| R-6 / Hoverfly II | |
|---|---|
 | |
| R-6A Hoverfly II in flight | |
| Role | Helicopter |
| National origin | United States |
| Manufacturer | Sikorsky Aircraft |
| First flight | 15 October 1943 |
| Introduction | 1945 |
| Status | Retired |
| Primary users | United States Navy Royal Air Force |
| Number built | 225 |
| Developed from | Sikorsky R-4 |
The Sikorsky R-6 is an American light two-seat helicopter of the 1940s. In Royal Air Force and Royal Navy service, it was named the Hoverfly II.
The R-6/Hoverfly II was developed to improve on the successful Sikorsky R-4. In order to enhance performance, a completely new streamlined fuselage was designed and the boom carrying the tail rotor was lengthened and straightened. The main rotor and transmission system of the R-4 were retained. [1] Sikorsky allotted their Model 49 designation to the new design. Later, dynamically balanced modifications to the rotor were carried out by Doman Helicopters Inc. The new aircraft could attain 100 mph (160 km/h) compared with 82 mph (132 km/h) by the earlier design.
Initial production was by Sikorsky, but most examples were built by Nash-Kelvinator. Some of the later aircraft were fitted with more powerful engines.
The first R-6s were delivered to the United States Army Air Forces (USAAF) in late 1944 and some were transferred to the United States Navy (USN). It was initially intended to pass 150 R-6s to the Royal Air Force (RAF), but delays caused by the switch of production from Sikorsky's factory at Stratford, Connecticut, to Nash-Kelvinator at Detroit, Michigan, meant that only 27 R-6As were actually delivered to the RAF as the Hoverfly II. [2] Fifteen of these were passed on to the Royal Navy's Fleet Air Arm (FAA). [3]
Some of the RAF examples were allotted to 657 Squadron RAF for proving the use of helicopters in the Army Co-operation role, and two external stretchers could be fitted to the fuselage. 657 Squadron operated their Hoverfly IIs as Air Observation Posts, spotting for Army artillery units. The Hoverfly IIs remained in operation until April 1951, and one squadron example was displayed at the September 1950 Farnborough Air Show. [4]
The FAA used their Hoverfly IIs in the training and liaison roles. Naval units to use the type included 771 Squadron from December 1945, followed by 705 Squadron.
The USAAF operated their R-6s in secondary roles and the survivors were redesignated H-6A in 1948. The USN examples were designated the HOS-1 and a further 64 were intended to be transferred from the USAAF, but this did not take place.
Disposals of surplus military S-49s were made in the civil market in the late 1940s but none now remain in operation. Four are currently displayed in US museums. [5]
United Kingdom 
United States 
Mexico 
Data from Thetford, 1977
General characteristics
Performance
Related development
The Westland Whirlwind helicopter was a British licence-built version of the U.S. Sikorsky S-55/H-19 Chickasaw. It primarily served with the Royal Navy's Fleet Air Arm in anti-submarine and search and rescue roles. It was also exported to other countries, and the Whirlwind was succeeded by the turbine powered Westland Wessex which was developed from the H-19/Whirlwind. The helicopter was made in many variants using a variety of radial (piston) and turbine engines.
The Westland Wessex is a British-built turbine-powered development of the Sikorsky H-34. It was developed and produced under licence by Westland Aircraft. One of the main changes from Sikorsky's H-34 was the replacement of the piston-engine powerplant with a turboshaft engine. Early models were powered by a single Napier Gazelle engine, while later builds used a pair of de Havilland Gnome engines.
The Sikorsky CH-37 Mojave is an American large heavy-lift military helicopter of the 1950s. It entered service as the HR2S-1 Deuce with USMC in 1956, and as the H-37A Mojave with the U.S. Army that same year. In the early 1960s, the designation was standardized to CH-37 for both services, with the HR2S-1 redesignated as CH-37C specifically.
The Sikorsky H-19 Chickasaw is a multi-purpose piston-engined helicopter that was used by the United States Army and United States Air Force. It was also license-built by Westland Aircraft as the Westland Whirlwind in the United Kingdom. United States Navy and United States Coast Guard models were designated HO4S, while those of the U.S. Marine Corps were designated HRS. In 1962, the U.S. Navy, U.S. Coast Guard and U.S. Marine Corps versions were all redesignated as H-19s like their U.S. Army and U.S. Air Force counterparts.
