TYPE: Four-turboprop amphibian.
PROGRAMME: First flown 16 October 1974; first delivery (as US-1) 5 March 1975; all now have T64-IHI-10J engines as US-1As.
CURRENT VERSIONS: US-1A: SAR amphibian, developed from PS-1 ASW flying-boat; manufacturer's designation SS-2A.
Data apply to US-1A except where indicated.
US-1AKai: Upgrade initiated in 1996: Rolls-Royce AE 2100J turboprops, six-blade Dowty propellers, modified wing with composites and integral fuel tanks, pressurised upper hull, Kawasaki FBW controls, 'glass cockpit', Thales Ocean Master radar, Honeywell RE-220 APU and LHTEC CTS800-based BLC compressor. Performance enhancements include maximum speed of 300 kt (555 km/h; 345 mph) , service ceiling of 6,100 m (20,000 ft), and a 50 per cent reduction in take-off distance on water.
Parts manufacture for first aircraft began in April 2000; static and fatigue test airframes completed; former began testing in 2001, latter due to start in October 2003. Construction of second flying prototype under way by third quarter 2002, at which time first prototype said to be on schedule for maiden flight in August 2003; latter (9901) rolled out 23 April 2003; first flight achieved on 18 December 2003. Second aircraft then expected to make maiden flight in March 2004. Service entry planned for mid-2006, replacing US-1As, which will be retired.
Firefighting amphibian: PS-1 modified in 1976 to firefighting configuration; 7,348 kg (16,200 lb) capacity water tank in centre-fuselage forward of step. One US-1A modified experimentally in 1986 to 1988, with more than 13,608 kg (30,000 lb) tank capacity.
CUSTOMERS: Total of 19 US-1/1As ordered, 18 of which delivered by end of 2000; none requested for FY00, but US$283 million requested instead to resume development of US-1AKai. One US-1A requested for FY02. Orders since 1988 have been for attrition replacements and, more recently, due to phase-out of older aircraft. No. 71 SAR Squadron of the JMSDF maintains fleet structure of seven aircraft at Iwakuni and Atsugi bases.
JMSDF said to have requirement for 14 US-1AKai to replace existing US-1A fleet; JDA expected to request initial batch of seven subject to successful completion of flight test programme.
DESIGN FEATURES: Large turboprop-powered amphibian, suitable for maritime patrol and sea rescue missions. Boundary layer control system and extensive flaps for propeller slipstream deflection for very low landing and take-off speeds; low-speed control and stability enhanced by blowing rudder, flaps and elevators, and by use of automatic flight control system (see Flying Controls). Fuselage high length/beam ratio; V-shaped single-step planing bottom, with curved spray suppression strakes along sides of nose and spray suppressor slots in lower fuselage sides aft of inboard propeller line; double-deck interior. Large dorsal fin.
FLYING CONTROLS: Digital flight control system controlling elevators, rudder and outboard flaps. Hydraulically powered ailerons, elevators (with tabs) and rudder, all with feel trim. High-lift devices include outboard leading-edge slats over 17 per cent of wing span and large outer and inner blown trailing-edge flaps deflection 60° and 80° respectively; outboard flaps can be linked with ailerons; inboard flaps, elevators and rudder blown by BLC system. Two spoilers in front of outer flaps on each wing. Inverted slats on tailplane leading-edge.
STRUCTURE: All-metal; two-spar wing box.
LANDING GEAR: Flying-boat hull, plus hydraulically retractable Sumitomo tricycle landing gear with twin wheels on all units. Steerable nose unit. Oleo-pneumatic shock-absorbers. Main units, which retract rearward into fairings on hull sides, have 40x14-22 tyres, pressure 7.79 bar (113 lb/sq in). Nosewheel tyres size 25x6.75-18, pressure 20.69 bar (300 lb/sq in). Three-rotor hydraulic disc brakes. No anti-skid units. Minimum ground turning radius 18.80 m (61 ft 8¼ in) towed, 21.20 m (69 ft 6¾ in) self-powered.
