R2D2 with Attitude: The Story of the Phalanx Close-In Weapons System (CIWS) byRobert H. Stoner, GMCM
(SW) (Ret) Phalanx is a Close-In Weapons System (CIWS) designed as a last chance, point defense, automated gun system designed to destroy in-bound anti-ship cruise missiles.� Phalanx is a design from General Dynamics Corporation, Pomona Division.� Its current manufacturer is Raytheon Company.� Phalanx is found aboard every class of U.S. Navy ship,
Coast Guard cutters of the Hamilton, Legend, and National Security classes,
and in the navies of 23 allied nations. Phalanx has been nicknamed �R2D2� after the famous android from the movie �Star Wars� by people in the U.S. Navy.� Royal Navy sailors call it them �Daleks� after the aliens in the long-running �Doctor Who� television series.�� In recent years, the U.S. Army has been testing a land version of Phalanx called �C-RAM� for Counter-Rocket, Artillery, and Mortar system.� The C-RAM is a Phalanx module with an on-board generator and control station mounted on a low flatbed trailer. History
On 21 October 1967, during the Arab-Israeli �Six Day War�, three Soviet-designed SS-N-2 �Styx� missiles from two Egyptian-manned, Soviet-supplied Komar-class missile craft attacked and sank the Israeli destroyer INS EILAT (K40) off Port Said, Egypt.� EILAT was the ex-HMS ZEALOUS (R39), a former British WW2 destroyer of the �Z� class.�� The sinking of the EILAT caused a major panic among the world�s navies and kicked point-defense systems into high gear. �Until the EILAT�s sinking, fleet air defense had concerned itself with the destruction of attacking manned aircraft.� Defeating a small, fast, low-flying threat represented by an unmanned cruise missile was a completely different story.� Worse, these anti-ship missile (ASM) systems could be fielded and operated by small countries with devastating effects.
Above: The attacked � INS EILAT (K40) [ex-HMS
ZEALOUS (R39)] as she was at the time of the Arab-Israel Six Day War. (Photo:
Israeli Navy) Below: The attackers � two Komar missile attack
craft of the United Arab Republic (Egyptian) Navy.� (Photo: UAR Navy)
Above: The attack on EILAT of 21 October 1967 � from
the Egyptian newspaper "Al Gomhoreya" � with English
captions from the Arabic.� (Art: "Al
Gomhoreya" via Bob Stoner) Below: A Soviet SS-N-2 Styx missile on its
transporter.� The solid rocket booster
is not fitted.� Styx is a large bird at
21.8 ft (6.6m) by 8.2 ft (2.5 m) by 2.6 ft (0.8 m); launch weight is 5,562 lb
(2,523 kg); warhead is 1,050 lb (480 kg); speed is 1.3 Mach; min range is 4
miles (8 km), max range is 40 miles (80 km).��
(Photo: Russian Navy) The Navy approached ASM defense as both a surface-to-air (SAM) missile problem and as a gun problem.� The first SAM system specifically designed to deal with the ASM problem was the Basic Point Defense Missile System or BPDMS.� The BPDMS was first tested aboard USS BRADLEY (FF-1041) in February 1967.� The BPDMS used eight modified RIM-7E Sea Sparrow missiles in an eight-cell Mk 25 launcher that was a scaled-down version of the Mk 112 launcher for the ASROC (Anti-Submarine Rocket).� The Mk 115 fire control radar system provided targeting for the RIM-7E.� Missile range was about 10 to 16 miles with a 65-pound high explosive, continuous rod warhead. Below: The Basic Point Defense Missile System
(BPDMS) was composed of the Mk 115 fire control director and Mk 25
launcher.� The Mk 115 director was a
manned system as shown in this photo taken aboard USS DWIGHT D.� EISENHOWER (CVN-69). �(Photo: U.S. Navy)�
Above: The Mk 25 launcher for Sea Sparrow aboard the Knox-class frigate USS JOSEPH HEWES (FF-1078).� (Photo: Tom Oshgan)� Meanwhile, General Dynamics Corporation, Pomona Division, started with the Army�s self-propelled M163 Vulcan Air Defense System (VADS) to produce an automated version for naval service.� The new weapon was called Vulcan-Phalanx (shortened to Phalanx).� The prototype Phalanx was installed aboard USS KING (DLG-10/DDG-41) in 1973 for evaluation.� Another prototype CIWS was used in tests conducted aboard ex-USS ALFRED A. CUNNINGHAM (DD-752).� Several different kinds of missiles were fired at CUNNINGHAM; all were shot down.� Full operational and evaluation trials were performed aboard USS BIGELOW (DD-942) in 1977. Phalanx met and exceeded all maintenance and reliability requirements.� The first production units of Phalanx were installed aboard USS CORAL SEA (CV-43) in 1980.� Installation aboard noncombatant ships began in 1984.� Block 1 was deployed aboard USS WISCONSIN (BB-64) in 1988.� Block 1B was deployed aboard USS UNDERWOOD (FFG-38) in 1999 and was operational aboard USS TAYLOR (FFG-50) in 2000.
