Tag Archives: Vought-Sikorsky Aircraft Division

17 May 1942

Sikorsky XR-4 41-18874 at Wright Field, Ohio, 17 May 1942. (Sikorsky Historical Archives)
Vought-Sikorsky XR-4 41-18874 at Wright Field, Ohio, 17 May 1942. (Sikorsky Historical Archives)
The Sikorsky XR-4 41-18874 at Wright Field, 17 May 1942. Left to right: E. Walsh, A. Planefisch, Igor Sikorsky, Orville Wright, R. Alex, Les Morris, B. Labensky. (Sikorsky Archives)

17 May 1942: After a 761 mile (1,224.7 kilometer) flight over five days, test pilot Charles Lester (“Les”) Morris and Igor Sikorsky arrived at Wright Field, Dayton, Ohio, to deliver the U.S. Army’s first helicopter, the Vought-Sikorsky XR-4. Morris hovered directly up to the base administration building and landed there. He and Sikorsky were greeted by a large group of people which included Lieutenant Colonel Hollingsworth Franklin (“Frank”) Gregory, the Army’s designated rotorcraft expert, and pioneer aviator Orville Wright.

From the Sikorsky factory at Stratford, Connecticut, to Wright Field, Ohio, was 761 miles (1,224.7 kilometers), direct. Because of the XR-4’s low speed and short range (weight limitations restricted the quantity of gasoline it could carry) the distance was covered in sixteen separate flights with a total flight time of 16 hours, 10 minutes. The longest single flight lasted 1 hour, 50 minutes, a new world’s record for helicopter flight endurance. Igor Sikorsky joined Les Morris for the final leg of the flight.

Sikorsky test pilot Charles Lester (“Les”) Morris in the cockpit of an earlier version of the Vought-Sikorsky VS-300. (Hans Groenhoff Photographic Collection, Smithsonian Institution National Air and Space Museum NASM-HGC-1408)

The Vought-Sikorsky VS-316A (which was designated XR-4 by the U.S. Army Air Corps and assigned serial number 41-18874), established the single main rotor/anti-torque tail rotor configuration. It was a two-place helicopter with side-by-side seating and dual flight controls. The fabric-covered three-blade main rotor was 38 feet (11.582 meters) in diameter and turned counter-clockwise as seen from above. (The advancing blade is on the helicopter’s right). The three-blade tail rotor was mounted to the right of the tail boom in a tractor configuration, and rotated clockwise when seen from the helicopter’s left side. (The advancing blade was below the axis of rotation.)

The XR-4 was 33 feet, 11.5 inches (10.351 meters) long and 12 feet, 5 inches (3.785 meters) high. It weighed 2,010 pounds (911.7 kilograms) empty and the maximum gross weight was 2,540 pounds (1,152.1 kilograms).

The VS-316A had originally been powered by a 499.8-cubic-inch-displacement (8.19 liter) air-cooled Warner Aircraft Corporation Scarab SS-50 (R-500-1) seven-cylinder radial engine, rated at 145 horsepower at 2,050 r.p.m. In the XR-4 configuration, the engine was upgraded to an air-cooled, direct-drive 555.298-cubic-inch-displacement (9.100 liter) Warner Super Scarab SS185 (R-550-3) seven-cylinder radial engine with a compression ration of 6.20:1. The R-550-3 was rated at 185 horsepower at 2,175 r.p.m. at Sea Level, and 200 horsepower at 2,475 r.p.m (five minute limit) for takeoff. The engine was placed backwards in the aircraft with the propeller shaft driving a short driveshaft through a clutch to a 90° gear box and the transmission. The R-550-3 weighed 344 pounds (156 kilograms).

The XR-4 was redesignated XR-4C. This would be the world’s first production helicopter. It is at the Steven F. Udvar-Hazy Center of the Smithsonian National Air and Space Museum.

