Shin Meiwa US-1A

The Shin Meiwa PS-1 and US-1A (新明和 PS-1, US-1A) are large STOL aircraft designed for anti-submarine warfare (ASW) and air-sea rescue (SAR) work respectively. The PS-1 was a flying boat which carried its own beaching gear on board, while the US-1A is a true amphibian.

Design and development
In 1960, Shin Meiwa demonstrated a prototype flying boat, the UF-XS, that featured a novel boundary layer control system to provide enhanced STOL performance. The company also built upon its wartime experience (as Kawanishi) to refine the Grumman Albatross hull that the aircraft was based on. In 1966, the JMSDF awarded the company a contract to further develop these ideas into an ASW patrol aircraft. Two prototypes were built under the designation PS-X and flight tests began on October 5, 1967, leading to an order for production under the designation PS-1 in 1969.

Apart from the boundary layer control system (powered by an independent gas turbine carried in the fuselage), the aircraft had a number of other innovative features, including a system to suppress spray during water handling, and directing the exhaust from the aircraft's four turboprop engines over its wings to create yet more lift. Between 1971 and 1978, the JMSDF ordered 21 of these aircraft, and operated them until 1989 when they were phased out and replaced with P-3 Orions. The small production run resulted in an extremely high unit-cost for these aircraft, and the programme was politically controversial.

The PS-1 ASW variant carried homing torpedoes, depth charges and 127mm rockets as offensive armament but had no defensive weapons. It was equipped with dipping sonar, which had limited use as it required the aircraft to land on water to deploy. It could also carry up to 20 sonobuoys. It had a crew of ten: pilot, co-pilot, flight engineer, navigator and six sensor/weapons operators.

The PS-1 had not been in service long before the JMSDF requested the development of a search-and-rescue variant. The deletion of the PS-1's military equipment allowed for greater fuel capacity, workable landing gear, and rescue equipment. The new variant, the US-1A, could also quickly be converted for troop-carrying duties. First flown on October 15, 1974, it was accepted into service the following year, and eventually 19 aircraft were purchased. From the seventh aircraft on, an uprated version of the original engine was used, but all aircraft were eventually modified to this US-1A standard. The US-1A's first rescue was from a Greek vessel in 1976. Between that time and 1999, US-1As had been used in over 500 rescues, saving 550 lives.

One PS-1 was experimentally modified for aerial firefighling in 1976 with an internal capacity of 7350 l of water.

With the US-1A fleet beginning to show its age, the JMSDF attempted to obtain funding for a replacement in the 1990s, but could not obtain enough to develop an entirely new aircraft. Therefore, in 1995, ShinMaywa began plans for an upgraded version of the US-1A, the US-1A kai (US-1A 改 - "improved US-1A"). This aircraft features numerous aerodynamic refinements, a pressurised hull, and more powerful Rolls-Royce AE 2100 engines. Flight tests began on December 18, 2003. The JMSDF purchased up to 14 of these aircraft, around 2007 and entered service as the ShinMaywa US-2.

Concept aircraft not built
In 1977 Shin Meiwa had several ideas for it's STOL flying boat concept on the drawing board but none were ever built. They were the Shin Meiwa LA (Light Amphibian), a 40 passenger light amphibian for inter-island feeder service; the 400 passenger Shin Meiwa MA (Medium Amphibian); the Shin Meiwa MS (Medium Seaplane) a 300 passenger long range flying boat with its own beaching gear; and the gargantuan Shin Meiwa GS (Giant Seaplane) that has a passenger capacity of an astonishing twelve-hundred (1200) passangers seated on three decks! Unlike the Shin Meiwa LA and MA which were like the US-1 in design the Shin Meiwa MS and GS had it engines located in front of and above the wing like the USAF Boeing YC-14 to give STOL effect. In the end, none of the four designs got beyond the drawing boards.

Operators

 * 🇯🇵 : Japan Maritime Self Defense Force