[5] The XR-4 completed a 761 mi (1,225 km) cross-country flight from Bridgeport, Connecticut, to Wright Field, Ohio, set a helicopter peak altitude record of 12,000 ft (3,700 m), while achieving 100 flight hours without a major incident and top airspeed approaching 90 mph (78 kn; 145 km/h)[6][7] The British Admiralty, having learned of the VS-300, made a ship available, Empire Mersey, fitted with an 80 ft × 40 ft (24 m × 12 m) landing platform, intended to show the USN their work with ship-borne autogyros.

United Aircraft announced on 5 November 1944 that the one hundredth helicopter had been completed, and that the production rate had reached five every six days.

[10] Following the explosion and sinking in January 1944 of USS Turner, U.S. Coast Guard Commander Frank Erickson flew the first U.S. helicopter rescue in a Sikorsky R-4 carrying life saving blood plasma for the casualties from New York City.

[11] On 22–23 April 1944, U.S. Army Lieutenant Carter Harman of the 1st Air Commando Group conducted the first combat rescue by helicopter using a YR-4B in the China-Burma-India theater.

The ships had been configured as floating repair depots for damaged Army Air Forces aircraft in the South Pacific.

[15] Helicopter pilot 2LT Louis Carle was assigned to the Brigadier General Clinton W. Russell, the Fifth Aircraft Repair Unit.

From June 15 to July 29, 1945, Carle and five other pilots evacuated 75 to 80 wounded soldiers, one or two at a time, from the highlands northeast of Manila.

[16] On June 15, 1945, the Fifth Air Force received a request from the 38th Infantry Division to evacuate two soldiers with head injuries from a spot 35 miles (56 km) east of Manila.

Many RAF Hoverfly Mark Is were transferred to the Royal Navy for training and one was used in 1945–46 by Fairey Aviation to develop rotor systems for their Gyrodyne helicopter.

There was no governor to control rotor speed, and the pilot had to correlate the throttle continuously with collective pitch inputs.