Vought-Sikorsky XR-4C 41-18874 at the National Air and Space Museum. (NASM)

© 2019, Bryan R. Swopes

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6–7 May 1943

Colonel Frank Gregory lands the Vought-Sikorsky XR-4, 41-18864, aboard SS Bunker Hill, 6-7 May 1943. (Sikorsky Historical Archives)
Colonel Frank Gregory lands the Vought-Sikorsky XR-4, 41-18874, aboard SS Bunker Hill, 6-7 May 1943. (Sikorsky Historical Archives)

6–7 May 1943: To determine the feasibility of operating helicopters from the decks of merchant ships for antisubmarine patrols, Colonel Hollingsworth Franklin (“Frank”) Gregory, U.S. Army Air Corps, made 23 landings and takeoffs from the tanker SS Bunker Hill in Long Island Sound, flying the Army’s Vought-Sikorsky XR-4, 41-18874.

According to an official U.S. Coast Guard history of the tests,

The tanker BUNKER HILL was made available for the tests and a deck 78 feet [23.8 meters] long, with obstructions at both ends, was put in place. An eight foot [2.4 meters] bullseye in the center of a square was painted in the middle of the platform. Colonel Frank Gregory arrived on 6 May to fly the Army XR-4 provided for the tests. The entire helicopter project rested on the XR-4’s ability to land on a ship. Gregory was concerned at first. His “shipboard” experience was limited to a 20 foot [6.1 meters] platform at Wright Field. He immediately set about getting “additional experience.” Gregory noted with reference to his first attempt:

Igor Sikorsky and Colonel Frank Gregory with the Vought-Sikorsky XR-4. (Sikorsky Historical Archives)
Igor Sikorsky and Colonel Frank Gregory with the Vought-Sikorsky XR-4. (Sikorsky Historical Archives)

“The space on the deck looked even smaller—it didn’t look like the helicopter would fit. The cabin superstructure towered up like a two story building, and the people on it had that “it can’t be done” look on their faces—yet the big white bullseye stuck out like a target—the XR-4 came true to the white marker as though being pulled by a powerful magnet, and a minute later the floats touched the deck.”

He continued to practice landings and takeoffs that afternoon with the ship at anchor, then underway at five, seven and one-half, ten and fifteen knots. As the speed increased the landings became more difficult because of increased turbulence over the superstructure but the helicopter proved to be completely controllable.

The next morning guests were ferried out to the BUNKER HILL . . . A total of 97 names were on the guest list. Gregory put on an impressive and flawless performance as the ship cruised at various speeds up to 15 knots and on various headings with relation to the wind which was blowing at 12 knots. . . .

—”The Helicopter as an Anti-Submarine Weapon,” A History of Coast Guard Aviation, The Growth Years (1939–1956).

SS Bunker Hill, a Type T2 tanker, with a tugboat alongside. (Unattributed)
SS Bunker Hill, a Type T-2 tanker, with a tugboat alongside. (Unattributed)

SS Bunker Hill was a 10,590 gross ton Type T-2 tanker owned by the Keystone Tankship Corporation. It was  504 feet (153.6 meters) long, with a beam of 68.2 feet (20.8 meters) and drawing 39.2 feet (12 meters). Its engine developed 7,000 horsepower.

On 6 March 1964, Bunker Hill was enroute from Tacoma to Anacortes, Washington when it suffered a vapor explosion in the Number 9 cargo tank which broke the ship in half. It sank in Rosario Strait in less than one hour. Five members of the crew of thirty-one, including the captain, chief mate, third mate, quartermaster and steward, were lost.

The Vought-Sikorsky VS-316A (which was designated XR-4 by the U.S. Army Air Corps and assigned serial number 41-18874), established the single main rotor/anti-torque tail rotor configuration. It was a two-place helicopter with side-by-side seating and dual flight controls. The fabric-covered three-blade main rotor was 38 feet (11.582 meters) in diameter and turned counter-clockwise as seen from above. (The advancing blade is on the helicopter’s right). The three-blade tail rotor was mounted to the right of the tail boom in a tractor configuration, and rotated clockwise when seen from the helicopter’s left side. (The advancing blade was below the axis of rotation.)

