The Shin Meiwa PS-1 / US-1 & Harbin SH-5 Flying Boats (original) (raw)
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v1.1.6 / 01 oct 11 / greg goebel / public domain
* While the large flying boat is generally a thing of the past, there are a few survivors. Among them are the Japanese Shin Meiwa "PS-1" and "US-1", and the Chinese Harbin "SH-4". These big, elegant, four-turboprop aircraft remain in service in limited numbers. This document provides a short history of the PS-1, US-1, and SH-5.
[1] UX-FS
[2] PS-1 ASW FLYING BOAT
[3] US-1 SAR FLYING BOAT / US-1A / US-1A KAI
[4] HARBIN SH-5
[5] COMMENTS, SOURCES, & REVISION HISTORY
[1] UX-FS
* The Japanese Kawanishi aircraft company had designed a number of flying boats into World War II, most significantly the superlative H8K, one of the best flying boats of the conflict. While Japan's defense industries were suppressed by the American occupation authorities after the country's defeat, they slowly began to re-emerge as the US turned to Japan as an East Asian ally in the Cold War against the Soviet Union. The Kawanishi company was resurrected in 1949 as "Shin Meiwa", in the relatively humble role of a service company that overhauled American, and later Japanese, military and civil aircraft.
However, the company had not forgotten its roots, and in 1959 Shin Meiwa rebuilt a Grumman UF-1 Albatross flying boat provided by the US Navy to experiment with new flying boat concepts. The modified Albatross, designated the "UX-FS", performed its initial flight on 25 December 1962. The UX-FS was fitted with four engines, two of them the Albatross's normal Wright R-1820 radials with 1,065 kW (1,425 HP) each, plus two additional Pratt & Whitney R-1340 radials with 450 kW (600 HP) each. The aircraft's hull was extensively modified, and the Albatross's conventional tail was replaced by a tee tail.
The UF-XS was also fitted with a General Electric (GE) T58 turboshaft engine providing 935 kW (1,250 SHP), mounted above and behind the cockpit. This engine simply blew air over the flaps and tail to provide a "boundary layer control (BLC)" system for improved short take-off & landing (STOL) performance. The UF-XS was flown in trials into 1964, and validated many concepts in improved flying boat design.
[2] PS-1 ASW FLYING BOAT
* In January 1966, the Japanese Defense Agency (JDA) awarded Shin Meiwa a contract for further development of the company's flying boat concepts. The contract specified development of two full-scale prototypes, with the project designation "PX-S" and company designation "SS-2". The PX-S was intended primarily for antisubmarine warfare (ASW). Dr. Shizuo Kikuhara was in charge of the design team.
The first PX-S prototype took to the air from Kobe harbor on 5 October 1967, with the second following on 14 June 1968. Evaluation by the Japan Maritime Self-Defense Force (JMSDF) began late in 1968. The results of the evaluation were positive, and two preproduction "PS-1" aircraft were ordered in March 1969, with initial delivery in late 1971.
The PS-1 was powered by four General Electric T64-IHI-10 turboprop engines providing 2,280 kW (3,060 SHP) each, built under license by Ishikawajima-Harima Heavy Industries (IHI), mounted on a high-set wing. Each engine drove a three-blade reversible-pitch Hamilton Standard propeller. As with the UF-XS test aircraft, a GE T58 turboshaft engine, also built by IHI, was mounted in the upper center of the fuselage to drive a BLC system for improved STOL performance. In addition, the T58 could be used as an auxiliary power unit (APU). STOL capability was further enhanced by leading-edge slats on the outboard sections of the wings and the tailplane, as well as overwing spoilers and large flaps. Take-off speed was about 90 KPH (55 MPH).
The PS-1 featured a tall tee tail like that of the UF-XS. A fixed stabilizing float was fitted to each wingtip, and the aircraft had built-in retractable tricycle beaching gear, though it could only actually land on water. The nose gear retracted into the hull, while the main gear pivoted up into the sides of the fuselage.
