MK 41 VERTICAL LAUNCHING SYSTEM FLEET APPLICATION

CAPT. JAMES J. KULESZ, USN

MK 41 VERTICAL LA UNCHING SYSTEM FLEET APPLICATION

THE AUTHOR

b currently program manager for the MK 41 vertical launching system (PMS 410). A native of Pittsburgh, Pa, he w m commissioned in June 1961 at the United States Naval Academy.

After serving as missile handling and third divirrion officer on the USS Little Rock until September 1963, he attended the United States Naval Destroyer School. In August 1945 he w m e d duties m weapons officer for USS De Haven.

Captain Kulesz received the degree of master of science in electrical engineering in 1969 from the Naval Postgraduate School in Monterey and b a graduate of the command and staff course at the Naval War College of the National War College of the Republic of Germany.

He served as commanding officer on the USS Conflict and m deputy combat systems engineer for the AEGIS project at Naval Sea Systems Command.

Prior to assignment as program manager at PMS 410, Cap- tain Kulesz was the AEGIS department head at the Naval Ship Weapons Systems Engineering Station, Pt. Hueneme.

ABSTRACT

The unique physical construction and launch control system architecture of the MK 41 vertical launching system (VLS) makes it particularly adaptable to a variety of missiles and ship classes. The U.S. Navy began installing the MK 41 VLS in deep draft combatants early this year.

System attributes such as increased firepower, reduced manning and training requirements, high reliability and low main- tainabTty indicate the MK 41 will best answer the fleet’s re- quirement for highly capable launchers at minimum life cycle cost. Several launcher variants can be readily configured from MK 41 launcher components. Two lengths have been developed and proved during land based and at-sea tests. These MK 41 derivatives retain all the benefits of the VLS while permitting a tailored defense capabTty throughout the surface fleet.

INTRODUCTION

T h e multimode MK 41 vertical launching system (VLS) was designed and developed as an alternative to single purpose, single and dual-rail launching systems and greatly simplifies missile system integration in Navy ships. The MK 41 meets the Navy’s need for increased firepower, availability, reliability, flexibility and reduced manning at affordable costs.

The transition from prototype research and development to production has been completed. Two MK 41 launchers have been landed in USS Bunker Hill (CG-52). Subsequent launchers will be installed on the remainder of the Ticonderoga class cruisers. The DD-%3 Spruance class and the DDG-51 Arleigh Burke class destroyers are scheduled for MK 41 launchers in the near future.

174 Naval Engineers Journal, May 1985

The system design and architecture has resulted in a launcher characterized by modularity, reliability and multiple warfare capability. The flexibility of the MK 41 design permits offensive and defensive ordnance application in a single launcher and provides adaptability to future surface warfare threat driven requirements. (Figure 1)

Until the MK 41 was developed, Navy launching systems were single or dual-rail pointing mechanisms characterized by thousands of discrete moving parts. Such systems required substantial manning for maintenance and were l i i t e d in firing rate if either rail or rail loading casualties occurred or ordnance changes were required. Launchers were located above deck with attendant possibilities of both combat and environ- mental damage. Magazines were below deck with large mechanical rotating machinery. Reload missiles aboard the combatants were housed outside of containers and downloaded into magazines with attendant environ- mental exposure and chance of damage.

With the MK 41, the launcher and magazine are located below deck beneath armored hatches with all missiles vertically positioned on a rail in corrugated steel canisters ready to fire. The missile canister serves as a shipping container and launch rail.

The positioning of each missile on an individual launch rail increases the packing density in the magazine and eliminates the complex and failure-prone positioning machinery previously needed to bring different missile rounds to a firing rail.

The inclusion of the canistered rounds in units of eight in the MK 41 launcher modules produces an architecture that allows the launcher capacity and launcher length to be tailored to the ship’s geometry and mission requirements.

DESIGN CONCEPT

In the late 7Os, air defense elements of the battle group began to focus on the limitations imposed by missile launchers. The defensive detection and asset management capabilities offered by the AEGIS system more than equaled the near term threat projections and with improved launcher performance can easily extend that advantage into and beyond the next decade.

The two factors which drove the VLS design were performance and affordability.