Above: The M163 Vulcan Air Defense System (VADS) as installed on the M113 armored personnel carrier.� This M163 VADS of the 24th Infantry Division is shown at the Fort Irwin National Training Center on 1 November 1988.� (Photo: U.S. Army)� Below: The very first Phalanx prototype aboard USS
KING (DLG-10/DDG-41).� The gun was
located on the fantail of the ship as shown in the insert.�
Above: A production Phalanx Block 1A firing.� Note the enlarged ammunition drum and different gun support� yokes that support the gun and radome.� (Photo: U.S. Navy) The Falklands War between the UK and Argentina [1982] raised further questions about the effectiveness of ASM defense.� Accordingly, the latest version of the Mk 15 Mod 0 Phalanx, called the Block 0, was installed aboard the test ship ex-USS STODDARD (DD-566) in November 1983.� A year long round of real world tests against all kinds of targets � including live warheads � were undertaken.� Lessons learned from these tests were incorporated into the Block 1 version of Phalanx.� From June 1985 through early 1990 extensive tests against Block 1 Phalanx were conducted aboard STODDARD that led to Block 1, Baseline 1 and 2 improvements.� These tests led to the development of the Block 1A variant that introduced an updated computer with software designed to engage targets doing high-G and diving maneuvers.� Design
The Phalanx uses the M61-series Vulcan Gatling gun
rotary cannon firing the 20x102mm round.�
The M61-series gun has six barrels; Block 0 and 1A barrels are 76
calibers (1,520mm or 60 inches) long and Block 1B barrels are 99 calibers
(1,980mm or 78 inches) long.�� The
ammunition has electric primers and is carried in a drum below the gun.� The drum uses a helical screw to feed ammunition
to the gun.� The drum has a capacity of
990 or 1,550 rounds.� Live ammunition is carried to the gun by a linkless feed system; fired cases are returned from the gun for storage in the drum by the same linkless feed system.� No ammunition links are used while the gun is in operation to assure a smooth feed cycle.