The XR-4 was 33 feet, 11.5 inches (10.351 meters) long and 12 feet, 5 inches (3.785 meters) high. It weighed 2,010 pounds (911.7 kilograms) empty and the maximum gross weight was 2,540 pounds (1,152.1 kilograms).

The VS-316A had originally been powered by a 499.8-cubic-inch-displacement (8.19 liter) air-cooled Warner Scarab SS-50 (R-500-1) seven-cylinder radial engine, rated at 145 horsepower at 2,050 r.p.m. In the XR-4 configuration, the engine was upgraded to an air-cooled, direct-drive 555.298-cubic-inch-displacement (9.100 liter) Warner Super Scarab SS185 (R-550-3) seven-cylinder radial engine with a compression ration of 6.20:1. The R-550-3 was rated at 185 horsepower at 2,175 r.p.m. at Sea Level, and 200 horsepower at 2,475 r.p.m (five minute limit) for takeoff. The engine was placed backwards in the aircraft with the propeller shaft driving a short driveshaft through a clutch to a 90° gear box and the transmission. The R-550-3 weighed 344 pounds (156 kilograms).

The XR-4 was redesignated XR-4C. This would be the world’s first production helicopter. It is at the Steven F. Udvar-Hazy Center of the Smithsonian National Air and Space Museum.

Vought-Sikorsky XR-4 41-18874 during shipboard testing, June 1943. (Sikorsky Historical Archives)
Vought-Sikorsky XR-4 41-18874 during shipboard testing, June 1943. (Sikorsky Historical Archives)

© 2019, Bryan R. Swopes

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21–25 April 1944

First Lieutenant Carter Harman, United States Army Air Corps. (U.S. Army)
Second Lieutenant Carter Harman, United States Army Air Corps. (U.S. Army)

21 April 1944: The first military helicopter combat rescue began with Lieutenant Carter Harman, 1st Air Commando Group, being ordered to proceed from Lalaghat, India with his Vought-Sikorsky YR-4B, 43-28247, 600 miles (965 kilometers) to Taro in northern Burma.

Technical Sergeant Ed “Murphy” Hladovcak, pilot of a Stinson L-1A Vigilant liaison airplane, had crashed in the jungle behind Japanese lines while transporting three wounded British soldiers. Lieutenant Harman was assigned to attempt to rescue the four men. It would be a marathon operation.

The first Stinson O-49 liaison airplane, 40-192. The type was redesignated L-1A Vigilant in April 1942. (U.S. Air Force)
The first Stinson O-49 liaison airplane, 40-192. The type was redesignated L-1A Vigilant in April 1942. The L-1A was expensive to manufacture, but had excellent short field performance. (U.S. Air Force)

It took Harman and his Sikorsky 24 hours to arrive at Taro. After a brief rest and dip in the river to cool off, he continued for another 125 miles (202 kilometers) to an airstrip in the jungle called “Aberdeen” which was well behind the enemy lines. It was from here that Sgt. Hladovcak had been operating, flying out wounded soldiers. From Aberdeen, Harman was led to the location of the downed men by another liaison airplane. The survivors were surrounded by Japanese soldiers who had found the crashed airplane and were trying to locate the four men.

Lt. Carter Harman hovering in ground effect with Sikorsky YR-4B Hoverfly 43-28247 at Lalaghat, India, March 1944. This is the helicopter with which he made the first combat rescue, 21–25 April 1944. (U.S. Air Force)
Lt. Carter Harman hovering in ground effect with Sikorsky YR-4B 43-28247 at Lalaghat, India, March 1944. This is the helicopter with which he made the first combat rescue, 21–25 April 1944. (U.S. Air Force)

Because of the high heat, elevation and humidity, which increased the density altitude, the YR-4B’s air-cooled engine was unable to produce its full rated power. Also, the helicopter’s rotor blades were not as effective as they would have beeen at lower density altitudes.