The aircraft was fitted with an interesting system in which water was pumped alongside the fuselage to suppress sea spray; spray was also deflected by strakes mounted alongside the nose of the aircraft. These measures helped to ensure that the engines wouldn't be flooded with sea water on landings and takeoffs. A sea anchor was carried in the bow. The aircraft's boat hull was unusually slender, making it very stable in rough seas, and it could land and take off in swell heights of up to 4.3 meters (14 feet). Most flying boats can operate only on calm seas or protected waters, but the PS-1 was capable of landings and takeoffs under severe ocean conditions. The seaworthiness of the PS-1 was far beyond that of any World War II flying boat.
Sensor systems included search radar with the antenna in a prominent nose radome; a "magnetic anomaly detection (MAD)" system with a retractable tail "stinger; a "Jezebel" passive sonar system with 20 sonobuoys; a "Julie" active sonar system using explosive charges to generate sound pulses for the sonobuoys; and a searchlight mounted under the right wing. Four 150 kilogram (330 pound) depth charges could be carried internally. Pods between the engines on each wing could carry two homing torpedoes each, for a total of four torpedoes, while a pod on each wingtip could accommodate three 127 millimeter (5 inch) rockets, for a total of six rockets. There was no defensive armament.
The PS-1 carried a crew of nine, including pilot and copilot; flight engineer; radio operator; radar operator; MAD operator; two sonar operators; and a tactical coordinator. The raised flight deck provided excellent visibility, and bunks were included for long-range patrols. The end result was a very appealing aircraft, a worthy successor to the H8K of World War II.
* The JMSDF ordered a total of 21 PS-1s, not counting the two prototypes, with the last delivered in the spring of 1978. However, as often happens with Japanese defense programs, the protracted development and small production run of the PS-1 led to very high unit costs. The program was politically controversial, all the more so because PS-1s suffered a series of accidents -- though the mishaps were not related to design or construction faults. Another difficulty was that though the idea of using a flying boat for ASW operations had its attractions, in that the aircraft could set down on the water and drop a dunking sonar to hunt for submarines, in practice land-based aircraft could do a perfectly adequate job of ASW at much lower cost. Procurement of the PS-1 was halted in 1980 in favor of the Lockheed P-3C Orion, and the PS-1 was completely out of service by 1989.
[3] US-1 SAR FLYING BOAT / US-1A / US-1A KAI
* Retirement of the PS-1 did not take Japan completely out of the flying boat business. Early in PS-1 production, the JMSDF asked Shin Meiwa to develop an amphibian version of the PS-1 for the "search and rescue (SAR)" role to replace the service's Grumman UF-1 Albatross flying boats. The new SAR flying boat was given the military designation of "US-1" and the company designation of "SS-2A". Since the aircraft was effectively just a PS-1 with different kit, there was no US-1 prototype. Initial flight of the first US-1 was on 15 October 1974, with introduction to service in 1975.
The US-1 looks much like the PS-1, but lacks armament and all sensor systems except ocean search radar. It has additional fuel capacity and is fitted with true landing gear to allow it to take off and land on airstrips. The main gear resembles that of the PS-1, but is scaled up, featuring two wheels on each gear assembly, and retracts into prominent fairings on the fuselage under the wings. The track is narrow, but the aircraft still handles well on crosswind landings.
Additional "bubble" windows are provided for observers, and along with rescue hatches with folding ramps, a large sliding door is built into the right side of the aircraft to allow launch and recovery of an inflatable rescue dinghy. A hoist is fitted above the sliding door; a loudspeaker system allows the flight crew to give instructions to survivors; and a dye-marker launcher with a capacity of ten markers can be used to mark patches of sea during rescue operations.
The US-1 has a crew of eight, including pilot; copilot; flight engineer; navigator; radio operator; radar operator; and two observers. Up to five medics or rescue divers can be carried as well. The aircraft can accommodate 12 stretchers and three sitting passengers, or 36 sitting passengers. In principle, the SAR gear could also be removed to allow conversion of the US-1 into a troop transport with seating for 100.