Above: The timeline of Phalanx development beginning
with the Mk 15 Mod 0 Block 0.�
(Artwork: Raytheon) On Block 0
reloading of the drum can take between 10 to 30 minutes if loaded from
prelinked ammunition boxes.� Block 1
and later guns use a preloaded ammunition loader/unloader cart.� The loader/unloader cart uses linked live
ammuntion and a drum loader adapter.�
The linked ammunition is connected to the adapter (yellow part in the
photos) that attaches to the end of the drum.�
The adapter turns the screw feeder of the drum to bring fired cases to
the mouth of the drum.� Live rounds
that enter the adapter have their links stripped off.� A feed chute moves the delinked live
ammuntion to the bottom of the drum where it enters to begin the reloading
cycle.� The stripped links are
recycled.� The adapter relinks them to
the fired cases as they come out of the end of the drum.� The relinked empty cases are stowed aboard
the cart or ammunition boxes. Above: Loading Mk 149 Mod 4 ammunition into the Phalanx
drum on USS GEORGE WASHINGTON (CVN-73) in January 2004.� The live ammunition is going in and the
fired cases are coming out � both linked.�
The split line of the discarding sabot projectile is very prominent in
this shot.� (Photo: U.S. Navy)� Above: A closer look at loading Mk 149 Mod 4
ammunition into the Phalanx feeder drum.�
The yellow part is the delinker/linker adapter for the drum. �(Photo: PH1 Tina M. Ackerman) Below: A sectioned view of the Mk 149 Mod 4
cartridge.� (Artwork: General Dynamics
Corp.) The 20x102mm
ammunition for the Mk 15 Mod 0 uses a heavy metal penetrator to knock down
aerial targets.� Mk 149 or Mk 244
projectiles have no explosive filler.�
The Mk 149 Mod 0 and Mod 2 projectiles use a depleted uranium
sub-caliber penetrator.� The Mk 149 Mod
4 and Mk 244 Mod 0 rounds use a tungsten or tungsten alloy steel
penetrator.� Mk 149 Mod 4 rounds use a
red tracer element.� Range of the Mk
149 Mod 4 projectile @ 45 degrees is 6,000 yards (5,500 meters); maximum
effective range is 1,625 yards (1,490 meters). Above: The M61-series gun uses the 20x102mm cartridge
(left).� It is shown compared to the
20x110mm cartridge used by the M3, M24, Mk 12 and Mk 16 20mm machine guns of
the USAF and USN.� (Photo: Anthony G.
Williams) Because the
20mm projectile of Phalanx contains no explosive filler, the kill mechanism
for this round is either warhead detonation of the target (a hard kill) or
aerodynamic disintegration of the missile airframe caused by the high-speed
slipstream over the damaged areas (a soft kill).� The Mk 244 Mod 0 cartridge is known as the
ELC (Enhanced Leathality Cartridge).�
It has a more aerodynamic tungsten alloy penetrator that gives an
increase in effective range.� Muzzle
velocity is 3,650 feet per second (1,113 meters per second) for the Mk 149
cartridge. The Mk 15 Mod 0
Phalanx is broken down into the M61A1 20mm rotary cannon and the Mk 72
mount.� The Mk 72 mount contains the
hydraulics, pneumatics, computers, power drives, power supplies, and coolant
water pumps. Above: The anatomy of the Mk 15 Mod 0 Phalanx: (1) Ku band search radar; (2) Ku band tracking and gun laying radar; (3) M61A1 20mm Gatling-type rotary cannon; (4) helical feed ammunition drum and linkless feed system; (5) elevation power drive; (6) computer modules; (7) hydraulics, pneumatics, train power drive, power supply, and cooling water pump.� (Artwork: General Dynamics Corp. via Bob Stoner)� � Upgrades The Mk 15 Mod 0
is the base model of Phalanx.� Blocks 0
and 1 have a hydraulic drive for the M61A1 gun that produces a cyclic rate of
3,000 rounds per minute.�� Block 0 guns
have a 990 round magazine.� Block 1
guns have a 1,550 round magazine. �Block 1A and 1B have 1,550 round magazines
and a pneumatic gun drive that produces a 4,500 rounds per minute cyclic
rate.� Block 1B guns use an
electro-optical sighting system and have anti-air and anti-surface
capabilities lacking in Block 0 through 1A. ���
�
Above: A Mk 15 Mod 0 Block 1 or 1A gun on the left
compared to a Block 1B gun on the right.�
The major recognition features are longer gun barrels, barrel clamp,
barrel brace, and electro-optical equipment on the side of the radome
instantly identifies the Block 1B variant.�
(Photos: U.S. Navy)
Train is unlimited, but software and mechanical stops prevent firing into the ship�s structure.� Elevation of the gun has increased during the various Blocks; Block 0 is �10 to +80 degrees, Block 1 is �20 to +80 degrees, Block 1B is �25 to +85 degrees.� All Phalanx systems in U.S. service are being brought to Block 1B standard.�� Block 1B systems can be linked with the RIM-116 Rolling Airframe Missile (RAM) or SeaRAM systems.� These systems use modifications of the Mk 72 mount for the M61A1 gun.�Operation
