TYPE: Armed observation helicopter.

PROGRAMME: Developed to replace OH-6Ds of JGSDF. Japan Defence Agency (IDA) awarded Y2.7 billion (US$22.5 million) in FY92 to cover basic design phase of helicopter then provisionally designated OH-X; RFPs issued by JDA's Technical Research & Development Institute (TRDI) 17 April 1992; Kawasaki selected as prime contractor (60% of programme) 18 September 1992. with Fuji and Mitsubishi (20% each) as partners; 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]).

Programme included six prototypes (four flying, two for ground test); first aircraft (32001) rolled out at Gifu on 15 March 1996 and made first flight 6 August 1996, followed by second prototype on 12 November; OH-1 designation assigned late 1996; first, two XOH-ls handed over to JDA on 26 May and 6 June 1997; third flown on 9 January 1997, at which time earlier aircraft had accumulated some 30 and 20 hours, respectively; handed over 24 June 1997; fourth 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.

Name 'Ninja' reportedly given in 2002, but not officially confirmed.

CURRENT VERSIONS:

OH-1; Basic initial production version; as described.

Growth versions: Under study with more powerful engines (possibly LHTEC T800 or R-R/Turbomeca/MTU MTR 390) and uprated gearbox. OH-1Kai is possible candidate for AH-X requirement with tentative designation AH-2, armour-plated forward and centre fuselage, upgraded engines and transmission and additional weapons carriage.

CUSTOMERS; Total of 20, including prototypes, ordered by FY02; at least 12 delivered by late 2002. Japan Ground Self-Defence hoice requirement for 150 to 200.

Hiko Jikkentai (Flight Test Squadron) formed at Akeno with first four production aircraft on 27 March 2001; other deliveries by late 2002 included small numbers to Kasumigaura Bunko, Utsunomiya Bunko and Kyoiku Shien Hikotai (at Akeno), all of which are departments of the Army's Koku Gako (Aviation School).

COSTS: Funding for development, prototypes and flight testing Y2.5 billion in FY92, Y10.2 billion in FY93, Y50.1 billion in bY94 and Y23.3 billion in FY95. Unit costs of first four production lots Y1.924 billion (FY97), Y2.018 billion (FY9S), Y2.229 billion (FY99) and Y2.075 billion (FY00).

DESIGN FEATURES: Kawasaki hingeless, bearingless and 20mm ballistic-tolerant four-blade elastomeric main rotor and transmission system; Fenestron-type tail rotor with eight unevenly angled 'scissor' blades (35 and 55°); stub-wings for stores carriage. Active vibration damping system.

FLYING CONTROLS: Integrated AFCS and stability control augmentation system (SCAS).

STRUCTURE: Rotor blades and hub manufactured from GFRP composites; centre-fuselage and engines by Mitsubishi, tail umt/canopy/stub-wings/cowling by Fuji, rest by Kawasaki. Some 37% of airframe (by weight) in GFRP/CFRP.

LANDING GEAR: Non-retractable tailwheel type. Provision for wheel/skis on main units.

POWER PLANT: Twin 662kW FADEC-equipped Mitsubishi TS1-10QT turboshafts (XTS1-10 originally in prototypes). Possibility of off-the-shelf alternative engines not ruled out. Transmission has 30-rninute run-dry capability. Stub-wings can each carry a 235 litre auxiliary fuel tank.

ACCOMMODATION: Crew of two on tandem armoured seats (pilot in front). Flat-plate cockpit transparencies, upward-opening on starboard side for crew access.

AVIONICS: Flight: AFCS with stability augmentation and holding functions; dual HOCAS controls.
Instrumentation: Two Yokogawa Electric large, fiat-panel, liquid crystal colour MFDs in each cockpit, linked to a MIL-STD-1553B databus; Shimadzu HUD in front cockpit.
Mission: Kawasaki electrically operated roof-mounted turret combining Fujitsu thermal imager, NEC real-time colour TV camera and NEC laser range-finder/designator: field of regard 110° in azimuth, 40° in elevation.
Self-defence: Spine-mounted IR jammer based on BAE Systems AN/ALQ-144.

ARMAMENT: Four Toshiba Type 91 (modified) lightweight short-range, IR-guided AAMs on pylons under stub-wings for sell-defence.

Jane's All the World's Aircraft, 2004-2005

Technical data for OH-1 Main rotor diameter: 11.6m, fuselage length: 12.0m, height to top of rotor head: 3.4m, height over tailfin: 3.8m, empty weight: 2450kg, normal take-off weight: 3550kg, max take-off weight: 4000kg, max level speed: 277km/h, combat radius: 200km, range: 550km