Sikorsky R-4

infobox Aircraft
name = R-4 / Hoverfly
type = Helicopter
manufacturer = Sikorsky

---

caption = Comdr. Frank A. Erickson, USCG & Dr. Igor Sikorsky, Sikorsky Helicopter HNS-1 C.G. #39040.
designer = Igor Sikorsky
first flight = 13 January 1942
introduced =
retired =
status =
primary user = United States Air Force
more users = United States Navy United States Coast Guard Royal Air Force
produced = 1942-1944
number built = 131
unit cost =
developed from = Vought-Sikorsky VS-300
variants with their own articles = Sikorsky H-5

The Sikorsky R-4 was "the world's first mass produced helicopter and the United States Air Force's first service helicopter" [http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=518 National Museum information] ]

Development

The VS-316, was developed from the famous experimental VS-300 helicopter, invented by Igor Sikorsky and publicly demonstrated in 1940. The VS-316 was designated the XR-4, under the United States Army Air Forces' series for "Rotorcraft". The XR-4 made its initial flight on 13 January, 1942 and as a result of its successful flight tests, the United States Army Air Forces ordered three YR-4As and 27 YR-4BsFact|date=April 2007 for service testing and flight training.

Operational history

The R-4 was first used in combat in May 1944. In a letter to a friend, Col. Philip G. Cochran, commanding officer of the 1st Air Commando Group, wrote "Today the 'egg-beater' went into action and the damn thing acted like it had good sense." The R-4 showed such promise that the AAF ordered 100 R-4Bs.

Of these 30, one went to Burma and one to Alaska, while several others were assigned to the United States Navy, United States Coast Guard and Royal Navy who named it the Gadfly. In Royal Air Force service it was called the Hoverfly. The R4 equipped the first British military unit to be equipped with helicopters, the Helicopter Training School, formed in January 1945 at RAF Andover.

Variants

External differences noted in photos: Some R-4s had the tail wheel located at the extreme aft end of the boom near the tail rotor while others had it positioned at the mid-point of the boom. Additionally, some had short "stub" exhaust pipes from the engine while others had a much longer one which extended vertically and then aft above the main landing gear struts.

;XR-4:One prototype Model VS-316A with a crew of two and dual controls, 165hp R-500-3 engine, became XR-4C;YR-4A:Version with larger rotor diameter and a 180hp R-550-1 engine; three built.;YR-4B:Version with detailed changes. 27 built for development testing followed by a further batch of 14, seven to US Navy as HNS-1s. ;R-4B:Production version with 200hp R-550-3 engine. 100 built including 20 for the US Navy and 45 for the Royal Air Force.;XR-4C:Prototype XR-4 re-engined with 180hp R-550-1 engine with the larger YR-4A type rotor.;HNS-1:Three YR-4Bs and 22 R-4Bs transferred to the US Navy, two diverted to the United States Coast Guard.;Hoverfly I:UK military designation of the R-4 for the Royal Air Force and Royal Navy, 52 delivered and one later transferred to the Royal Canadian Air Force.;XR-6:Redesigned R-4B with 235-hp Franklin O-405-9 engine; one built.;R-6A:Production version of the XR-6. Six built by Sikorsky and 219 built under license by Nash-Kelvinator. [http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=523]

Operators

;CAN:Royal Canadian Air Force;UK
*Royal Air Force
*Fleet Air Arm;flag|United States|1912
*United States Army Air Force
*United States Navy
*United States Coast Guard

Aircraft on display

* Smithsonian Museum's Steven F. Udvar-Hazy Center has the XR-4C prototype
* National Museum of the United States Air Force at Wright-Patterson AFB near Dayton, Ohio
* RAF Museum at Hendon in north London
* Canada Aviation Museum in Ottawa, Ontario
* National Museum of Naval Aviation in Pensacola, Florida. Exhibit is an HNS-1 Hoverfly (Bureau Number 39047) - On indoor static display in US Coast Guard markings.
* Army Aviation Museum at Fort Rucker, Alabama. U.S. Army R-4B Hoverfly (Serial Number 43-46592) and R-6A Hoverfly II (Serial Number 43-45473) on indoor static display. [U.S. Army Aviation Museum Association, Inc. [http://www.armyavnmuseum.org/museum/collection/rw3.html "Rotary Wing Collection"] . www.armyaviationmuseum.com. 2 January 2003. Accessed on 25 August 2008.]

pecifications (R-4B)

aircraft specifications
plane or copter?=copter
jet or prop?=prop

crew=1
capacity=
length main= 33 ft 8 in
length alt= 10.2 m
span main= 38 ft
span alt= 11.5 m
height main= 12 ft 5 in
height alt= 3.8 m
area main=
airfoil=
empty weight main=2,098 lb
empty weight alt=952 kg
loaded weight main= 2,581 lb
loaded weight alt= 1,170 kg
useful load main=
more general=
engine (prop)=Warner R-550
type of prop=piston
number of props=1
power main= 200 hp
power alt= 149 kW
power original=
max speed main= 75 mph
max speed alt= 120 km/h
cruise speed main= 65 mph
cruise speed alt= 105 km/h
never exceed speed main=
ceiling main= 8,000 ft
ceiling alt= 2400 m
climb rate main=
thrust/weight=
power/mass main=
more performance=
armament=
avionics=

ee also

aircontent
related=
* Vought-Sikorsky VS-300
* Sikorsky R-5
similar aircraft=

References

Notes

Bibliography

* Myall, Eric and Sturtivant, Ray (ed.). "The Hoverfly File". Tunbridge Wells, Kent, UK: Air-Britain (Historians) Ltd., 1998. ISBN 0-85130-262-9.

External links

* [http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=518 Sikorsky R-4 page at the National Museum of the United States Air Force]
* [http://www.rafmuseum.org.uk/sikorsky-r-4b-hoverfly-1.htm RAF Museum Sikorsky R4 Hoverfly webpage]
* [http://www.plastikowe.pl/galerie/lotnictwo/sikorsky-r-4b-hoverfly-i Photo gallery of Sikorsky R-4B Hoverfly I]