CIWS is
designed to be a bolt-on system.� The
Mk 72 mount only requires a working circle of 18 feet (5.5 metres) of clear
deck, 440 VAC, 3-phase, 60 Hz, and 115 VAC, 60 Hz electrical power, a ship�s
heading input, and a saltwater coolant line delivering 20 gallons per minute
at 30 psig (30 litres per minute at 2 kilograms per square centimetre).� The Mk 340 weapons control panel is located
in the ship�s Combat Information Center (CIC), but there is a Mk 339 local
control panel located close to the gun for system operational checks.� Phalanx is designed to be a stand alone
system, but it can accept inputs from the Aegis Combat System on major
warships. Above: A Mk 15 Mod 0 Block 1B CIWS being hoisted aboard
the new USCG cutter Berthof (WSML-750) in Pascagoula, Mississippi, on 13
November 2008.� The self-contained
nature of the Phalanx CIWS is demonstrated in this photo� (Photo: USCG) � CIWS has two
radar antennas.� The upper antenna is
the search radar that rotates at 90 revolutions per minute.� This is a Ku band digital moving track
indicator radar.� The lower, orange
peel-shaped antenna is the fire control radar or tracking antenna.� This radar is a Ku band digital pulse
doppler mono-pulse radar. � Phalanx uses
closed loop spotting and target prioritizing.�
The search radar identifies the target at 10 nautical miles and the
software begins tracking.� At the same
time, the software compares the target track against its threat logic.� The threat logic determines the pirority
assigned to the target.� Phalanx does
not recognize an IFF (Identification Frend or Foe) signal from an on-board
transponder on friendly aircraft.� Instead,
the target threat software makes the decision to engage or not and the priority
of engagement. Target
assignment and priority are done at 5 miles and engagement begins at or about
2 miles.� Once the software determines
that the threat is in range, the gun opens fire. The tracking (fire control)
radar monitors the outbound projectile stream.� Closed loop spotting is used; that is, the
outbound projectile stream is compared to the inbound target track and the
gun drives are adjusted to move the projectile stream onto the target.� Usually, the third projectile out the
barrel is on target.� Phalanx
considers the target �killed� when it disappears from the radar (blows up or
crashes into the sea � a �hard kill�) or if there is an abrupt change in
target speed and direction that accompanies a breakup of the target�s
airframe (a �soft kill�).� Once a hard
or soft kill on the target is made, Phalanx will engage the next threat.� Up to six threats can be processed at a
time. Engagement
criteria. 1. Is the
range of the target increasing or decreasing relative to the ship?� CIWS discards outbound targets.� Only inbound targets are considered. 2. Can the
contact maneuver to hit the ship?� CiWS
considers target heading in relation to the ship and its speed when
determining whether it can hit the ship. 3. Does
the target speed fall within engagement minimum and maximum speeds?� CIWS will not engage targets outside these
minmum and maximum limits.� However,
the CIWS operator can adjust the limits manually. Engagement scenario. 1.
Phalanx is turned ON and in AUTO mode,
with its magazine loaded and ammunition fed to the gun. 2.
Search radar acquires inbound threat
at 10 miles; Phalanx software starts track, assigns priority. 3.
Search radar continues track; software confirms threat; fire
control radar locks onto target at 5 miles. 4.
About 2 miles (or at optimal range assigned by software) gun
opens fire on Threat 1 and continues until a hard or soft kill is achieved. 5.
Phalanx switches to engage Threat 2 or ceases fire. 6.
Phalanx continues to search for threats. 7.
Phalanx drum is reloaded at first opportunity. Phalanx
in Combat
On 17 March
1987, Iraqi F1 fighter-bombers armed with French-built AM39 �Exocet� missiles
attacked USS STARK (FFG-31).�� Two AM39
missiles hit forward of the bridge portside; one did not explode and spewed
burning propellant inside the ship while the other penetrated the crew
quarters.� Thirty-seven American
sailors were killed and 21 were wounded.�
The Mk 15 Phalanx was in STANDBY mode and did not engage.� Mk 36 Super Rapid Bloom Off-board Chaff
(SRBOC) countermeasures were not armed.�
The SM-1 Standard missile could not engage because the Iraqi F1 was in
the blind spot of the ship�s STIR (Separate Target Illumination Radar).� Phalanx failed because it was not turned
ON.
