The prototype VS-300 helicopter clears the ground for the first time, 14 September 1939. Igor Sikorsky is at the controls. His right foot rests on the anti-torque pedal. (Sikorsky Historical Archives)
14 September 1939: At Stratford, Connecticut, Igor Sikorsky made the first tethered flight of the Vought-Sikorsky VS-300 prototype helicopter. The duration of the flight was just 10 seconds but demonstrated that the helicopter could be controlled.
The Vought-Sikorsky VS-300 was the first successful single main rotor, single tail rotor helicopter.
The three-bladed main rotor had a diameter of 28 feet (8.534 meters) and turned approximately 255 r.p.m. The rotor turned clockwise as seen from above (the advancing blade is on the left). This would later be reversed. A counter-weighted single blade anti-torque rotor with a length of 3 feet, 4 inches (1.016 meters) is mounted on the left side of the monocoque beam tail boom in a pusher configuration and turns counter-clockwise as seen from the helicopter’s left (the advancing blade is above the axis of rotation).
Vought-Sikorsky VS-300 under construction, 8 September 1939. (Sikorsky Historical Archives)
In the initial configuration, the VS-300 was powered by an air-cooled, normally-aspirated, 144.489-cubic-inch-displacement (2.368 liter) Lycoming O-145-C3 horizontally-opposed, four-cylinder, direct-drive engine with a compression ratio of 6.5:1. It was rated at 75 horsepower at 3,100 r.p.m., using 73-octane gasoline. It was equipped with a single Stromberg carburetor and dual Scintilla magnetos. The dry weight of the O-145-C3 was 167 pounds (75.75 kilograms). Later in the VS-300’s development, the Lycoming was replaced by a 90-horsepower Franklin 4AC-199 engine.
On 19 December 1939, the VS-300 was rolled over by a gust of wind and damaged. It was rebuilt, however, and developed through a series of configurations. It made its first free (untethered) flight 13 May 1940.
Test flights continued for several years. After 102 hours, 32 minutes, 26 seconds of flight, the VS-300 was donated to the Henry Ford Museum, Dearborn, Michigan.
Igor Sikorsky adjusts his fedora while at the controls of the VS-300. (Sikorsky Historical Archives)
The second Sikorsky XR-5, 43-28237 (c/n 34). (Sikorsky, a Lockheed Martin Company)
18 August 1943: At Bridgeport, Connecticut, Sikorsky chief test pilot Charles Lester (“Les”) Morris made the first flight of the Vought-Sikorsky VS-327, c/n 33. Also known as the Sikorsky Model S-48, the U.S. Army Air Corps designated the helicopter XR-5 and assigned the serial number 43-28236.
The XR-5 was a significant improvement over the earlier R-4. Its narrow fuselage was streamlined and the cockpit had excellent visibility. The R-4’s box-like fuselage interfered with the downward flow of air from the main rotor, and this was a consideration in the shape of the new helicopter.
The Sikorsky XR-5 (Model S-48) was a single-engine, two-place helicopter. The cabin was built of aluminum with plexiglas windows. The fuselage was built of plastic-impregnated plywood and the tail boom was wood monocoque construction. The main rotor consisted of three fully-articulated blades built of wood spars and ribs and covered with fabric. The three bladed semi-articulated tail rotor was built of laminated wood. The main rotor turned counter-clockwise as seen from above. (The advancing blade is on the helicopter’s right.) The tail rotor was mounted on the helicopter’s left side in a pusher configuration. It turned clockwise as seen from the helicopter’s left.
There were five XR-5 helicopters, followed by twenty-six YR-5A service test helicopters built between November 1944 and July 1945. There were slight changes from the earlier five XR-5A prototypes. The R-5A went into production in July 1945 and more than 300 had been built by the time production ended in 1951.
The helicopter’s fuselage was 41 feet, 7½ inches (12.687 meters) long. The main rotor had a diameter of 48 feet (14.630 meters) and tail rotor diameter was 8 feet, 5 inches (2.2.565 meters), giving the helicopter an overall length of 57 feet, 1 inch (17.399 meters) with rotors turning. It was 13 feet, 1½ inches (4.001 meters) high. The landing gear tread was 12 feet (3.7 meters). The R-5A had an empty weight of 3,780 pounds (1,714.6 kilograms) and maximum takeoff weight of 4,900 pounds (2,222.6 kilograms). Fuel capacity was 100 gallons (378.5 liters).
Chief Test Pilot Les Morris with Captain Jackson E. Beighle, U.S. Army Air Corps, hovers a Sikorsky YR-5A, 43-46603, at Bridgeport, with ten additional passengers, 29 November 1945. (Sikorsky, a Lockheed Martin Company)
The helicopter was powered by an air-cooled, supercharged, 986.749-cubic-inch-displacement (16.170 liter) Pratt & Whitney Wasp Jr. T1B4 (R-985 AN-5) direct-drive, nine-cylinder radial engine which was placed vertically in the fuselage behind the crew compartment. This engine was rated at 450 horsepower at 2,300 r.p.m., Standard Day at Sea Level. The R-985 AN-5 was 48.00 inches (1.219 meters) long, 46.25 inches (1.175 meters) in diameter and weighed 684 pounds (310.3 kilograms) with a magnesium crankcase.
The R-5 had a maximum speed (Vne) of 107 knots (123.1 miles per hour/198.2 kilometers per hour). Range was 275 miles (442.6 kilometers). The service ceiling was 14,800 feet (4,511 meters). The absolute hover ceiling was 3,000 feet (914.4 meters).
On 13 September 1943, Dimitry D. (“Jimmy”) Viner was hovering out of ground effect at 75 feet (23 meters) when 43-28236 suffered a tail rotor failure. The helicopter made a hard landing and was dignificantly damaged. Neither Viner nor his passenger were injured.
In 1944, while flying to a war bond rally in Nebraska, XR-5 43-28236 suffered an engine failure and crash landed. The helicopter was damaged beyond repair and was stripped for parts.
Thanks to regular This Day in Aviation reader Mike for suggesting this subject.
Igor Sikorsky in the cockpit of a production R-5 helicopter. (Sikorsky, a Lockheed Martin Company)