PERFORMANCE CONSIDERATIONS

The ability to counter a eoordinated saturation attack required a reliable rapid fire, multimode, high capacity launcher capability. Multimode capability refers to the

KULESZ MK 41 VERTICAL LAUNCHING SYSTEM

TWO LAUNCH CONTROL UNITS

MK 13 MOD 0

MODULE

ADAPTER

STRl KEDOWN MODULE

w MAGAZINE

Figure 1. System overview

ability to simultaneously support launching of missiles in S U D D O ~ ~ of AAW. ASW and SUW/STW warfare

AFFORDABILITY

areas: -Several major- VLS design requirements were derived from this top level view:

Large Missile Capacity Module Configuration

Four square cells separated by long narrow uptake

Narrow maintenance access aisles hatch

Rapid Fire

Electronic vs. mechanical launcher operations Independentlparallel missile access Hatches begin opening during missile preparation

Reliable

Static structure vs. moving articulating mechanisms Replication of a few simple parts Redundance Separate opening hatch for each missile cell which does not block any other cell

Multimode

Simultaneous interface with all warfare areas Any missile type in any cell location

The primary features that minimize the acquisition and life cycle costs of the VLS are:

Reduced acquisition costs. The elimination of the large, precision, rotating machinery required in the rail launcher magazines and the increased packing fraction of missiles in the modular VLS magazine re- duces the cost of the MK 41 launcher mechanism 112 that of the dual-rail launchers based on cost per missile launched. Reduced manning. The biggest single cost in the life cycle after acquisition is manning with its inherent training, replacement and habitability impacts. The greatly increased mean time between failures (MTBF) of the MK 41 systems allows shipboard dedicated per- sonnel to decrease by a factor of two. Launcher- dedicated manning on the two-launcher MK 41 ship- set in USS Bunker Hill (CG-52) is 4 GMMs compared with 17 on the MK Zbequipped Ticonderoga.

Secondary but still significant benefits result from both the reduced cost of and the reduced need for spares. Additional cost savings are associated with the multimode capability in which one launcher can simultaneously support three warfare areas. Other areas where saviigs accrue are in a decrease in missile damage as a result of them being protected by canisters and the


MK 41 VERTICAL LAUNCHING SYSTEM KULESZ

increase in missile reliability through constant encap- sulization.

REQUIREMENTS THROUGH DEVELOPMENT

Missile requirements drove the launcher design. With increasingly complex warfare threats directed at modern combatants and the expected increase in the intensity of such threats, response time was also determined to be a critical feature in launcher design. It was determined that in deep draft combatants a maximum magazine loadout of multiple warfare missiles was essential to mission success.

The MK 41 was designed as a modular system to fire multiple types of missiles from corrugated steel canisters vertically positioned and ready to fire from launcher cells. Such canisters serve as shipping, storage and firing containers for individual missiles. This design feature minimizes ordnance handling since missiles are loaded at weapons stations as wooden rounds, shipped to combatants and loaded into the MK 41. Any canistered missile can be fired from any launcher cell. A key safety feature in the system design was that, while in the launcher, the missile is maintained 100% deadfaced until se- lected for launch and each is protected by an individual deluge system.

Elimination of all single points of failure was a design goal. The hot launch from the magazine created the first major technical challenge of how to safely handle gas management and vent missile exhaust to the atmosphere. Figure 2 illustrates the solution of venting the missile exhaust into an ablative-lined plenum and uptakes into the atmosphere.

This concept has been throughly tested in over 40 firings from the launcher at White Sands Missile Range (WSMR) Pacific Missile Test Center (PMTC) and China Lake. Firings were made from a single launcher module and from the two-module magazine in USS Norton Sound. Missiles fired included Standard I and 11, Tomahawk and ASROC. All tests proved that the ablative-lined gas management system safely and re- liably vents the exhaust gases. A test at WSMR also showed that the launcher was capable as designed to safely handle a restrained firing should such an event occur. Each canister contains an internal deluge system that is connected during strikedown to the ship’s fire- main. Upon detection of a potential hazard (either a restrained firing or an overtemperature condition) the deluge is activated and the missile warhead cooled. Both ablative-liner and deluge systems proved in the tests are built into each launcher module. Development tests also indicated no damage or loss in effectiveness to missiles as they traveled through their own plume.

