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The Landing Craft Air Cushion (LCAC) is a class of air-cushion vehicle (hovercraft) used as landing craft by the United States Navy's Assault Craft Units and the Japan Maritime Self-Defense Force (JMSDF). They transport weapons systems, equipment, cargo and personnel of the assault elements of the Marine Air/Ground Task Force both from ship to shore and across the beach. ==Design and development== Concept design of the present day LCAC began in the early 1970s with the full-scale Amphibious Assault Landing Craft (AALC) test vehicle. During the advanced development stage, two prototypes were built. JEFF A was designed and built by Aerojet General in California, with four rotating ducted propellers. JEFF B was designed and built by Bell Aerospace in New Orleans, Louisiana. JEFF B had two ducted rear propellers similar to the proposed SK-10 which was derived from the previous Bell SK-5 / SR.N5 hovercraft tested in Vietnam. These two craft confirmed the technical feasibility and operational capability that ultimately led to the production of LCAC. JEFF B was selected as the design basis for today’s LCAC.〔(LCAC U.S. Navy Fact File )〕 The first 33 were included in the FY82-86 defense budgets, 15 in FY89, 12 each in FY90, FY91 and FY92, while seven were included in FY93. The first LCAC was delivered to the Navy in 1984 and Initial Operational Capability (IOC) was achieved in 1986. Approval for full production was granted in 1987. After an initial 15-craft competitive production contract was awarded to each of two companies, Textron Marine & Land Systems (TMLS) of New Orleans, La, and Avondale Gulfport Marine, TMLS was selected to build the remaining craft. A total of ninety-one LCAC have now been built. The final craft, LCAC 91, was delivered to the U.S. Navy in 2001. On June 29, 1987, LCAC was granted approval for full production. Forty-eight air-cushion landing craft were authorized and appropriated through FY 89. Lockheed Shipbuilding Company was competitively selected as a second source. The FY 1990 budget request included $219.3 million for nine craft. The FY 1991 request included full funding for 12 LCACs and advance procurement in support of the FY 1992 program (which was intended to be nine craft). The remaining 24 were funded in FY92.〔(Landing Craft, Air Cushion (LCAC), GlobalSecurity.org )〕 The LCAC first deployed in 1987 aboard USS Germantown (LSD-42). LCACs are transported in and operate from all the U.S. Navy's amphibious-well deck ships including LHA, LHD, LSD and LPD. Ships capable of carrying the LCAC include the ''Wasp'' (3), ''Tarawa'' (1), ''Anchorage'' (4), ''Austin'' (1), ''Whidbey Island'' (4-5), ''Harper's Ferry'' (2), and ''San Antonio'' (2) classes. All of the planned 91 craft have been delivered to the Navy. Of these 91 LCACs, seven of these have been disassembled for FGE, ten are in deep Reduced Operation Status (ROS), two are held for R&D, and 36 are in use on each coast at Little Creek, Virginia and Camp Pendleton, California. Eight minesweeping kits were acquired in 1994-1995. The craft operates with a crew of five. In addition to beach landing, LCAC provides personnel transport, evacuation support, lane breaching, mine countermeasure operations, and Marine and Special Warfare equipment delivery.〔 The four main engines are all used for lift and all used for main propulsion. The craft can continue to operate, at reduced capability, with two engines inoperable. They are interchangeable for redundancy. A transport model can seat 180 fully equipped troops.〔()〕 Cargo capacity is . The LCAC is capable of carrying a 60-ton payload (up to 75 tons in an overload condition), including one M-1 Abrams tank, at speeds over 40 knots. Fuel capacity is 5000 gallons. The LCAC uses an average of 1000 gallons per hour. Maneuvering considerations include requiring 500 yards or more to stop and 2000 yards or more turning radius. The bow ramp is wide while the stern ramp is wide. Noise and dust levels are high with this craft. If disabled the craft is difficult to tow. In recent years spray suppression has been added to the craft's skirt to reduce interference with driver's vision. The LCAC is a dramatic innovation in modern amphibious warfare technology. It provides the capability to launch amphibious assaults from points over the horizon (OTH) from up to 50 nautical miles offshore, thereby decreasing risk to ships and personnel and generating greater uncertainty in the enemy's mind as to the location and timing of an assault, thereby maximizing its prospects of success. The LCAC propulsion system makes it less susceptible to mines than other assault craft or vehicles. Due to its tremendous over-the-beach capability, the LCAC can access more than 80% of the world's coastlines. Previously, landing craft had a top speed of approximately eight knots and could cross only 17% of the world's beach area. Assaults were made from one to two miles off-shore.Its high speed complements a joint assault with helicopters, so personnel and equipment can be unloaded beyond the beach in secure landing areas. For 20 years, helicopters have provided the partial capability to launch OTH amphibious assaults. Now, with LCAC, landing craft complement helos in speed, tactical surprise and without exposing ships to enemy fire.