Sikorsky R-4

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The Sikorsky R-4 was the world's first production helicopter and the United States Air Force'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 XR-4 made its initial flight on January 13, 1942 and as a result of its successful flight tests, the United States Army Air Forces ordered 3 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 United States Navy, United States Coast Guard and British 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.

The R4 showed such promise that the AAF ordered 100 R-4Bs. It was first used in combat in May 1944. In a letter to a friend, Col. Philip G. Cochran, Commanding Officer (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."

R-4 Museum displays

• 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

Specifications (R-4B)

• Rotor diameter: 38 ft (11.5 m)
• Length: 33 ft 7 3/4 in (10.2 m)
• Height: 12 ft 5 in (3.8 m)
• Weight: 2,581 lb (1170 kg) loaded
• Armament: None
• Engine: Warner R-550 - 200 hp. (149 kW)

• Maximum speed: 75 mph (120 km/h)
• Cruising speed: 65 mph (105 km/h)
• *Service Ceiling: 8,000 ft (2400 m)

External links

• [Sikorsky R-4 page at the National Museum of the United States Air Force]
• [RAF Museum Sikorsky R4 Hoverfly webpage]

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