Harman planned to lift one of the survivors out of the clearing in the jungle and fly a short distance to a sand bank where other L-1 or L-5 liaison airplanes could pick them up and fly them back to Aberdeen. He would repeat the operation until all four men had been rescued. However, it took the rest of the day to airlift just the first two wounded and very sick soldiers.

Distinguished Flying Cross

On the second flight, the helicopter’s engine was overheating and on landing it seized and could not be restarted. Sergeant Hladovcak and the remaining soldier were still in the jungle, Lieutenant Harman was stuck by the river bank and Japanese soldiers were everywhere.

On the morning of 25 April Lieutenant Harman was able to get the helicopter’s engine to start, and again, one at a time, he rescued the two remaining survivors. A liaison plane flew out the wounded soldier while Hladovcak rode along with Harman back to Aberdeen. He had never seen a helicopter before.

For his actions, Lieutenant Carter Harman was awarded the Distinguished Flying Cross.

Sikorsky YR-4B 43-28247 was condemned 31 December 1944.

Lieutenant Carter Harman (standing, left), 1st Air Commando Group, with Sikorsky YR-4B-8-SI 43-28223, Burma, 26 April 1944. (U.S. Air Force)
Lieutenant Carter Harman, 1st Air Commando Group, (standing, left) with Sikorsky YR-4B 43-28223, Burma, 26 April 1944. The other officer standing next to Harman is Lieutenant Frank Peterson. Harman’s crew chief, Sergeant Jim Phelan, is kneeling at right. (U.S. Air Force)

The Sikorsky YR-4B was a two-place, single-engine helicopter with a single main rotor and an anti-torque tail rotor. The fuselage was 35 feet, 8.375 inches (10.881 meters) long with a main rotor diameter of 38 feet, 0 inches (11.582 meters). The tail rotor was 8 feet, 2.25 inches (2.496 meters) in diameter. Its overall length, with rotors turning, was 48 feet, 3.375 inches (4.716 meters). The helicopter had an overall height of 12 feet, 5 inches (3.785 meters). The empty weight was 2,020 pounds (916 kilograms) and maximum takeoff weight of 2,540 pounds (1,152 kilograms). The helicopter’s fuel capacity was 30 gallons (113.6 liters)

The main rotor consisted of three tapered, fully-articulated blades built of chrome-molybdenum steel spars and spruce plywood ribs, with laminated spruce, balsa and mahogany forming the leading edge and a flexible cable forming the trailing edge. The blades were covered with two layers of doped fabric. The three-bladed semi-articulated tail rotor was built with a spruce spar and alternating laminations of maple and mahogany, covered with fabric. Both the main and tail rotors had a thin brass abrasion strip covering the leading edges. 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 right side in a tractor configuration. It turned clockwise as seen from the helicopter’s left. (The advancing blade is below the axis of rotation.)

Lieutenant Carter Harmon in the cockpit of Sikorsky YR-4B 43-28223, Burma, 1945.

The YR-4B was powered by an air-cooled, direct-drive 555.298-cubic-inch-displacement (9.100 liter) Warner Super Scarab SS185 (R-550-3) seven-cylinder radial engine with a compression ratio of 6.20:1. The R-550-3 was rated at 185 horsepower at 2,175 r.p.m. at Sea Level, and 200 horsepower at 2,475 r.p.m (five minute limit) for takeoff. The engine was placed backwards in the aircraft with the propeller shaft driving a short driveshaft through a clutch to a 90° gear box and the transmission. The R-550-3 weighed 344 pounds (156 kilograms).

The R-4B had a cruise speed of 65 miles per hour (105 kilometers per hour) and maximum speed of 82 miles per hour (132 kilometers per hour). The service ceiling was 12,000 feet (3,658 meters) and range was 157 miles (253 kilometers).

