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The Sikorsky H-5, (aka R-5, S-51, HO2S-1, HO3S-1) (R-5 until 1948; company designation VS-327)〔Fitzsimons, Bernard, general editor. ''Illustrated Encyclopedia of 20th Century Weapons and Warfare'' (London: Phoebus, 1978), Volume 20, p.2173, "R-5, Sikorsky".〕 was a helicopter built by Sikorsky Aircraft Corporation, formerly used by the United States Air Force, and its predecessor, the United States Army Air Forces, as well as the United States Navy and United States Coast Guard (with the designations HO2S and HO3S). It was also used by the United States Post Office Department.〔("What Happens When You Mail a Letter." ) ''Popular Science,'' December 1951.〕 In December 1946, an agreement was signed between the British company Westland Aircraft and Sikorsky to produce a British version of the H-5 or S-51, to be manufactured under license in Britain as the Westland-Sikorsky WS-51 Dragonfly. By the time production ceased in 1951, more than 300 examples of all types of the S-51/H-5 had been built. ==Design and development== The H-5, originally designated the R-5 by the military, was designed to provide a helicopter having greater useful load, endurance, speed, and service ceiling than the Sikorsky R-4. The R-5 differed from the R-4 by having an increased rotor diameter and a new, longer fuselage for two persons in tandem.〔 Larger than the R-4 or the later R-6, the R-5 was fitted with a more powerful Wasp Junior 450-hp radial engine, and quickly proved itself the most successful of the three types.〔Rawlins 1976, p. 2.〕 The first XR-5 of four ordered made its initial flight on 18 August 1943. In March 1944, the United States Army Air Force ordered 26 YR-5As for service testing, and in February 1945, the first YR-5A was delivered. This order was followed by a production contract for 100, outfitted with racks for two litters (stretchers); only 34 were actually delivered.〔 Sikorsky soon developed a modified version of the YR-5A, the S-51, featuring a greater rotor diameter, greater carrying capacity and gross weight, which first flew on 16 February 1946.〔 With room for three passengers plus pilot, the S-51 was initially intended to appeal to civilian as well as military operators, and was the first helicopter to be sold to a commercial user.〔Rawlins 1976, pp. 2–3.〕 Eleven S-51s were ordered by the USAF and designated the R-5F, while ninety went to the Navy as the HO3S-1, commonly referred to as the 'Horse'.〔 In Britain, Westland Aircraft began production in 1946 of the Westland-Sikorsky S-51 Dragonfly for the Royal Navy and the Royal Air Force, all of which were powered by a 500 hp Alvis Leonides engine. This gave an improved top speed of 103 mph and a service ceiling of 14,000 ft. In total, 133 Westland-Sikorsky Dragonfly helicopters were built. A considerably modified version was also developed by Westland as the Westland Widgeon, but the type was never adopted for service. The U.S. Navy ordered four S-51s "off-the-shelf" from Sikorsky in late 1946 for use in the Antarctic and Operation Highjump, placing them into naval inventory as the HO3S-1.〔Rawlins 1976, p. 4.〕 Carried aboard the seaplane tender , on Christmas Day 1946 an HO3S-1 of VX-3 piloted by Lieutenant Commander Walter M. Sessums became the first helicopter to fly in the Antarctic. Having proved its capabilities, the initial naval HO3S-1 order was followed by subsequent purchases of an additional 42 aircraft in 1948.〔Rawlins 1976, pp. 2, 19.〕 The Navy equipped several warship classes with HO3S-1 utility helos, including aircraft carriers, seaplane tenders, icebreakers, s, and s. By February 1948, the Marine Corps had equipped HMX-1, its first regular Marine Helicopter Transport Squadron, with six HO3S-1 aircraft. With a passenger load of only three lightly dressed persons, the HO3S-1s were primarily operated in the utility role by the marines; for the transport role, an additional nine tandem-rotor Piasecki-built HRP-1 helicopters were later added to the squadron.〔Rawlins 1976, p. 20.〕 Eventually, the U.S. Navy would acquire a total of 88 HO3S-1 (S-51) helicopters. Twenty-one Sikorsky YR-5As were fitted with a third seat, rescue hoist, auxiliary external fuel tank, and nosewheel; the United States Navy evaluated three, as the HO2S-1.〔 Five more were converted as dual-control YR-5Es.〔 Thirty-nine additional specialized rescue helicopters were built, as the H-5G, in 1948, while 16 were fitted with pontoons as the H-5H amphibian in 1949.〔 Several H-5Hs were converted in 1949 to a unique medical-evacuation role, with casualty stretchers loaded sideways through blister-hatches on the side of the fuselage. The back stretcher station was located just forward of the tail boom and the main stretcher station was located behind the crew cabin. The forward stretcher station could accommodate two casualties, who were accessible to the medic in flight, while the back stretcher station handled only one, not accessible to the medic during the flight. Very little information is known about the operational use of this modification by the USAF, this being abandoned shortly after tests in 1950.〔("Litter Blisters." ) ''Popular Mechanics'', February 1950, p. 105.〕 The R-5 had been designated under the United States Army Air Force system, a series starting with R-1 and proceeding up to about R-16. In 1947 with the start of the United States Air Force, there was a new system, and many aircraft, but not all, were redesignated. The R-6 became the H-6. The United States Army broke off with its own designation system in the 1950s, resulting in new designations for its helicopter projects (such as the HO-6).〔Polmar and Kennedy 1981, p. 227.〕 In 1962 under the new tri-service system (see 1962 United States Tri-Service aircraft designation system), many navy and army aircraft were given the low numbers. Under the 1962 system, the low H numbers were given to new aircraft. For example, H-6 was given to the HO-6, which entered service as the ''Cayuse''. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Sikorsky H-5」の詳細全文を読む スポンサード リンク
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