SHIN MEIWA US-1: _____________________ _________________ _______________________
spec metric english _____________________ _________________ _______________________
wingspan 33.15 meters 108 feet 9 inches wing area 135.82 sq_meters 1,462 sq_feet length 33.46 meters 109 feet 9 inches height 9.82 meters 32 feet 3 inches
empty weight 25,500 kilograms 56,220 pounds loaded weight 45,000 kilograms 99,200 pounds
max speed at altitude 495 KPH 310 MPH / 270 KT service ceiling 8,200 meters 27,000 feet range 4,200 kilometers 2,610 MI / 2,270 NMI _____________________ _________________ _______________________
An initial batch of 12 US-1s was built. The seventh and following aircraft were fitted with uprated T64-IHI-10J turboshaft engines providing 2,605 kW (3,490 SHP) each; these aircraft were designated "US-1A", and earlier production aircraft were upgraded to the same standard. A total of 20 US-1 / US-1A machines was manufactured up to the last example, built in 2004. The US-1 has proven extremely useful and capable, and was heavily employed in maritime SAR activities after the shoot-down of Korean Air Lines flight 007 by the Soviets in 1983. Up to 1999, the US-1 / US-1A was credited with saving 550 lives.
Shin Meiwa proposed a commercial transport version of the US-1 with seating for 69 passengers, but it was just too expensive and didn't happen. The first prototype of the PS-1 and a US-1 were also used in trials by the JMSDF and Japan National Fire Agency as a "water bomber" to fight forest fires.
* Despite the small production numbers of the PS-1 and US-1, production of the family is continuing with a new version, the "US-1A Kai", where "Kai" is short for "kaizen (modification)". The project was initiated in 1996, with the development contract specifying construction of two flight prototypes and two static-test prototypes. The first US-1A Kai prototype of performed its initial flight on 18 December 2003, taking off and landing in Osaka Bay.
The US-1A Kai is externally very similar to the US-1A, the most significant difference being that it is fitted with substantially more powerful Rolls-Royce AE-2100J engines, providing 3,425 kW (4,590 SHP) each, driving Dowty six-bladed propellers instead of the three-bladed propellers of the US-1A. The flap-blowing system is driven by an LHTEC CTS800-4K turboshaft, a civil version of the T800 military turboshaft, providing max power of about 1,015 kW (1,360 SHP). Performance and takeoff weight are improved.
The US-1A Kai also has a modified wing with integral fuel tanks and a pressurized upper cabin, permitting a ceiling of 6,100 meters (20,000 feet), twice that of the unpressurized US-1A. Avionics have been updated, including a glass cockpit and French Thales Ocean Master search radar. No doubt the modernized avionics suite includes a Global Positioning System navigation satellite receiver, a very handy item for an oceanic SAR machine, but such details are unclear. The first production machine went into formal JMSDF service in 2007. It is unclear IHI is license-building the AE-2100J engines.
It was initially believed that all seven surviving US-1As would be upgraded to US-1A Kai standard and that three production US-1A Kai machines would be built, but considering how previous purchases in the series have been strung out from year to year, an estimate of how many US-1A Kai machines will be built would probably not be very meaningful. The Japanese government considered buying a foreign machine, most likely a modern Russian Beriev flying boat, but decided -- probably for political reasons, though it is plausible that no other machine really fit JMSDF needs -- to buy from a domestic manufacturer, even though with such low production rates a foreign machine would be much cheaper. Whatever the case, in the 21st century the big Shin Meiwa machine remains a lovely testament to the romance of the flying boat.
[4] HARBIN SH-5
* While the Japanese were developing the PS-1, the Chinese began work on a comparable aircraft. In early 1970, after several years of consideration of various preliminary designs, the Harbin Aircraft Manufacturing Corporation (HAMC) and the Chinese Seaplane Design Institute began formal work on a four-turboprop flying boat that could be used for maritime warfare, SAR, and cargo transport roles. The aircraft was to be designated the "Maritime Bomber 5 (Shuishang Hongzhaji 5 / SH-5)", though sources mention an alternate "PS-5" designation.
A static test airframe was completed in 1971, but due to the upheavals and lunacy of the Chinese "Cultural Revolution", tests did not begin until August 1974. A flying prototype had been rolled out in December 1973, with the machine beginning taxi trials in May 1975 and performing its first flight on 3 April 1976. The slow pace of the program continued, a single production batch of six aircraft being completed in 1984 and 1985, with four of them handed over to the People's Liberation Army Naval Air Force in 1986. They have been retained in service, and may have received some combat electronic system updates.
* The SH-5 has a very general resemblance to the PS-1 / US-1, with a long, relatively slender, fuselage and hull, a high wing with four turboprops, and a fixed float near each wingtip. However, when inspected in more detail it clearly more resembles Soviet Beriev flying boat designs, with a twin-fin tail and very similar nose layout.
