Today in WW II: 4 Jul 1942 German bombers and submarines sink 24 ships of Convoy PQ 17 to the Soviet Union after the convoy spread out in the Arctic Ocean to evade the German battleship Tirpitz.  More ↓
4 Jul 1942 US Eighth Air Force flies its first mission in Europe using six borrowed British planes; only three aircraft returned.
Visit the Olive-Drab.com World War II Timeline for day-by-day events 1939-1945! See also WW2 Books.

R-4 Sikorsky Helicopter

The Sikorsky R-4 was the world's first production helicopter and the U.S. Army Air Corp's first service helicopter. 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.

The Army R-4 was Sikorsky Model S-47, with a fabric covered tubular steel fuselage. Model variants ranged from A through C. The YR-4B was a two-place side-by-side, observation, reconnaissance, and MedEvac helicopter, with one external litter rack. Other R-4s were fitted with twin pontoons for use aboard ships or over water.

The XR-4 made its initial flight on 13 January 1942, and as a result of its successful flight tests, the USAAF ordered three YR-4As and 27 YR-4Bs for service testing and flight training. Of these 30, one went to Burma and one to Alaska, while several others were assigned to the U.S. Navy, U.S. Coast Guard and British Royal Navy. They showed such promise that the USAAF ordered 100 R-4Bs. It was also procured by the British under the name Hoverfly MK I and by the U.S. Navy as the HNS-1. It was tested extensively by the Coast Guard who later procured follow-on Sikorsky models.

In Burma, the first helicopter MedEvac rescue took place in April 1944 and 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." In U.S. Navy testing, the R-4 became the first helicopter to land on a ship.

The R-4B was replaced by the versatile Sikorsky Model S-51, Army nomenclature R-5D, shortly after World War II.

R-4 Sikorsky Specifications and Performance

Rotor diameter 38 ft.
Length 33 ft. 7 3/4 in.
Height 12 ft. 5 in.
Weight 2,581 lbs. loaded
Armament None
Engine 200 hp Warner R-550
Maximum speed 75 mph
Cruising speed 65 mph
Range 130 miles
Service ceiling 8,000 ft.

Igor Sikorsky and Orville Wright by Sikorsky XR-4 helicopter at Wright Field, OH, May, 1942.
Igor Sikorsky and Orville Wright standing by a Sikorsky XR-4 helicopter at Wright Field, OH, May, 1942.

Sikorsky R-4B at the National Museum of the U.S. Air Force. Donated to the museum by the University of Illinois in 1967
Sikorsky R-4B (s/n 43-46506) at the National Museum of the U.S. Air Force. Donated to the museum by the University of Illinois in 1967.

Sikorsky R-4 during World War II
Sikorsky R-4 during World War II.

Sikorsky YR-4B during World War II
Sikorsky YR-4B during World War II.

YR-4 equipped with pontoons for shipboard operation, World War II.
YR-4 equipped with pontoons for shipboard operation, World War II.