The YR-4B was equipped with bomb racks. It could carry three 125 pound (56.7 kilogram) demolition bombs or one 325 pound (147 kilogram) depth bomb. The equipment was deleted for the R-4B.

Sikorsky built 27 YR-4Bs and 100 R-4B helicopters. Of these, 40 were assigned to the Army Air Corps, 19 to the Navy and Coast Guard, and 41 were sent to the Royal Air Force and Royal Navy.

Sikorsky YR-4B 43-28225 in the NACA full scale wind tunnel, Langley Field, Virginia, 1944. A technician is preparing strobes to take stop-motion photographs of the helicopter's rotor blades while they turn at normal operating r.p.m. (NASA)
Sikorsky YR-4B 43-28225 in the NACA full scale wind tunnel, Langley Field, Virginia, 1944. A technician is preparing strobes to take stop-motion photographs of the helicopter’s rotor blades while they turn at normal operating r.p.m. (NASA)

Carter Harman was born at Brooklyn, New York, 14 June 1918, the son of Steven Palmer Harman, a newspaper editor, and Helen F. Doremus Harman.

Before the war, Harman had been a musician and author. He assisted Duke Ellington write an autobiography. Harman earned a bachelor’s degree in music composition from Princeton University, Princeton, New Jersey, in 1940. While at Princeton, Harman was a member of the Dial Lodge, American Whig Society, Princeton University Band, and the Princeton University Choir.

Harman enlisted as a private in the United States Army at Hew York City on 1 April 1942, and was assigned to the Air Corps. Enlistment records indicate that he was 5 feet, 7 inches (170.2 centimeters) tall and weighed 125 pounds (57 kilograms).

After World War II ended, Harman returned to his musical studies at Columbia University, New York City, receiving a master’s degree in 1949.

Harman worked as a music critic for The New York Times and Time Magazine, and also continued writing books, as well as composing for ballet and opera. He was also a music producer and became executive vice president of CRI Records (Composers Recordings, Inc.).

Harman was married three times. He married Miss Nancy Hallinan, 5 February 1946, however they later divorced. His second wife was Helen Scott. They had four children together. His third wife was Wanda Maximilien.

Carter Harman died at Berlin, Vermont, 23 January 2007 at the age of 88 years.

© 2018, Bryan R. Swopes

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30 March 1934

Sikorsky S-42 NC822M, Brazilian Clipper, first of three of the initial S-42 variant. (NASM)

30 March 1934: At Bridgeport, Connecticut, Sikorsky Aircraft Company test pilot Boris Vasilievich Sergievsky made the first flight of the prototype Sikorsky S-42, a large, four-engine flying boat which had been designed for long range passenger and cargo flights.

In discussions with Igor Sikorsky, Charles A. Lindbergh, acting as technical advisor to Pan American Airways System, the two aviation icons established the specifications for a new flying boat. The new airplane would be a significant improvement over Sikorky’s previous S-40.

The Hartford Courant report:

New Giant Sikorsky Tries Its Wings

Sikorsky S-42 (Associated Press Photo)

     Bridgeport.  March 30.—(AP)—America’s greatest passenger plane, the S-42, destined for the South American service, took to the air for the first time and passed two test flights with flying colors.

     Once for 10 minutes, and again for a longer period, the giant flying boat hovered over Long Island Sound and its shore. Captain Boris Sergievsky, accompanied only by a lone mechanic, was at the controls.

     “Congratulations, sir,” Igor Sikorsky, designer of the plane, hailed the pilot as he came ashore after the flights.

     “The congratulations,” Captain Sergievsky replied, “are yours, sir.”

     “I am very pleased with the results,” Sikorsky said. “It was most thrilling to see the ship take off. Everything seems excellent.”