The SH-5 is powered by four Dongan WJ5A turboprop engines with 2,350 kW (3,150 SHP) each, driving four-bladed propellers. The aircraft is a pure seaplane, though it does have built-in beaching gear roughly similar to that of the PS-1. There are spray-suppression strakes on each side of the nose, and a small sea rudder at the rear of the hull.
The SH-5 is armed with a dorsal turret mounting twin cannon, and there are two stores pylons on each wing, one placed between the hull and the inboard engine, the second placed between the inboard and outboard engines. These four stores pylons can each be fitted with an antishipping missile, or each of the outer stores pylons can be fitted with three homing torpedoes. Six tonnes (13,200 pounds) of other stores, such as depth charges, mines, bombs, sonobuoys, or rescue gear can be stored in a rear compartment in the fuselage. A Doppler search radar is fitted in a thimble radome in the nose, and a fixed MAD boom is fitted to the tail. If configured as a cargolifter, the SH-5 can carry 10 tonnes (22,000 pounds) of cargo.
The SH-5 carries a flight crew of eight, including a pilot; co-pilot; navigator; flight engineer; radio operator; and three systems specialists. The number of specialists may vary depending on the mission. The fuselage is unpressurized. There are three freight compartments behind the cockpit area, followed by a cabin for the mission crew, a compartment for communications gear, and finally the stores compartment. There is a corridor connecting all three compartments, with watertight doors between compartments. There is one crew door on the left side of the aircraft and two doors on the right.
HARBIN (HAMC) SH-5 FLYING BOAT (ASW CONFIGURATION): _____________________ _________________ _______________________
spec metric english _____________________ _________________ _______________________
wingspan 36 meters 118 feet 1 inch wing area 144.0 sq_meters 1,550.05 sq_feet length 38.9 meters 127 feet 8 inches height 9.8 meters 32 feet 2 inches
empty weight 26,500 kilograms 58,400 pounds max loaded weight 45,000 kilograms 99,200 pounds
max speed at altitude 555 KPH 345 MPH / 300 KT service ceiling 10,250 meters 33,650 feet range 4,750 kilometers 2,950 MI / 2,565 NMI _____________________ _________________ _______________________
One of the aircraft not delivered to the Navy was apparently evaluated as a "water bomber" for fighting forest fires. It seemed that the SH-5 was a dead-end type for years, but in 2009 the Chinese Avic aviation manufacturing group announced plans for a new variant, the "Jiaolong", named after a type of Chinese sea dragon. Digital models show an aircraft that looks much like the SH-5, but lacks the nose glazing and MAD boom, and has a smaller nose radome. It is intended for fire-fighting and SAR, with introduction to service currently scheduled for 2014.
[5] COMMENTS, SOURCES, & REVISION HISTORY
* Sources include:
- THE ILLUSTRATED ENCYCLOPEDIA OF 20TH CENTURY WEAPONS AND WARFARE, edited by Bernard Fitzsimons, 1978 edition.
- MODERN WARPLANES by Doug Richardson, Crescent Books, 1982.
- JANE'S ALL THE WORLD AIRCRAFT, 1992:1993 edition.
- "Shin Meiwa PS-1 / US-1: Japan's Big Boat" by David Donald, WORLD AIR POWER JOURNAL, Volume 15 Winter 1993, 126:133.
- "Taking Off" by Eiichiro Sekigawa, AVIATION WEEK, 16 February 2004, 26.
- "Sea Dragon" by Bradley Ferrett, AVIATION WEEK, 28 September 2009, 34.
* Revision history:
v1.0 / 01 may 01 / gvg / Originally discussed PS-1 / US-1 only. v1.1.0 / 01 jan 02 / gvg / Added comments on Chinese SH-5. v1.1.1 / 01 apr 02 / gvg / Minor typo fixes. v1.1.2 / 01 apr 04 / gvg / Added US-1A Kai material, small fixes. v1.1.3 / 01 apr 06 / gvg / Review & polish. v1.1.4 / 01 feb 08 / gvg / Review & polish. v1.1.5 / 01 mar 09 / gvg / Jiaolong comments. v1.1.6 / 01 oct 11 / gvg / Review & polish.
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