Clustered vertically positioned missiles of the MK 41 offered an immediate increase in magazine capacity from 44 to 61. Two canister sizes enable incorporation of missiles from 144 in to 256 in by simply using an adapter section to make up a uniform stack height.

A 61-cell magazine in USS Bunker Hill is configured from seven eight-cell modules and one five-cell module. The five-cell module, with a strikedown crane in the


Figure 2. Gas management system

space normally occupied by three cells, allows underway replenishment at sea.

Since each module is an independent launcher with its own independent launch electronics and gas management system, the system can be placed on a number of ship classes tailored to space that is available. The DD-963 class will carry one 61-missile MK 41 magazine forward and the DDG-51 one 61-missile magazine aft and a 29-missile magazine forward.

The MK 41 system reliability was assured by another key design feature. All of the moving parts are centered in the top deck and hatch assembly, and individual elec- tric motors open and close each hatch. This ensures that no moving part can hold more than one missile in a cell. Unlike rail launchers this is the only mechanical operation required to launch.

Providing this benefit was the storage of each missile behind a separate hatch on launch rails built into the canister. The only moving parts of the launcher are the hatches and their link mechanisms. The maximum mechanical load is the 3.5 Hp required to rapidly open the armored hatch. The rocket motor of the missile gives energy for the movement of the missile from the stored vertical position to deck height and finally flight velocity.

The system’s designed-in redundancy with intercon- nected launch control units programmed to reselect a new missile if problems are encountered at launch fur- ther minimizes the chance of a single point failure. Built-in test equipment which recycles automatically maintains an up-to-date status on all launcher cells.


System modularity illustrated in Figure 3 makes it easier to install the MK 41 and minimizes dockside time both for new construction application and backfitting into existing ships. Fault isolation is aided by built-in test features and the MK 41 remove and replace repair philosophy.

All features of the MK 41 were aimed at elimination of a sequential fault failure mode. This goal has been at- tained. The only fault that will prevent missile launch is total loss of ship’s power. This benefit is achieved through the combination of launcher architecture and component reliability. The architecture features include redundancy of the launch control units, power supplies and microswitches, the separation and partitioning of the gas management system, sprinklers, deluge and communication subsystems, and the parallel placement of missile launch rails, firing circuits and built-in test sensors.

SYSTEM DESCRIPTION

A MK 41 magazine is composed of replicated modules that group together to form the launcher and complete the magazine ballistic protection belt at the weather deck. Each module is a separate launcher structure capable of firing eight canistered missiles. All launch control functions requiring electrical power, gas management, communication, damage control, and lighting systems are contained within the module.

High system reliability is obtained by redundant cir- cuitry, reduction of moving parts and elimination of single point failures by design. These factors contribute to a lower lifetime support cost by a reduction of scheduled maintenance and manning requirements compared to traditional launchers.

Figure 3. System modularity

DECK AND HATCH

DELUGE SYSTEM

UPTAKES

OUTBOARD STRUCTURE

PLENUM

DRAIN SYSTEM

Figure 4. Eight-cell module

MODULE

An eight-cell module is the unit replicated to form a launcher magazine. Each module consists of structure, deck, hatches, launch sequencer, motor control panel, cabling, power supply sets, and walkways, and is completed as a unit ready for installation aboard ship. (Figure 4).

The module structure forms the eight cells into which the canistered missiles are loaded, supports the armored deck, and provides a support for mounting electrical equipment.

For gas management each module contains a plenum and uptake to vent the exhaust gases from a fired missile. The plenum and uptake are lined with ablative material to protect the structure against the missile exhaust.

A deluge system, with individual valves for each canister, provides water deluge to the particular missile warhead in the event of overheating or accidental motor ignition. Tests have shown that a module can survive a full duration restrained firing while this system cools the warhead.

In addition, the launcher plenum base and uptakes which form the heart of the gas management system are fabricated as separate bolted-together units. These mechanical features allow for relatively easy sealing of the total launcher length and provide a volume for ex- pansion for missile gases to direct them vertically to the atmosphere through an armored hatch.

The module top deck and hatch assembly provides a weather seal and ballistic protection equivalent to 3/4 inch HY-80 steel to the launcher structure beneath, and



Figure 5. MK 13 canister


MK 13 SM2

MK 14 TOMAHAWK

MK 15 ASROC


supports the armored cell, uptake hatches and associated mechanisms, An outboard steel lattice work sup-

ports the deck assembly, provides a structure to mount the module electronics, and forms the eight cell loca- tions for canister insertion and storage.