     Frederick W. Neilsen, president of the Sikorsky Aviation Corporation, who watched the flights with Sikorsky and hundreds of residents of Bridgeport and shore towns, said, “The tests were most successful and we are all pleased.”

     The ship, built for Pan American Airways on specifications by Colonel Charles A. Lindbergh, technical advisor for the line, is the first of six such planes to be completed for Pan American.

     Powered with four engines, it is 76 feet long, has a span of 114 feet 2 inches, and a gross weight of 38,000 pounds. It will be fitted with 32 passenger seats, and will have a non-stop range of 1200 miles with a full complement of passengers, five members of the crew and 1000 pounds of mail.

The Hartford Courant, Vol. XCVII, Saturday, 31 March 1934, Page 18, Columns 4 and 5

Interior of a Sikorsky S-42. (NASM)

The Sikorsky S-42 was a four-engine long-range flying boat built for Pan American Airways by the Vought-Sikorsky Aircraft Division of United Technologies at Stratford, Connecticut. It was 67 feet, 8 inches (20.625 meters) long with a wingspan of 114 feet, 2 inches (34.798 meters). The S-42 had an empty weight of 18,236 pounds (8,272 kilograms) and gross weight of 38,000 pounds (17,237 kilograms). It could carry up to 37 passengers.

A Pan American Airways Sikorsky S-42.

The S-42 was powered by four air-cooled, supercharged, 1,690.537-cubic-inch-displacement (27.703 liters) Pratt & Whitney Hornet S1E-G nine-cylinder radial engines with a compression ratio of 6.5:1. The S1E-G had a Normal Power rating of 750 horsepower at 2,250 r.p.m., to 7,000 feet (2,134 meters), and 875 horsepower at 2,300 r.p.m., for Takeoff. The engines drove three-bladed Hamilton Standard constant-speed propellers through a 3:2 gear reduction. The S1E-G was 4 feet, 1.38 inches (1.254 meters) long, 4 feet, 6.44 inches (1.383 meters) in diameter, and weighed 1,064 pounds (483 kilograms).

Boris Vasilievich Sergievsky

The S-42 had a cruise speed 165 miles per hour (266 kilometers per hour) and maximum speed of 188 miles per hour (303 kilometers per hour) at 5,000 feet (1,524 meters). The service ceiling was 16,000 feet (4,877 meters). It could maintain 7,500 feet (2,286 meters) with three engines. Its range was 1,930 miles (3,106 kilometers).

During flight testing of the S-42, Boris Sergievsky, with co-pilot Raymond B. Quick, set three Fédération Aéronautique Internationale world records for payload and altitude.¹  Later, Captain Edwin Musick, with Sergievsky and Charles Lindbergh, flew the S-42 to set eight Fédération Aéronautique Internationale world records for speed.²

Ten Sikorsky S-42, S-42A and S-42B flying boats were built for Pan Am. None remain in existence.

A Pan American Airways Sikorsky S-42, NC16742, moored at Honolulu, Territory of the Hawaiian Islands. (hawaii.gov/hawaiiaviation)

¹ 26 April 1934 FAI Record File Numbers: 11583: Greatest load to 2,000 meters (6,562 feet): 7,533 kilograms (16,652 pounds). 17 May 1934: 11582 and 11978: Altitude with a 5,000 Kilogram (11,023 pounds) Load, 6,220 meters (20,407 feet).

² 1 April 1934 FAI Record File Numbers: 11517: Speed over a closed circuit of 1,000 Kilometers (621.3 statute miles), 253,60 km/h (157.58 m.p.h.); 11518: . . . with a 500 Kilogram (1,102 pounds) Payload, 253,60 km/h (157.58 m.p.h.); 11519: . . . with a 1,000 Kilogram (2,205 pounds) Payload, 253,60 km/h (157.58 m.p.h.); 11520: . . . with a 2,000 kilogram (4,409 pounds) Payload, 253,60 km/h (157.58 m.p.h.); 11521: Speed over a closed circuit of 2,000 Kilometers (1,242.7 statute miles), 253,18 km/h (157.32 m.p.h); 11522: . . . with a 500 Kilogram Payload, 253,18 km/h (157.32 m.p.h.); 11523: . . . with a 1,000 Kilogram Payload, 253,18 km/h (157.32 m.p.h.); 11524: . . . with a 2,000 Kilogram Payload, 253,18 km/h (157.32 m.p.h.).

