear  (fig.  4-68) enters a set of water-filled cylinders, forcing the water to be "metered" out of the cylinders as the tapered spear moves into them. After the shuttle and pistons have been stopped, a grab  is  advanced  forward  along  the  catapult  trough covers by means of the retraction engine, and attaches to  the  shuttle  assembly.  The  retraction  engine  is  then reversed   and   returns   the   grab,   shuttle,   and   piston assembly to the battery position in preparation for the next aircraft launch. A    integrated    catapult    control    station    (ICCS), central  charging  panel  (CCP),  main  control  console, deckedge control panel, retraction engine control/charging panel, and water brake panel are used in   conjunction   to   direct   and   integrate   the   catapult electrical   and   hydraulic   systems   functions   and   to control  the  sequence  of  operations  through  a  normal catapult launching cycle. Preliminary  functional  tests  are  performed  by  all operating personnel. These tests consist of at least two no-load launchings, during which the control system is operated through its complete cycle. The functioning of as  many  component  parts  of  the  catapult  as  possible should be observed by personnel at the various stations 4-56 SHUTTLE SHUTTLE TRACK PISTON GRAB 1. SHUTTLE IN BATTERY POSITION 2. AIRCRAFT ATTACHED TO SHUTTLE AND HOLDBACK UNIT 3. TENSIONER AND GRAB EXERT FORWARD PRESSURE ON SHUTTLE FOR TENSIONING. GRAB AND SHUTTLE UNLOCK A B CATAPULT FIRES 1. HOLDBACK UNIT RELEASES 2. SHUTTLE TOWS AIRCRAFT FORWARD WATER BRAKE REACTION SYSTEM PISTONS AND SHUTTLE HALTED BY WATER BRAKES C D E GRAB ADVANCES AND LATCHES TO SHUTTLE GRAB RETRACTS SHUTTLE TO BATTERY POSITION ABEf0401 AIRCRAFT PREPARED FOR LAUNCH Figure 4-68.—Catapult operation.