DECK AND HATCH

LAUNCH SEQUENCER

MOTOR CONTROL PANEL

UPTAKES

Figure 8. Strikedown module


The missile canister is sealed at the weapons station by forward “fly through” and aft “blow out” covers. Seals are provided at each end, at the interfaces between the canister and the plenum, to preclude rocket motor exhaust from entering the magazine space. The internal fittings, safe and arm devices and restraint mechanism adapt unique missile characteristics to the canister. The canister serves to store, package, transport and launch the missile.

As noted, system safety in the event of an inadvertent firing of a rocket motor due to external heat sources is provided by a deluge system. The deluge system acti- vates spray nozzles positioned on the canister to provide cooling water to the missile warhead when a hazard is detected.

Three canisters currently exist for the MK 41 launcher. The MK 13 and 15 are 228” long and are configured internally to accommodate the Standard missile and vertical launch ASROC. (Figures 5 and 6) The MK 14 is 264“ long and contains the Tomahawk missile variants. This canister is shown in Figure 7. The canisters are qualified for all the shipping and launch environments and are designed for up to three-high stacking in the replenishment ship magazines. CONREP and VER- TREP operations on a Spruance class ship and strike-


Figure 9. Strikedown operation

down operations on USS Norton Sound have demonstrated the canisters’ versatility and ability to protect the missile. The missiles are loaded into the canisters at weapon loading stations. Naval Weapon Station, Seal Beach is presently starting canister loading qualification for USS Bunker Hill. NWHS Yorktown will be brought on line in July 1985.

CANISTER STRIKEDOWN

The strikedown module, (Figure 8) is identical to the eight-cell module except for the integral strikedown system which occupies the space of three missile cells. The strikedown system consists of an extendable hydraulic crane stored beneath an armored hatch below deck on a hydraulic elevator. A self-contained hydraulic system operates both the elevator and the crane. The crane is elevated to deck level and deployed for strikedown operations. The system is designed to provide positive control of the canistered missiles in sea states up to 5. Sustained strikedown rates of 4 per hour were demonstrated aboard USS Norton Sound. The strikedown operation is illustrated in Figure 9.

LAUNCHER ELECTRONICS

The launcher communicates to the ship’s combat system by a digital Link to two U.S. Navy standard mini- computers, (AN/UYK-20). These two launch control units (LCUs), with accompanying teletype and magnetic tape-drive input and output peripherals are located out of the magazine with the ship’s other combat system computers. Each of the two LCUs is completely redundant and able to control all missiles in both magazines. Normal operation is for each LCU to share the inventory, with a single LCU communicating to half the missiles in each magazine. In a casualty mode, one LCU can take over the entire inventory and continue launches without interruption.

The launch control system (LCS), is a command and response system with each LCU able to accept commands from the ship’s AAW, SUW, and ASW weapons control system (WCS). Logic resides in the LCU com-

puter programs to allow the ship to assign launch control priority to any of the WCSs.

In Condition I11 steaming, the LCU keeps the launcher in standby mode with the power ON and a continuous series of BITE (built-in test equipment) and inventory reporting cycles being conducted. Missile inventory is reported to the ship’s WCS each time the launcher is powered up, upon request, or if a change in status oc- curs. A BITE cycle is conducted every two hours with any failures being reported to WCS along with a failure descriptor to assist maintenance. The magazine is unmanned at all times, except during strikedown operations or maintenance activity.

The launch control system provides three modes of operation.

Standby - All equipment is on-line; normal BITE cycles are performed; missile round inventory is reported and both missile selection and launch circuits are inhibited. Simulation - All equipment is on-line; VLS provides nominal responses to WCS select and launch orders, while maintaining the launch circuits deactivated. This mode is specifically provided for crew training. Ready Alert - All equipment is on-line and missile select and launch orders are executed. The launch control units are completely redundant, which provides full operation of the launcher by either unit. When both units are operating normally, each communicates with all modules and each controls half the modules in each magazine. If one LCU is in a casualty mode, there is no loss of the number of missiles available and no degradation in launcher performance.

