R-6 / R-7 / HOS-1 Hoverfly II
Igor Sikorsky designed the R-6 as a follow on to his fabric covered HNS-1 (R-4). While retaining the R-4's rotor and transmission system, the R-6 had an all-metal fuselage. Twenty-seven experimental models were constructed and Nash Kelvinator, under license from Sikorsky, built all 193 production versions, designated as the R-6A.
The Sikorsky (model S-49) R-6 (British name Hoverfly MK II) was first flown on October 15, 1943. A refinement of the R-4, the R-6 (VS-316B) featured a larger, improved, streamlined metal fuselage with improved pilot visibility. This was a joint U.S. Army/U.S. Navy program. It had the same rotor and transmission as the R-4, but a more powerful 245 hp Franklin O-405-9 engine. It had a crew of two, seated side-by-side. It was equipped with a high-frequency radio. In the MedEvac role it could be equipped with two external capsules to carry litters. Bomb racks could be installed to carry 650 lbs. of bombs externally.
The R-6A could also be equipped with pontoons for use over water. The R-6A was the first USAAF helicopter to serve in combat in May 1944. The initial XR-6 and all five XR-6As were produced by Sikorsky. All R-6As were produced in 1944 and 1945 by Nash-Kelvinator under license to Sikorsky. The R-6A was used primarily by the U.S. Navy (as the HOS-1) and the U.S. Coast Guard, as well as the Royal Navy (as the Hoverfly MK II). Models A thru C were powered by a Pratt & Whitney R-985-AN-5 450 hp engine. The D model was powered by a Pratt & Whitney R-1340 600 hp engine.
Cancelled development of XR-6A.
The Navy procured three of the experimental models, designated XR-6A, from the Army Air Force's acquisitions in late-1943 and were given the Navy designation of XHOS-1. One was sent to Floyd Bennett Field for evaluation by the Coast Guard. The Navy then acquired 36 R-6As (which were then redesignated as HOS-1s) from the Army Air Force and the Coast Guard purchased 27 of these between January 1945 and January 1946. Of these, two were destroyed in crashes (no fatalities), and the rest were returned to the Navy by May 1949.
Some of the HOS-1s were assigned with the Coast Guard's Rotary Wing Development Unit, based out of Air Station Elizabeth City, North Carolina. Here they were used as test-bed platforms for new types of search and rescue equipment as well as equipment designed to improve the flight characteristics of the helicopters and their safety. Such equipment including a hover stabilizer, external fuel tanks, flotation gear, rescue hoists, and rescue baskets. They also made various modifications to the fuselage to permit the stowage of a stretcher, including a novel design whereby the stretcher was placed perpendicularly behind the pilot with either end sticking out of the fuselage. These exposed ends could be protected in flight by two cigar tube shaped objects that attached to the fuselage. The more successful design had the stretcher placed within the fuselage, facing fore and aft, next to the pilot. Some of the more famous Coast Guard aviators who participated in these developments included Frank Erickson, Stewart Graham, and August Kleisch.
This particular model of helicopter is best known in Coast Guard history as having been instrumental in the "Miracle at Gander" rescue. A Sabena Airlines DC-4 passenger aircraft crashed into a hillside 20 miles southeast of Gander, Newfoundland, on Wednesday, 18 September 1946, while attempting to land at the Gander airport. The aircraft had left Shannon, Ireland airport at 1700 the day before for a trans-Atlantic flight with 37 passengers and a crew of seven. A TWA pilot, Ray Jennings, while making a landing approach to the airport, reported the location of the wreck the next day after seeing what appeared to be a crash site. The location was so remote that it was thought the only way to get a rescue party there was by helicopter and the call went out for assistance. The Coast Guardsmen rescued 18 survivors of the airliner's passengers and crew. The pilots of the helicopters and PBYs were all awarded Air Medals as well as the Belgian "Knight of the Order of Leopold" medals. In this major rescue effort, the usefulness of the new helicopters in saving lives in remote locations became evident and secured a place in the Coast Guard's inventory for these rotary-winged aircraft.
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