The Sikorsky R4 was a twoseat helicopter designed by Igor Sikorsky with a single, threebladed main rotor and powered by a radial engine. The R4 was the world's first largescale massproduced helicopter and the first helicopter used by the United States Army Air Forces, the United States Navy, the United States Coast Guard and the United Kingdom's Royal Air Force and Royal Navy. In U.S. Navy and U.S. Coast Guard service, the helicopter was known as the Sikorsky HNS1. (In British service, it was known as the Hoverfly.)

The R4 began as the VS316, which was developed from the famous experimental VS300 helicopter, invented by Igor Sikorsky and publicly demonstrated in 1940. The VS316 was designated the XR4 under the United States Army Air Forces' series for "Rotorcraft" and is the aircraft the army is proudly showing off in this 1942 film.

The XR4 first flew on 14 January 1942 and was accepted by the Army on 30 May 1942. The XR4 exceeded all the previous helicopter endurance, altitude and airspeed records that had been set before it. The XR4 completed a 761mile (1,225 km) crosscountry flight from Connecticut to Wright Field, Ohio, set a service ceiling record of 12,000 feet (3,700 m), while achieving 100 flight hours without a major incident and an airspeed approaching 90 mph (140 km/h).