© 2019, Bryan R. Swopes

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14 January 1942

Les Morris at the controls of the Vought-Sikorsky VS-316A (XR-4, serial number 41-18874) on its first flight at Stratford, Connecticut, 13 January 1942. (SikorskyHistorical Archives)
Les Morris at the controls of the Vought-Sikorsky VS-316A (XR-4, serial number 41-18874) on its first flight at Stratford, Connecticut, 14 January 1942. (Sikorsky Historical Archives)

14 January 1942: Chief Test Pilot Charles Lester (“Les”) Morris (1908–1991) made the first flight of the Vought-Sikorsky VS-316A at Stratford, Connecticut. The first flight lasted approximately 3 minutes, and by the end of the day, Morris had made 6 flights totaling 25 minutes duration.

“One-half left front close-up head-and-shoulders view of test pilot Charles L. “Les” Morris posed seated in the cockpit of the Sikorsky VS-300 helicopter (r/n NX28996), March 29, 1943.” (Hans Groenhoff Photographic Collection, Smithsonian Institution National Air and Space Museum NASM-HGC-1408

The VS-316A (which was designated XR-4 by the U.S. Army Air Corps and assigned serial number 41-18874), established the single main rotor/anti-torque tail rotor configuration. It was a two-place helicopter with side-by-side seating and dual flight controls.

The fabric-covered three-blade main rotor was 38 feet (11.582 meters) in diameter and turned counter-clockwise as seen from above. (The advancing blade is on the helicopter’s right.) The tail rotor was mounted to the aft end of the tail boom in a tractor configuration, and rotated counter-clockwise when seen from the helicopter’s right side.

The VS-316A was 33 feet, 11.5 inches (10.351 meters) long and 12 feet, 5 inches (3.785 meters) high. It weighed 2,010 pounds (911.7 kilograms) empty and the maximum gross weight was 2,540 pounds (1,152.1 kilograms).

The original engine installed in the VS-316A was an air-cooled, normally-aspirated, 499.805-cubic-inch-displacement (8.190 liter) Warner Aircraft Corporation Scarab SS-50 seven-cylinder radial  engine with a compression ratio of 5.55:1. The SS-50 was a direct-drive engine, with a maximum continuous power rating of 109 horsepower at 1,865 r.p.m., and 145 horsepower at 2,050 r.p.m. at Sea Level for takeoff. 73-octane gasoline was required. The SS50 was 2 feet, 5 inches (0.737 meters) long, 3 feet, 0-9/16 inches (0.929 meters) in diameter and weighed 306 pounds (139 kilograms).

gor Ivanovich Sikorsky and Charles Lester Morris with the XR-4 at Wright Field, Ohio, May 1942. (Sikorsky Historical Archives)
Orville Wright and Igor Ivanovich Sikorsky with the XR-4 at Wright Field, Ohio, May 1942. (Sikorsky Historical Archives)

Numerous modifications were made, including lengthening the main rotor blades, covering them with metal, and upgrading the engine to a 200 horsepower Warner R-550-1 Super Scarab. The XR-4 was redesignated XR-4C. This would be the world’s first production helicopter. It is at the Steven F. Udvar-Hazy Center of the Smithsonian National Air and Space Museum.

Sikorsky XR-4C 41-18874 at the National Air and Space Museum. (NASM)
Sikorsky XR-4C 41-18874 at the National Air and Space Museum. (NASM)

© 2019, Bryan R. Swopes

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