〔 The similarities between a Navy LCAC and an airplane are substantial. The craftmaster sits in a "cockpit" or command module with a headset radio on. He talks to air traffic control which for LCAC's is well-deck control located near a ship's sterngate. The ride feels like a plane in high turbulence. The craftmaster steers with a yoke, his feet are on rudder controls—and he flies a lot like a hockey puck on an air hockey table, The LCAC is similar to a helicopter in that it has six dimensions of motion. Operating the LCAC demands unique perceptual and psychomotor skills. In addition, with a machine as expensive and inherently dangerous as the LCAC, sound judgment and decision-making also play an important role. Concerns over escalating training cost, projections for an increased number of LCAC vehicles and crew, and a high attrition rate in training highlighted the importance of developing a more accurate means of selecting candidates. Attrition of operators and engineers has dropped from an initial high of 40% in 1988 to approximately 10-15% today.〔 In Fiscal Year 2000 the Navy started an LCAC Service Life Extension Program (SLEP) to add 10 years of design life to each craft. The SLEP will be applied to 72 LCACs, extending their service life from 20 to 30 years, delaying the need to replace these versatile craft.〔〔(Surface Connector Outlook, N954 Expeditionary Preposition/Connector Branch, September 2012, CAPT Sean Geaney USN )〕 Without a SLEP the first LCAC would face retirement in 2004, based on a 20-year lifespan. Naval Sea Systems Command (NAVSEA) has been working with Textron Marine and Land Systems since April 1996 on LCAC SLEP research and development. The actual SLEP modifications are planned to be conducted in two phases. Phase I. Over a period of several years electronics system recapitalization will take place at each Assault Craft Unit (ACU), where the craft are physically located. This will involve replacing current electronics components, which are increasingly becoming obsolete and unsupportable, with an open electronics architecture using easily upgraded, Commercial Off-The-Shelf (COTS) components. The new electronics suite will be more reliable and less costly to operate and maintain. Phase II. Buoyancy box replacement will be conducted at the Textron Marine and Land Systems facility in New Orleans, LA, where Textron will use design changes, coatings, and changes in materials to increase the LCACs resistance to corrosion. Phase II will also include the electronics upgrade of Phase I, until the entire active fleet is outfitted with the new configuration. The new buoyancy box will incorporate improvements to damage stability and trim control of the LCACs. NAVSEA transitioned from the research and development effort to the SLEP in 1999. Concurrently NAVSEA also considered additional SLEP options, including an enhanced engine to provide improved operation in excessively hot environments and an advanced skirt that is more reliable and cost effective.. The Navy continued the LCAC Service Life Extension Program in Fiscal Year 2001. This program combines major structural improvements with Command, Control, Communications, Computer and Navigation upgrades and adds 10 years to the service life, extending it to 30 years. In FY 2001, it was funded at $19.9 million and extended the service life of 1 craft. The SLEP is planned for a total of 72 craft. The near-term focus will be on the "C4N" (Control, Communications, Computers, and Navigation ) program, to replace the crafts' obsolete equipment. This will focus on replacement of LN-66 radars with modern, high-power P-80 radar systems. Additionally, the SLEP will include an open-architecture concept, relying on modern commercial-off-the-shelf (COTS) equipment, which will allow much easier incorporation of later technology changes, such as the precision navigation system and communications systems ¾ fully interoperable with in-service and near-term future Joint systems ¾ now planned. The C4N program is to complete by 2010. Through 2016, the Navy will look to incorporate other important service-life enhancements: Engine upgrades (ETF-40B configuration) that will provide additional power and lift particular in hot (110-degrees F and higher) environments, reduced fuel consumption, reduced maintenance needs, and reduced lift footprint; Replacement of the buoyancy box to solve corrosion problems, incorporate hull improvements, and "reset" the fatigue-limit "clock"; Incorporation of a new (deep) skirt that will reduce drag, increase performance envelope over water and land, and reduce maintenance requirements.〔 As of September 2012, there are 80 LCACs in the U.S. Navy inventory, and 39 of these LCACs have undergone the SLEP conversion, 7 more SLEP conversions are in progress and 4 are awaiting induction. The FY 2013 budget authorizes 4 SLEP conversions per year through to FY 2018. The last of the 72 SLEP conversions will be delivered to the Navy in Fiscal Year 2020. A number of LCACs are currently under development and testing at the Naval Support Activity Panama City in Panama City, Florida. As the first SLEP LCAC reaches its 30 years of design service in 2015, they will gradually be retired. In 2019, at which point the inventory of LCACs will have fallen to 50, the USN begin receiving the new Ship-to-Shore Connector (SSC), the LCAC-100.〔 The USN inventory of LCACs will continue to fall, as the SLEP LCACs are retired, until 2023 when the inventory will reach a low of 40 SLEP LCACs and SSC LCAC-100s. The inventory will remain at 40 until 2026 when the production of SSC LCAC-100s will begin to outnumber the retirement of SLEP LCACs. Current projections foresee the inventory rising to 60 SSC LCAC-100s in 2031 and 72 SSC LCAC-100s on 2034.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Landing Craft Air Cushion」の詳細全文を読む スポンサード リンク
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