A launch sequencer housed on each module provides launch control for the missiles in the module by prepar- ing the missiles for launch, providing commands to the motor control panel (MCP), and controlling the module deluge system and built-in test equipment. A MCP and power supplies are also part of each module. The MCP distributes power to the module, controls the cell and uptake hatches and the plenum drain valve, and interfaces with the status panel.

A status panel, located outside each magazine entry, monitors hazards and continuous power interrupts, controls magazine power, enables strikedown and anti- icing, and provides the magazine interface to damage control central. It also provides a hard-wire launch-enable interrupt so that missiles cannot be launched when the magazine is occupied for maintenance or strikedown operations.

SYSTEM OPERATION

The unmanned MK 41 system operates in three command modes: standby, ready alert, and simulation. The standby mode is the long term operating mode during which all equipment is energized and periodically tested using built-in test features, with missile firing inhibited when ordered by the weapon control system (WCS). Transition from one mode to another mode is accom- plished in milliseconds. A typical target engagement



TABLE 1. Features to Maximize Missile Availability

REDUNDANT WCS INTERFACES 0 MAGAZINE POWER

- LAUNCHER CONTROL AVAILABLE TO A L L WCS ON A PRIORITY BASIS

- ONE WCS INTERFACE TO EACH LCU

- NORMAL AND ALTERNATE POWER

- REMOTE AND BACK-UP CONTROL

REDUNDANT LAUNCH CONTROL UNITS 0 MODULES INDEPENDENT WITHIN MAGAZINE

- NORMAL AND ALTERNATE POWER - SEPARATE GAS MANAGEMENT SYSTEMS

- SEPARATE ELECTRONICS SET - LCU CASUALTY OPERATION WITH NO

LOSS I N PERFORMANCE

- AUTOMATIC RECONFIGURATION FOR - FAILURE I N ONE DOES NOT AFFECT COMMUNICATION FAILURES OTHER MODULES

- LAUNCH CONTINUATION DURING 0 EIGHT MISSILES PER MODULE CASUALTY SWITCH

- INDIVIDUAL CELL HATCHES

- CANISTER FLY-THROUGH/BLOWOUT COVER - AUTOMATIC RECOVERY FOR POWER

SWITCHOVE R

- REDUNDANT LCU TO LSEQ INTERFACE

- EITHER LCU HAS ACCESS TO EACH LSEQ

FAILURE OF ONE CELL DOES NOT AFFECT OTHER CELLS IN MODULE

0 HALF-MODULE PARTITIONING

- PORTiSTARBOARD CABLE RUNS - POWER SUPPLIES

- CELL HATCH CONTROLLERS

- FAILURE IN ONE HALF MODULE (4 CELLS) DOES NOT EFFECT OTHER HALF MODULE

would be initiated by an order to bring the launcher from standby to the ready alert condition, indicating a hostile track. When the WCS obtains a valid fire control solution, a “missile select” order is issued to the VLS. Upon receipt of this order, the launch control system (LCS) selects the appropriate module and cell, applies missile warm-up power, initiates actions to open cell and uptake hatches, and releases the missile restraint in the canister to the fly through position. Upon successful reporting of these mechanical actions, the LCS, upon command from the WCS, initiates the nonreversible battery activate command, routes the WCS-generated missile guidance data to the missile, and completes the remaining missile functions to effect launch. Upon in- itial missile movement, the electrical circuits to the cell are isolated and a “missile away” timing signal is sent to the WCS for missile acquisition purposes. After an appropriate time for missile flyout, the hatches are clos- ed to complete the launch sequence.

Each launcher module is designed to simultaneously prep and launch two missiles of any type. In a MK 41 eight-module magazine, 16 missiles can be prepped for rapid fire. For a double ended ship, such as USS Bunker Hill, 32 missiles out of a total possible load of 122 can


be in prep. Since each missile type has different preparation and initialization times, provisions must be made to select between missile types if battle conditions warrant. Features that maximize missile availability are contained in Table 1.

The MK 41 allows for the interruption and fire thru of SM 11s during a preparation of Tomahawks to ensure a quick reaction AAW mode. This feature establishes the enormous superiority of the VLS system over rail launchers.

