MK 86 GUN FIRE CONTROL SYSTEM
Information Sheet Number: 1.2
The Gun Fire Control System (GFCS) is the primary fire control radar for NGFS, SUW and AW gun engagements. From a Gunnery Officers perspective, the GFCS is the controlling element where loading and firing orders originate. It is essential for the Gunnery Officer to understand the GFCS to get a better perspective of the entire Gun Weapons System.
(a) SW221-BC-MMO-010/MK 86-9
A. EQUIPMENT OVERVIEW
1. MK 86 GFCS is the central sub-element of the Gun Weapons System (GWS). It provides singular or dual remote control of the ship's forward and aft 5"/54 caliber gun mounts to engage up to two targets simultaneously.
2. Operators can select from various GFCS modes from which the system calculates ballistic gun orders. These orders can be modified by console operators to correct for environmental effects on ballistics.
3. The GFCS conducts direct firing attacks against surface radar and optically tracked targets, as well as indirect firing during Naval Gun Fire Support (NGFS).
4. MK 86 GFCS consists of several discrete operational units which can be categorized into the following function related groupings:
a. Radar Set AN/SPQ-9
(1) The AN/SPQ-9 is a high resolution, 2-D, Track While Scan (TWS) radar which can track surface or low flying air targets.
(2) Circuitry within the radar allows for interrogation, tracking and video display of land based beacon transponders for determining own ship's position.
b. Operator Consoles
(1) Control Officers Console (COC) allows the operator to control and monitor overall operation of the GFCS.
(2) The COC provides the following functions:
(a) Controls power application to GFCS units.
(b) Controls operation of the SPQ-9 and displays target video on the Plan Position Indicator (PPI).
(c) Acquires SPQ-9 targets generated and displayed on the PPI and assigns targets to the TWS channels.
(d) Initiates both tactical and non-tactical operating modes of the GFCS.
(e) Selects and monitors Gun Fire Control Console (GFCC) outputs of range, bearing, course, and speed for targets tracked by each of the TWS channels.
(f) Assigns SPQ-9 targets and gun mounts to the Weapons Control Consoles (WCC's).
(g) Enables/disables WCC firing circuits.
(h) Controls Electronic Protection (EP).
(i) Enables the generation of the Low Altitude Detection/Acquisitions (LAD/A) envelope.
(3) Weapons Control Console allows the operator to monitor and maintain SPQ-9 target tracking and to control and monitor gun firing of either one or both of the 5"/54 MK 45 LWGM's.
(4) The WCC performs the following functions:
(a) Provides B-scan video monitoring for tracking SPQ-9 targets, enables operator aided tracking, displays projectile splash points, and enables operator spotting corrections.
(b) Provides Dual Scan Video Monitoring (DSVM) presentation and control for target imagery, computer stored data and camera video.
(c) Manual positioning of the Remote Optical Site (ROS) in bearing and elevation, and for use in aided tracking and spotting corrections.
(d) Data display for operator monitoring of range, bearing, elevation and speed.
(e) Allows for operator entries of environmental data, ballistic data, target data, ammunition selections, spotting corrections, and grid data for NGFS.
c. Data Video Units
(1) Signal Data Translator (SDT) provides:
(a) Address encoding pitch and roll information to GFCC
(b) ROS bearing data, gun fired data and COC and WCC failures
(c) Converts digital gun control data to syncro form for use by the gun mounts
(2) Signal Data Convertor (SDC)
(a) Converts three-wire synchro signals to multiplexed analog Direct Current (DC) signals.
(1) Magnetic Tape Recorder/Reproducer allows for:
(a) Historical data recording
(b) Operational and maintenance program loading
(2) Computer Logic Unit Test Set allows for:
(a) Off line preventative maintenance
(b) Fault isolation
(3) The AN/UYK - 7 or - 43 is the heart of the Gun Fire Control System.
e. Remote Optical Sighting System (ROS)
(1) Optical tracking can be accomplished automatically by slaving ROS to TWS or grid targets assigned to a given WCC, or by manually using the joystick at a WCC.
(2) Optical site system doubles as a sophisticated visual identification asset.
f. Power Central (PC)
(1) PC is the central power control and distribution point for the GFCS.
(2) Power is applied to the GFCS in four steps, termed power levels: pre-standby, standby, operate and radiate.
B. OPERATING MODES
1. NTDS Data Link
a. Surface and air targets are designated to the MK 86 GFCS via the respective warfare coordinator. The warfare coordinator evaluates target threat, makes weapons assignment recommendations, and surveys the tactical situation prior to designating a target to the Gun Weapons System (GWS).
b. The following target information is displayed:
(1) Track number (TN)
(2) Alert Message (ASSIGN GUN/ENGAGE)
(4) Bearing (BRG)
c. Track While Scan (TWS) symbol and acquisition gate appear on the Plan Position Indicator (PPI), a ballistic solution is generated and updated as the target or firing ship maneuvers.
d. Local designations can be initiated from the COC console in a stand alone configuration.
2. Surface Mode Operation
a. The AN/SPQ-9 is the primary GFCS sensor for surface targets
b. Surface mode operations consist of:
(1) Controlling acquisition and tracking of surface/low flying aircraft through target designation manipulation and use of the four track while scan channels.
(2) Providing gun target control data to the GFCS.
c. Target acquisition and tracking are performed by the GFCS in conjunction with the Video Processor (VP).
