Sikorsky R-4B Hoverfly
Wartime colour photograph of US Hoverfly


The Sikorsky R-4 Hoverfly (RAF/FAA designation of YR-4B & R-4B) was the first practical helicopter and the most important forerunner of all civil and military rotary wing aircraft now flying around the world. The original military model, the XR-4, was developed from the famous experimental VS-300 helicopter, invented by Igor Sikorsky and publicly demonstrated in 1940.

In the spring of 1941 a prototype helicopter designed by Igor Sikorsky was performing well enough to warrant a contract being awarded to the Vought-Sikorsky division of United Aircraft for the development of a two-seat version, designated the XR-4. XR-4 had a covered fuselage, side-by-side seating and dual controls. The flying controls in the XR4 set the standard for all subsequent helicopters. The XR4 was re-engined in 1943 and called XR4C. Service trials with the YR-4A and YR-4B, including one from a tanker, resulted in the final variant, the R-4B.

The first flight of the new helicopter was made in January 1942, and 130 production
examples were produced. The R-4 recorded two firsts: it accomplished the first
helicopter landing aboard a ship, and the first rescue by a helicopter. Twenty-five R-4s
(under the designation HNS-1) were operated by the US Navy and US Coast Guard, and
52 R-4s were operated by the RAF and FAA.

Fleet Air Arm history
    Hoverfly I (RAF/FAA designation of YR-4B & R-4B)
    Total FAA 1939-1945:        24
    First delivered to RN:         1944
    First squadron 1939-1945:   1944
    Operational squadron:          None
    Last served with RN            Postwar till 1948
The Hoverfly I (RAF/FAA designation of YR-4B & R-4B) was the Fleet Air Arm's first helicopter. 24 were bought. The first, FT837 (ex 43-28232), was accepted March 1944
Hoverfly (ex 42-1027246) Ex RAF, crashed 8 May 1944 but the rest of the firstr batch were delivered to RNFS Floyd Bennett Field, USA in June 1944 and coded A-D. All then delivered to the RN at Norfolk, Virginia in December 1944. They were then transported to the UK on aircarft carrier HMS Thane on 30 December 1944 probably to RDU Abbotsinch in mid January 1945.

The Hoverfly were delivered to 771 squadron at Twatt. Whilst with 771, FT836 reported fitted with pontoons for trials with HMS Furious in Scapa Flow. With 771 on July 1945 to Worthy Down. Another aircraft, FT839 was delivered to the Admiralty Signals Establishment Flight at Witley Park in March 1945. Some of the second batch were delivered to HMS Excellent Flight in January 1945.

The last of these aircraft, KK969, was still with 771 squadron in Portland in August 1948.

5 Sikorsky YR-4B Hoverfly I numbered T835-FT839.

First to RN:     accepted 3.44 FT837 (ex 43-28232) and FT838 (ex 43-28223). (ex 42-1027246)

First Sqdn       771 sqdn Twatt.

45 Sikorsky R-4B Hoverfly I
Serial numbered KK969 KL113. Mixed RAF and RN deliveries, the following to RN

Total RN:       19

First Accepted  Bridgeport 6-11.44, first RNFS Floyd Bennett Field 6.44, Norfolk, Va 12.44, Thane
                     29.12.44, RDU Abbottsinch c16.1.45, To 771 sqdn Twatt c late 1945

                     Others to Worthy Down 27.1.45, Admiralty Signals Flight , by early 1945, to HMS
                     Excellent Flt by 2.2.45, or to 7AAU Hooten Park 1.45 to HMS Excellent Fight

Last:              Still with 771 Portland 8.48 KK969.

Aircraft Type:
Sikorsky R-4 Hoverfly (HNS-1)
Primary Role:
Two-seat training and rescue helicopter/General Pupose helicopter
First Flight: 
January 1942
Date operating with FAA squadrons:
Sikorsky Aircraft Division of United Aircraft Corporation
One 200 hp Warner R-550 7-cylinder, fan-cooled, radial engine
 Wing Span: Length: Height: Wing Area: 
Rotor diameter: 38ft. 
Length  35 ft 5 in (10.8 m) 
Height 12 ft 5 in (3.78 m)
Empty Weight: Max.Weight:
Empty Weight 913 kg
Maximum Take Off Weight 1153 kg



Speed: 131km/h Ceiling: 2440m Range: 370km
Battle honours:
none with FAA
Additional references and notes:

Battle Honours and Operational History

None with the FAA, however the US version the R-4 was first used in combat in May 1944. A few saw service during WWII, flying casevac missions in Burma. In a letter to a friend, Col. Philip G. Cochran, CO of the 1st Air Commando Group, wrote: "Today the 'egg-beater' went into action and the damn thing acted like it had good sense.".

Surviving aircraft and relics
At least three Hoverfly I exist in the world, one at the RAF Museum another at the National Naval Aviation Museum (USA) and the third with the CAF Ghost Squadron (USA). The RAF Museum example, Sikorsky VS-316 Hoverfly I  KL110 is a former Fleet Air Arm aircraft.

Fleet Air Arm Hoverfly MkI KL110 at the RAF Museum
The R-4B on display at the AFMF Museum was donated by the University of Illinois in 1967.

Associations and reunions
No information
HOVERFLY FILE by Eric Myall The HOVERFLY FILE by Eric Myall   (Edited by Ray Sturtivant) 
 ISBN 0 85130 262 9
Museum specifications and history of the Hoverfly  Museum specifications and history of the Hoverfly donated by the University of Illinois 
Sturtivant, R. & Burrow, M (1995) Sturtivant, R. & Burrow, M (1995)  'Fleet Air Arm Aircraft 1939
to 1945'  Published by Air Britain (Historians) Ltd, 1995 ISBN: 0
85130 232 7 
CAF Ghost squadron aircraft  CAF Ghost Squadron's Hoverfly and history of the type
Created 3-4-1999, Modified 3-4-2000


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