During the
first Gulf War, USS JARRETT (FFG-33) was operating several miles from USS
MISSOURI (BB-63) and the British destroyer HMS GLOUCESTER (D96) on 25
February 1991.� On that day, the ships
were attacked by an Iraqi Silkworm missile (a Chinese copy of the Soviet
SS-N-2 Styx).� MISSOURI fired its Mk 36
SRBOC decoys.� JARRETT�s Phalanx was
operating in automatic target acquisition mode and malfunctioned, targeted
MISSOURI�s chaff cloud, and fired a burst.�
Four rounds hit MISSOURI which was about 3 miles (5 km) away from
JARRETT.� There were no injuries.� GLOUCESTER fired a Sea Dart missile that
destroyed the Iraqi Silkworm.� This
incident was the first time that a shipboard missile had killed a cruise
missile under combat conditions at sea.
On 4 June 1996,
the Asagira-class destroyer YUGIRI of the Japanese Maritime Self Defense
Force (JMSDF) accidentally shot down a U.S. Navy A-6 Intruder jet that was
towing a radar reflective target during joint gunnery exercises.� Both pilot and bombardier-navigator ejected
successfully.� The YUGIRI�s radar
locked onto the Intruder instead of the sleeve.� A post-accident review board� concluded that YUGIRI�s Phalanx was in
manual control and the YUGIRI�s gunnery officer gave the order to fire before
the A-6 was out of the CIWS engagement envelope.
These three
incidents are instructive in several respects.� First, CIWS does not work if it is OFF or
in STANDBY mode.� USS STARK found this
out with fatal results.�
Second, systems
do malfunction in combat situations and it is imperative to have backups in
place.� Sea Dart saved the day and
killed the inbound missile.�
Third, human
errors can lead to friendly fire incidents.�
When I was on USS HALSEY POWELL (DD-686) during an anti-air warfare
shoot in 1967, our Mk 37 director locked onto the the target sleeve�s tow
cable and began following it towards the target tug S-2E Tracker.� (Mk 37 director operators were warned about
this characteristic of the Mk 25 radar, but it happened anyway.)� The first indication was a direct hit about
half way between the target tug and the gunnery sleeve.� The 5-inch projectile explosion severed the
cable.� The tow plane immediately
signaled: �Cease fire.� Exercise over.�� The target tug returned to base with a
rather shaken aircrew.��
�
Above: Chinese �Silkworm� missiles being loaded aboard a fast attack craft (FAC) of the People�s Liberation Army-Navy (PLAN).� The missile is a copy of the Soviet SS-N-2 Styx.� The wings unfold when the missile leaves its launch tube.� The SS-N-2 is powered by an air-breathing turbojet engine and is boosted to flight speed by a disposable solid rocket booster.� (Photos: Chinese PLAN)���Phalanx
as a Land-Based Weapon System
The U.S.
Army�s version of CIWS is called C-RAM (Counter-Rocket, Artillery, and
Missile) system or the �Centurion�.�
First C-RAM units were deployed to Iraq in the summer of 2005.� C-RAM protects forward operating bases and
other high-value sites in and about Baghdad.�
C-RAM also deployed with British units around Basrah in the southern
part of Iraq.�� Like CIWS, C-RAM uses
the M61A1 20mm Gatling gun firing between 3,000 to 4,500 rounds per
minute.� By 2008, there were over 30
C-RAM systems protecting bases in the U.S. Central Command Area of
Operations.� A Raytheon spokesman told Navy
Times that 105 attacks had been defeated by the C-RAM system.� Another 23 C-RAM systems were on order for
Army use in September 2008. C-RAM does
not use the Mk 149 or Mk 244 rounds of the Navy�s CIWS.� Instead, C-RAM uses either the M246 HEIT-SD
(high explosive incendiary tracer, self-destroying) or M940 MPT-SD
(multi-purpose tracer, self-destroying) ammunition.� The self-destroying feature on tracer
burn-out prevents live ammunition from coming down on friendly areas and
personnel.� Above:
Raytheon C-RAM (aka �Centurion�) on its trailer� (Photo: Raytheon Company) � Operators
Specifications
(Block 1B)
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