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XOH-1 (OH-X) New Observation Helicopter / AH-2

Kawasaki designed Japan's first indigenously developed helicopter, the less than successful OH-1 [ex XOH-1 and OH-X), unofficially nicknamed Ninja. Like similar types, Japan's new indigenous battlefield scout helicopter has tandem seating and stub wings for armament. The ducted tail rotor is of "fenestron" type. The design features a composite hinge-less rotor hub for high control responsibility with damage tolerant main rotor blades, and auto Flight Control System. The targeting system is integrated, with FLIR, TV and LASER ranging system. The shock absorbing seat and crew protection armor are part of the integrated cockpit.

Kawasaki Heavy Industries, Ltd. had been developing an all-composite bearingless helicopter main rotor system for over fifteen years. The bearing-less rotor system consists of a hub plate, torsion elements and the main rotor blades. These components are very complex composite parts, requiring an innovative automated lay-up and molding process. To facilitate this need KHI developed a robotic roving placement system and a new molding process called Matched-die Isostatic Pressing, MIP.

One JDA project to which the aircraft industry's fortunes are tied is the OH-X observation helicopter, the first such aircraft, including engine, to be developed in Japan. KHI is the airframe prime contractor, just as it is on the McDonnell Douglas-licensed OH-6D, which the OH-X would replace. MHI is in charge of the new helicopter's twin engines.

The Japan Defence Agency (IDA) awarded Y2.7 billion (US$22.5 million) in FY92 to cover the basic design phase of a helicopter to replace OH-6Ds of JGSDF, then provisionally designated OH-X. RFPs issued by JDA's Technical Research & Development Institute (TRDI) on 17 April 1992. Kawasaki was selected as prime contractor (60% of program) 18 September 1992, with Fuji and Mitsubishi (20% each) as partners. The Observation Helicopter Engineering Team (OHCET), formed by these three companies, began preliminary design phase 1 October 1992. Mockup made public 2 September 1994 under Japanese name Kogata Kansoku (new small observation [helicopter]).

The program initially included six prototypes (four flying, two for ground test). A total of four were delivered between May and August 1997. The first aircraft (32001) was rolled out at Gifu on 15 March 1996 and made its first flight 6 August 1996, followed by second prototype on 12 November. The OH-1 designation was assigned late in 1996. The first two XOH-ls were handed over to JDA on 26 May and 6 June 1997. A third was first flown on 9 January 1997, at which time earlier aircraft had accumulated some 30 and 20 hours, respectively; and handed over 24 June 1997. The fourth was first flown on 12 February 1997 and handed over 29 August 1997. Prototypes renumbered by 1999 from 32001-04 to 32601-04.

First three production OH-1s funded FY97 and ordered 1998; first prototype flown with more fuel-efficient TS1-10QT (replacing XTS1-10) engines, 30 March 1998. By early 1999, four prototypes had flown 450 hours and were due to complete further 450 hours by end of 1999, including operational evaluation at Akeno JGSDF base. First production OH-1 (32605) flown July 1999 and handed over to JGSDF at Gifu 24 January 2000.

In early 2007 Kawasaki Heavy Industries (KHI) prepared an upgrade plan for its OH-1 scout, which the company planned to offer to meet a JGSDF requirement for 120 utility helicopters. Western manufacturers had urged consideration of local production of the AgustaWestland AW139 or Bell 412. KHI could team with AgustaWestland to offer the AW139, and Fuji Heavy Industries with Bell on the 412, but the government was leaning towards an indigenous design. The company was looking to increase the OH-1's range, and hoped to boost the Mitsubishi TS1-10 turboshaft engine's power output from 885shp (660kW) to 1,300shp. Other enhancements could include a new control system capable of gust alleviation, a new rotor hub, torque split transmission and an enhanced rotor blade erosion protection system.

The Ground Self-Defense Force had penciled in purchases of 180 to 200 OH-Xs. That would be far fewer than the 297 OH-6Ds KHI had through March 1995, and even this goal could fall prey to defense budget realities in Japan. A total of 20, including prototypes, had been ordered by FY02, with at least 12 delivered by late 2002. As of March 31, 2009, 28 have entered service so far, complementing the existing fleet of 111 OH-6s.

The Japan ground self-defence force will eventually require a replacement for its Fuji/Bell UH-1 utility helicopters. The OH-1 light military reconnaissance helicopter could be modified to fulfil the UH-1 role. And some UH-60Js have been in service quite a while, and new helicopters are required to prepare for gradual attrition of the legacy type.

Japan also had a requirement to replace its AH-1F Cobras - about 100 or so attack helicopters. An August 1999 government attack helicopter study reversed indications from the Japan Defence Agency (JDA) in September 1998, when it issued AH-X requests for proposals (RFPs) to foreign airframe and engine manufacturers earlier than expected. At that time, the RFP was taken as a sign that a type selection could take place as early as mid-1999 instead of the previously expected schedule of 2001/2. With the 1999 study, however, the JDA looked unlikely to select its AH-1S successor until about 2003. At that time the AH-1S helicopters were expected to be phased out beginning in 2006.

As of the year 2000, contractors eager to replace Japan's 84 Fuji/Bell AH-1S attack helicopters anticipated a fresh request for information to be issued by the end of the year. According to Boeing, which was proposing the AH-64D Apache Longbow, this could be followed by a contract in around 2002 for 40-80 helicopters, with deliveries to the Japan Ground Self-Defence Force QGSDF) beginning 27 months later.

By 2004 Japan had too many defence programs chasing too little cash, and JDA could not afford to fund more than 15 aircraft programs simultaneously. The JGSDF planned to take delivery of 55 Apaches from 2006, at the current acquisition rate it would take nearly three decades to replace its Fuji/Bell AH-1 Cobras. Given the more than 100 Kawasaki/Hughes OH-6s that also needed to be replaced, the OH-1 purchase looked to take even longer to complete.

A Japanese AH-X design would possibly be based on the OH-1 scout helicopter developed by Kawasaki Heavy Industries. The OH-1Kai, which has been under study since the late 1990s, would be an anti-tank helicopter based on the KHI OH-1 battlefield reconnaissance helicopter, with a modified airframe and engines. Development of this indigenous design, sometimes referred to as the AH-2, would require importing more powerful turboshaft engines than those used aboard the OH-1. The all-Japanese helicopter also would need a new rotor/gearbox assembly, sensor/targeting package, armor-plated forward and centre fuselage, upgraded engines and transmission and additional weapons carriage. Japan had sought pricing and technical information on the LHTEC T800 and MTU/-Turbomeca/Rolls-Royce MTR-390 turboshafts, which are viewed as potential powerplants for the AH-2.

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Page last modified: 04-08-2012 19:03:28 ZULU