The USAAF and RAF Vought-Sikorsky R-4 Hoverfly was the worlds first production helicopter and was used during World War Two operationally. That was news to me. I did not realize we used helicopters during WW2. I thought the first war they were utilized in was the Korean war. I was wrong. The Sikorsky R-4 was called the 'Hoverfly One' by the Royal Air Force (RAF) and Royal navy. It was the first type of helicopter to enter service with the British Military. 52 R-4s were operated by the British.

The Sikorsky R4 pioneered nearly every role of rotary winged helicopter flying and paved the way for all other helicopters that went after it. Whilst underpowered it could do all the basic tasks of modern helicopters. It had two seats and a single, three-bladed main rotor and powered by a radial engine. It had a top speed of only 75mph (120 km/h) with a cruise speed of 65 mph ( 105km/h) It could only fly up to 8,000ft (2,400m)

Vought-Sikorsky division of United Aircraft were awarded the contract to develop a two-seat version helicopter based on their working prototype in the spring of 1941. It was designated Rotorcraft XR- 4 by the United States Army Air Forces. It first flew in January 1942.

The Sikorsky R-4 Helicopter was the first helicopter to land aboard a ship. The British Royal Navy having learned of the R-4 helicopter, made one of their ships available. They had intended to show the United States Navy their work with autogyros but helicopters sounded more promising. The Empire Mersey was fitted with a landing platform. After her loss in 1942 to a U-boat, she was replaced by the SS Daghestan. The British navy received two of the first eight helicopters built.

The Sikorsky R-4 Helicopter was the first helicopter to effect a rescue when on 23rd April 1944 in Burma it evacuated 4 persons from a crashed aircraft in Japanese territory. It was flown by U.S. Army Lieutenant Carter Harman. He picked up an American downed liaison aircraft pilot and his three British soldier passengers, two at a time. It was also used to ferry parts between floating Aviation Repair Units in the South Pacific. Some of the R4 Hoverfly MK1s were fitted with pontoon floats for landing on water.

Sikorsky Aircraft Corporation was founded in 1925 by aircraft engineer Igor Sikorsky, a Kiev-born American immigrant. It is an American company based in Stanford Connecticut though they now have bases all over the US. The U.S. Navy and U.S. Coast Guard operated Twenty-five R-4s, under the designation HNS-1. It was the first helicopter produced for the U.S. Army and more than 400 were produced by the end of WWII. It saw service in the India - Burma - China theatre of war against the Japanese.

The R-4 Helicopter was not quite ready for serious military field use. The Hoverfly had limited performance and payload. Hot days caused problems. On one flight demonstration to USAAF top brass simply refused to leave the ground. Despite the R4's limitations, it quickly demonstrated the value of the helicopter by the military, performing a number of rescues and emergency deliveries under field conditions in the last year of the war