System safety features and benefits have been re- tained throughout extensive upgrading and testing. Features incorporated into the design preclude the possibility of an inadvertent launch or a dangerous flyout condition. Independent of the numerous logic checks implemented in the system is a special hard-wired signal “launch enable,” controlled by a key switch in the ship’s combat information center (CJC). This signal provides an interlock of all critical missile functions independent of all computer programs (Table 2).

All data transmitted to and within the launcher are subjected to validity tests. All launcher commands are automatically tested for applicability to the launcher mode, and, if launch related, are also checked for cor-


ssw +-- AAW e- ASW +-

AAW &-- ssw t- ASW +--

TABLE 2. Launch Enable

0 PURPOSE

- PROVIDE A POSITIVE LAUNCHER INTERLOCK INDEPENDENT OF COMPUTER PROGRAM

0 CONTROL TECHNIQUE

- LOCAL ACTIVATED AT MAGAZINE STATUS PANEL

- REMOTE ACTIVATED IN SHIP'S COMBAT INFORMATION CENTER

0 IMPLEMENTATION

- ACTIVATED MANUALLY

- ISSUED PRIOR TO MODE CHANGE TO READY ALERT IF MISSILE LAUNCH IS INTENDED

- INTERRUPTS CRITICAL FUNCTION RELAYKIRCUITS

TO AFT MAGAZINE MODULES LSEQs

+ l MAG AZ IN E

I FROM/TO ' LCUS

1 a

t I

MODULE I

I I I LSEO I I I I ' TO I

I I I LSEQs

MAGAZINE I I

1

LAUNCH

UNIT

TOFWD

l I

I

I 1 ' I

8

1 60Hz 1 a CELLS -

1 MODULE 1 4 PLENUM I I MCP'S I

4 8 MODULE 2

I TOMODULE TO SHIP PWR

CONTROL PANEL DAMAGE STATUS 1 DlST

PANELS

I . 1

I

I I I I

I I 1

I 1 8 LSEOS I MAGAZINE I I I I I I I

- I

MODULE 3

400 Hz

I

I

I I ' TO I MODULE

LAUNCH

UNIT

TOFWD

MODULE 8 1 8

TO AFT MAGAZINE MODULES LSEQs VERTICAL LAUNCH - LAUNCH CONTROL SYSTEM

~ _ _ _ _

rect sequence, canistered missile type, and address. Prior to a "missile select" order, the missiles are electrically disconnected and surrounded by a continuous radio frequency shield. The launch logic ensures that nonreversible missile functions do not occur until after module/canister mechanical functions have indicated first motion. Prior to igniting the rocket motor, two independent monitors must indicate that the armored hatches are fully open, and that the missile restraint has been released. Extensive hazard analysis, fault tree analysis, and failure modes and effects analysis have been conducted and have formed the basis for the launcher system safety design. These analyses have also addressed the extensive logic necessary to provide correct and safe operation for possible default condi-

tions and, in particular, safing procedures for missile misfire/dud situations.

ADVANCED CONCEPTS FOR FUTURE FLEET APPLICATION

The MK 41 VLS will undoubtedly serve the U.S. Navy for many decades; therefore, it is imperative that this concept be examined for adaptability to future missiles, fire control systems and hull shapes. The MK 41 flexibility and adaptability is critical for such configurations to be effectively utilized and survive.

Fortunately, the features that provide the high reliability also provide the adaptability to ensure growth as combat system requirements change. The continuing demand for rapid and more capable self defense systems, and the extension of this battle space beyond the current limits of area defense are two trends evident in maritime combat system needs. Such trends are con- sequences of increased Eastern Bloc saturation attack capabilities, the need to reach out and stop the Backfire, SUAWACS and jamming aircraft as well as defense leakers need to be halted before the weapon release.

The VLS is ideally configured to provide orderly growth to a series of variants that provide a spectrum of long term capability in sync with combat system needs. The VLS can readily be tailored in both capacities, missile type and magazine size to fit the changing needs of both the U.S. and NATO navies. Since the interface between the launcher and the ships weapon control systems is already digital (Figure 10) with no analog inputs, adaptation to fire control changes is bounded only by

WEAPON CONTROL SYSTEMS

WEAPON CONTROL SYSTEMS

Figure 10. LCU system block diagram

Naval Engineers Journal, May 1985 181


Figure 11. VLA modifications

computer program changes. In fact, the first of these adaptions is currently underway in the change to AN/UYK 44s and 43s in the Arleigh Burke (DDG-51). Adaption to new missile types is illustrated by the recent incorporation of VLA into the MK 41 for CG-57 and up. (Figure 11). In this case the change was limited to six cards in the launch sequencer unit and the interfaces of the canister (changing a MK 13 to a MK 15). Manning, training, recruiting costs did not change. A similar change is envisioned for the sure to come ASAM missiles which will be used to extend air battle space out to the Soviet launch platforms.