(1) The GFCS processes target range and bearing data from the VP, using real time data to reposition and vary the size of the target tracking gate.
(2) At the same time the GFCS transmits gate position and console status to the Weapons Control Systems (WCS) computer for target solutions.
3. Grid Mode Operation
a. The Gun Weapons System (GWS) conducts Naval Gun Fire Support (NGFS) missions using direct and indirect firing methods.
(1) Direct firing methods can be employed against targets which are visible to the AN/SPQ-9 or the ROS.
(a) Direct fire provides for rapid engagement of a single, observed target with gun mount firing, spotting and post fire evaluation centralized to a WCC.
(2) Indirect firing is conducted in a grid mode using coordinates of the target and own-ship to calculate target position relative to the ship.
(a) Own ships grid position is calculated by using one of the TWS channels, or it can be determined in the navigation reference mode and beacon sub-modes (discussed later).
(b) Target position is measured from Universal Transverse Mercator Charts.
4. Optical Mode Operation
a. Optical mode operations are used to engage manually tracked targets using the ROS and the DSVM on the WCC's.
(1) The ROS position quantities are processed to calculate target angular data.
(2) The WCC operator enters estimated target range, angle, speed and height.
(3) Centers the target in the DSVM and squeezes the ENTER trigger and enables optically aided tracking. The AN/SPQ-9 radar then provides range and auto angle tracking.
b. This mode is extremely effective against slow moving targets and those with poor radar reflectivity.
5. Training Mode Operation
a. Training mode is a non-tactical mode use to provide a computer controlled simulated SPQ-9 target for training purposes.
b. The COC operator initiates training mode, which disables all four TWS channels, thus disabling the gun firing circuits.
c. The WCS computer then enters the training mode, which allows for designation of training targets on slaved TWS channel 4. TWS channels 1-3 are available for normal use to track either training or live targets.
d. If a live target was being tracked with the training mode in service, the target must be re-acquired upon return to Battle Mode.
6. Test Mode
a. Test mode operations are software oriented within the operational program.
(1) The Test Mode is initiated at the COC console.
(2) With the Test Mode activated targets are generated and displayed on the COC PPI every 45 degrees at ranges of 2, 6, and 10 nautical miles.
b. The following tests are run:
(1) Test number 1 - Simple harmonic motion gun orders test, causes the gun to oscillate between +/- 20 deg in amplitude for 10 seconds. The guns are observed for smooth operation and to ensure the train and elevation errors are within acceptable limits.
(2) Test number 2 - Constant velocity gun orders, used to check gun order conversation circuitry. The gun is remotely controlled from a WCC, through entire horizontal and vertical motion capabilities, at 5 deg/second. The guns are observed for smoothness of motion.
(3) Test number 3 - Fixed position gun orders are generated at 000/180 Deg azimuth, 25 deg elevation with a 10 sec fuse time. Tests the gun's ability to synchronize without significant overshoots at the ordered position.
(4) Test number 4 - Static TWS target and gun orders test the accuracy of the tracking channel, ballistic solution, and gun mount positioning.
(5) Test number 5 - Dynamic TWS target and gun order tests the ability of the gun to track moving targets and generate ballistic solutions.
7. Navigation Mode
a. The AN/SPQ-9 radar is used as a secondary navigation radar during sea and anchor details. TWS channel can be used to generate bearing and range information for navigational fixes.
b. For NGFS operations the MK 86 systems can be used in the following ways:
(1) Generate ships position relative to geographical land mass.
(2) Generate gun orders for grid target orders relative to ships position.
c. The GFCS uses three reference coordinate systems.
8. Anti-Air Warfare
a. The AN/SPG-60 radar is used as the primary fire control radar. Targets are assigned by the ships CDS or C&D (Aegis).
b. CG-47 class ships use the AN/SPY-1A/B radar as the primary fire control radar for air engagements.
9. Target Designation System
a. The Target Designation System provides a secondary source of target data to the GFCS and CDS computers, provides a designation source to the GFCS air track radar and remote television system, and serves as a casualty mode control station for the gun mounts to remotely position the guns on target and initiate gun mount firing.
b. Consists of two Target Designation Transmitters MK 24 mounted topside and one Control Unit MK 79. Installed on board DD-963, DDG-993, CGN-37/41, and LHA-1 class ships.
D. GUN ORDERS
1. Firing procedures are dictated by the type of target being engaged and the firing situation. The number of rounds, type of ammunition and rate of fire are firing procedure considerations as are the selections of high angle ballistics and/or standard/reduced/super powder charges.
2. With the ammunition cells loaded, the WCC operator can examine the loader drum inventory and select from that inventory the type of ammunition for breech loading and firing.
3. The WCC operator can remotely initiate breech loading of the gun mount with the following load orders:
a. Single load
4. When a breech load order is in effect, the rotating drum indexes to the nearest loaded ammunition cell containing the ordered round.
5. With a valid target and gun mount assigned to a WCC and an engaged target within gun mount range, the WCC operator notifies the COC operator as soon as a ballistic solution is attained.
6. The WCC operator initiates gun mount positioning, enters safe firing bearing, orders the loading of the selected rounds, and initiates gun mount firing.
7. When the gun mount is ready to fire, the WCC operator presses and holds the salvo warning alarm and the firing foot key, thus expending the round.
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