The Sikorsky H-34 is an American piston-engined military utility helicopter originally designed by Sikorsky as an anti-submarine warfare (ASW) aircraft for the United States Navy. A development of the smaller Sikorsky H-19 Chickasaw (S-55), the H-34 was originally powered by a radial engine, but was later adapted to turbine power by the British licensee as the Westland Wessex and by Sikorsky as the S-58T. The H-34 was also produced under license in France by Sud Aviation.
RAF Andover is a former Royal Flying Corps and Royal Air Force station in England, 2 miles (3.2 km) west of Andover, Hampshire. As well as RFC and RAF units, units of the Aviation Section, U.S. Signal Corps, Royal Canadian Air Force, United States Army Air Forces, and the Air Transport Auxiliary were also stationed at the airfield.
The Sikorsky R-4 is a two-seat helicopter that was designed by Igor Sikorsky with a single, three-bladed main rotor and powered by a radial engine. The R-4 was the world's first large-scale mass-produced helicopter and the first helicopter used by the United States Army Air Forces, the United States Navy, the United States Coast Guard and the United Kingdom's Royal Air Force and Royal Navy. In U.S. Navy and U.S. Coast Guard service, the helicopter was known as the Sikorsky HNS-1. In British service it was known as the Hoverfly.
The Sikorsky H-5 is a helicopter built by Sikorsky Aircraft Corporation.
The Cierva C.30 is an autogyro designed by Juan de la Cierva and built under licence from the Cierva Autogiro Company by A V Roe & Co Ltd (Avro), Lioré-et-Olivier and Focke-Wulf.
The Westland WS-51 Dragonfly helicopter was built by Westland Aircraft and was an Anglicised licence-built version of the American Sikorsky S-51.
The Bell R-12 was an American 1940s military utility helicopter built by the Bell Helicopter company. The design did not go into full production, but over a dozen prototypes were used for various tests and projects.
The Platt-LePage XR-1, also known by the company designation PL-3, is an early American transverse rotors helicopter, built by the Platt-LePage Aircraft Company of Eddystone, Pennsylvania. The winner of a United States Army Air Corps design competition held in early 1940, the XR-1 was the first helicopter tested by the USAAF, flying in 1941. The flight testing of the XR-1 proved troublesome, and although continued testing showed that the design had promise, other, improved helicopters were becoming available before the XR-1 was ready for service. As a result, the development of the aircraft was terminated in 1945.
The Doman LZ-5 was a utility helicopter developed in the United States in the early 1950s by Doman Helicopters Inc. of Danbury, Connecticut. Despite the procurement of international manufacturing agreements, no series production of the aircraft ever occurred, and only three prototypes were built. Two of these were purchased by the United States Army as the YH-31, but eventually becoming VH-31.
The Kellett XR-8 was a helicopter built in the United States during World War II. It was a two-seat machine intended to demonstrate the feasibility of a twin-rotor system and, while it accomplished this, it also demonstrated a number of problems that prevented further development of this particular design.
705 Naval Air Squadron was first formed as a flight in 1936 from No 447 Flight Royal Air Force and operated Swordfish torpedo bombers from battlecruisers. It achieved squadron status in 1939 before being disbanded in 1940. The squadron was re-formed briefly in 1945 and then again in 1947 as a fleet requirements unit to evaluate naval use of helicopters. Since the 1950s the squadron has been involved in the basic training of helicopter aircrew, and currently forms part of No. 1 Flying Training School at RAF Shawbury.
The Doman LZ-2A Pelican was an American five-seat helicopter designed and developed by Doman Helicopters of Danbury, Connecticut.
The Franklin O-405 was an American air-cooled aircraft engine of the 1940s. The engine was of six-cylinder, horizontally-opposed layout and displaced 405 cu in (6.64 L). The power output was between 200 hp (149 kW) and 250 hp (186 kW) depending on variant. The O-405-9 (6ACV-403) was a vertically mounted, fan cooled version for helicopters.
Glidden Doman was an American aeronautical engineer and pioneer in helicopters and modern wind turbines. He founded one of America's original six helicopter companies after making major contributions to the use of Sikorsky helicopters during World War II. Doman Helicopters' most prominent achievement was the Doman LZ-5/YH-31 eight-place helicopter, which received FAA certification on December 30, 1955. The unique feature of this helicopter was its hinge-less but gimbaled, tilting rotor hub that greatly reduced stress and vibration in the blades and the whole helicopter.