Such changes are incorporated into the present MK 41 without a change in launcher size. An adaption of another type is illustrated by the change in magazine size for the Arleigh Burke class destroyer in which four modules are grouped forward on the ship to provide a 29-missile magazine. Adaption in launcher length, to fit either a different missile load out mix or to adapt to specific hull configuration is also possible. The MK 41 can exist in either the “strike” length Tomahawk- capable version now in production for the Bunker Hill, Spruance and Burke class ships or as a “tactical” version. This configuration was fabricated and opera- tionally qualified aboard USS Norton Sound in 1981


and is capable of handling all the present AAW and ASW weapons. This variant was lengthened three feet to become the MK 41 strike launcher. A third variant 16.5 feet long would be tailored to the requirements for self defense or secondary battery. A new canister length would be required and would be sized to accommodate the 12-foot family of missiles that bounds all self defense/point defense rounds. In such launchers, two types to magazine densities are possible. Rounds with folding fins (AMMRAM) in a cluster of four housed in a 25-inch square canister gives a single eight-cell module a 32-round capacity. Three launcher lengths are illustrated in Figure 12.

Nonfolding or semispan folded missile configurations neatly fit one in a canister. The unique fabrication features all moving parts in a “top deck assembly” with a gas management system plenum as a separate assembly spaced from the deck by segmented uptakes. Current power supply capacity and voltage ranges are con- sidered sufficient for integration of future missile requirements. Each variant differs but retains the solid engineering, test and operational experience of all others. In all, every moving part and spares and lowest repair- able units (LRUs) are 100% common as are 94% and 85% respectively of all parts training and technical


MK 41 STRIKE TACTICAL SELF-DEFENSE LAUNCHER LAUNCHER LAUNCHER

Figure 12. Three launcher lengths are available

manuals. The beneficial effect on life cycle cost of being able to satisfy all launcher needs with this one launcher family should not be overlooked.

In the high-performance stable platforms of surface effect ships and hydrofoils, the relatively lightweight and modular VLS can offer a more streamlined ap- proach to launcher installation than conventional launchers. Since the system is modular, it can be accommo- dated within available space and provide multiple type missile launching capability in one launcher. Omnidirec- tional, the MK 41 has no blind firing zones caused by a ship’s superstructure.

The flexibility of VLS to monohull designs has been demonstrated. Applying VLS design concepts to advanced hulls may well be the next challenge. Since the FFX exploratory design project in NAVSEA is consid- ering both the monohull and SWATH configuration for an ASW frigate, it may be beneficial to consider VLS application in a SWATH hull.

The SWATH hull form would allow the VLS to exhaust missile gases downward into the air gap beneath the bridge structure and between the hull struts as illustrated in Figure 13. Alternatives to the gas management system associated with VLS are possible. Invest- ment already made in engineering development and test can be used even if the gas management system and out-

\ \

Figure 13. SWATH hull

Naval Engineers Journal, May 1985 183


board structure required by monohull ships is not. In- vestment in both electronics and the canisters can be effectively used. For surface effect ships, air cushion vehicles and SWATH ships the possibility exists of ex- hausting the rocket motor gases directly between the hulls. Such advanced ship design application should re- duce VLS cost and improve system performance by providing stabilized hulls less vulnerable to shock. The modular concept of VLS provides the hull designer with

an opportunity to arrange in-line or in clusters, as appropriate.

The VLS is a flexible system with demonstrated attributes and operational benefits, desirable to improve combat effectiveness throughout the fleet. The application of VLS and its derivatives will simplify training and support and make maximum use of manpower and equipment resources if deployed as a standard system throughout the fleet.


Documents

MK 41 VERTICAL LAUNCHING SYSTEM FLEET APPLICATION