Sikorsky R-4B Hoverfly Developed by Igor Sikorsky from his famous VS-300 experimental helicopter, the R-4 became the world's first production helicopter, and the U.S. Army Air Force's first service helicopter. The prototype XR-4 made its initial flight on Jan. 13, 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, 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. 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." The R-4B on display was donated to the museum by the University of Illinois in 1967. TECHNICAL NOTES: Engine: Warner R-550 of 200 hp Maximum speed: 75 mph Cruising speed: 65 mph Range: 130 miles Ceiling: 8,000 ft. Rotor diameter: 38 ft. Length: 33 ft. 7 3/4 in. Height: 12 ft. 5 in. Weight: 2,581 lbs. loaded Serial number: 43-46506 Click here to return to the World War II Gallery.