POWER PLANT: US-1A: Four 2,535 kW (3,400 shp) Ishikawajima-built General Electric T64-IHI-10J turboprops, each driving a Sumitomo-built Hamilton Sundstrand 63E60-27 three-blade constant-speed reversible-pitch propeller.
US-1AKai: Four 3,356 kW; (4,500 shp) Rolls-Royce AE 2100J turboprops, with FADEC and six-blade Dowty R414 propellers.
Fuel in five wing tanks, with total usable capacity of 11,640 litres (3,075 US gallons; 2,560.5 Imp gallons) and two fuselage tanks (10,849 litres; 2,866 US gallons; 2,386.5 Imp gallons); total usable capacity 22,489 litres (5,941 US gallons; 4,947 Imp gallons). Pressure refuelling point on port side, near bow hatch. Oil capacity 152 litres (40.2 US gallons; 33.4 Imp gallons). Aircraft can be refuelled on open sea, either from surface vessel or from another US-1A with detachable at-sea refuelling equipment.
ACCOMMODATION: Crew of three on flight deck (pilot, co-pilot and flight engineer), plus navigator, radio/radar operator and medical attendant's seats in main cabin. Latter can accommodate up to 20 seated survivors or 12 stretchers, one auxiliary seat and two observers' seats. Sliding rescue door on port side of fuselage, aft of wing.
SYSTEMS: Cabin air conditioning system. Two independent hydraulic systems, each 207 bar (3,000 lb/sq in). No. 1 system actuates ailerons, outboard flaps, spoilers, elevators, rudder and control surface feel; No. 2 system actuates ailerons, inboard and outboard flaps, wing leading-edge slats, elevators, rudder, landing gear extension/retraction and lock/unlock, nosewheel steering, mainwheel brakes and windscreen wipers. Emergency system, also of 207 bar (3,000 lb/sq in), driven by 24 V DC motor, for actuation of inboard flaps, landing gear extension/retraction and lock/unlock, and mainwheel brakes.
Honeywell 85-131J APU (RE-220 in US-1AKai) provides power for starting main engines and shaft power for 40 kVA emergency AC generator. BLC system includes a C-2 compressor, driven by a 1,119 kW (1,500 shp) Ishikawajima-built General Electric T58-IHI-10-M2 gas turbine, housed in upper centre portion of fuselage, which delivers compressed air at 14 kg (30.9 lb)/s and pressure of 1.86 bar (27 lb/sq in) for ducting to inner and outer flaps, rudder and elevators (US-1AKai has variant of LHTEC CTS800).
Electrical system includes 115/200 V three-phase 400 Hz constant-frequency AC and three transformer-rectifiers to provide 28 V DC. Two 40 kVA AC generators, driven by Nos. 2 and 3 main engines. Emergency 40 kVA AC generator driven by APU. DC emergency power from two 24 V 34 Ah Ni/Cd batteries.
De-icing of wing and tailplane leading-edges. Oxygen system for all crew and stretcher stations. Fire detection and extinguishing systems standard.
AVIONICS: Comms: HRC-121 HF, HRC-113 VHF and HRC-115-1 U/VHF radios; HIC-3B interphone; AN/APX-68-NB IFF transponder; RRC-22 emergency transmitter.
Radar: Thales OM-100 Ocean Master search radar.
Flight: HRN-101 ADF; OA-8697A/ARD UHF/DF; AN/ARN-118(V)2 Tacan; HRN-115-5 GPS nav system; HRN-107B-1 VOR/ILS receiver; AN/APN-171 (N2) radio altimeter; HPN-101B wave height meter; HSN-4 INS; N-TR-45 TAS transmitter; HRA-6-3 nav display; and N-ID-66/HRN BDHI.
EQUIPMENT: Marker launcher, 10 marine markers, six green markers, two droppable message cylinders, 10 float lights, pyrotechnic pistol, parachute flares, two flare storage boxes, binoculars, two rescue equipment kits, two droppable liferaft containers, rescue equipment launcher, lifeline pistol, lifeline, three lifebuoys, loudspeaker, hoist unit, rescue platform, lifeboat with outboard motor, camera, and 12 stretchers. Sea anchor in nose compartment. Stretchers can be replaced by troop seats.