Tag Archives: World War II

17 May 1943

The crew of the Memphis Belle after their 25th mission: (left to right) Technical Sergeant Harold Loch, Top Turret Gunner/Engineer; Staff Sergeant Cecil Scott, Ball Turret Gunner; Technical Sergeant Robert Hanson, Radio Operator; Captain James Verinis, Co-pilot; Captain Robert Morgan, Aircraft Commander/Pilot; Captain Charles Leighton, Navigator; Staff Sergeant John Quinlan, Tail Gunner; Staff Sergeant Casimer Nastal, Waist Gunner; Captain Vincent Evans, Bombardier; Staff Sergeant Clarence Winchell Waist Gunner. (U.S. Air Force photograph)

17 May 1943: The flight crew of the B-17 Memphis Belle completed their combat tour of 25 bombing missions over Western Europe with an attack on the massive Kéroman Submarine Base at Lorient, France. ¹ The bomber was a U.S. Army Air Force Boeing B-17F-10-BO Flying Fortress, serial number 41-24485, assigned to the 324th Bombardment Squadron (Heavy), 91st Bombardment Group (Heavy), VIII Bomber Command, based at Air Force Station 121 (RAF Bassingbourne, Cambridgeshire, England). The aircraft commander was Captain Robert Knight Morgan, Air Corps, United States Army.

The daylight bombing campaign of Nazi-occupied Europe was extremely dangerous with high losses in both airmen and aircraft. For an Amereican bomber crew, 25 combat missions was a complete tour, and then they were sent back to the United States for rest and retraining before going on to other assignments. Memphis Belle was only the second B-17 to survive 25 missions, so it was withdrawn from combat and sent back to the United States for a publicity tour.

Miss Margaret Polk
Miss Margaret Polk

The B-17′s name was a reference to Captain Morgan’s girlfriend, Miss Margaret Polk, who lived in Memphis, Tennessee. The artwork painted on the airplane’s nose was a “Petty Girl,” based on the work of pin-up artist George Petty of Esquire magazine. ²

(Morgan named his next airplane—a B-29 Superfortress—Dauntless Dotty, after his wife, Dorothy Grace Johnson Morgan. With it, he led the first B-29 bombing mission against Tokyo, Japan, in 1944. It was also decorated with a Petty Girl.)

Memphis Belle and her crew were the subject of a 45-minute documentary, “Memphis Belle: A Story of a Flying Fortress,” directed by William Wyler and released in April 1944. It was filmed in combat aboard Memphis Belle and several other B-17s. The United States Library of Congress named it for preservation as a culturally significant film.

B-17F-10-BO Flying Fortress 41-24485 (c/n 3190) was built by the Boeing Aircraft Company at its Plant 2 in Seattle, Washington, during the summer of 1942. It was the 195th airplane in the B-17F series, and one of the third production block. Flown by a Boeing pilot named Johnston, the new bomber made its first flight, 1 hour, 40 minutes, on 13 August 1942. Maintenance records indicate, “1st flight OK.”

The B-17 was flown to Bangor, Maine and on 31 August 1942 was assigned to the 324th Bombardment Squadron (Heavy), 91st Bombardment Group (Heavy), then preparing to deploy overseas.

2nd Lieutenant Morgan first flew 41-24485 on 3 September, and logged nearly 50 hours over the next three weeks. The squadron flew across the North Atlantic Ocean, and 41-24485 arrived at its permanent station, Bassingbourne, on 26 October 1942.

Following its twenty-fifth combat mission, Memphis Belle was flown back to the United States on 9 June 1943.

After the war, Memphis Belle was put on display in the city of Memphis. For decades it suffered from time, weather and neglect. The Air Force finally took the bomber back and placed it in the permanent collection of the National Museum of the United States Air Force at Wright-Patterson Air Force Base, Dayton, Ohio, where it underwent a total restoration.

Survivors. The crew of the Memphis belle after their 25th combat mission, 17 May 1943. (U.S. Air Force)
Survivors. The crew of the Memphis Belle after their 25th combat mission, 17 May 1943. (U.S. Air Force)

The Boeing B-17F Flying Fortress was a four-engine heavy bomber operated by a flight crew of ten. It was 74 feet, 8.90 inches (22.781 meters) long with a wingspan of 103 feet, 9.375 inches (31.633 meters) and an overall height of 19 feet, 1.00 inch (5.187 meters). The wings have 3½° angle of incidence and 4½° dihedral. The leading edge is swept aft 8¾°. The total wing area is 1,426 square feet (132.48 square meters). The horizontal stabilizer has a span of 43 feet (13.106 meters) with 0° incidence and dihedral. Its total area, including elevators, is 331.1 square feet (12.18 square meters).

The B-17F had an approximate empty weight of 36,135 pounds (16,391 kilograms), 40,437 pounds (18,342 kilograms) basic, and the maximum takeoff weight was 65,000 pounds (29,484 kilograms).

The B-17F was powered by four air-cooled, supercharged, 1,823.129-cubic-inch-displacement (29.876 liters) Wright Cyclone G666A (R-1820-65) ³ nine-cylinder radial engines with a compression ratio of 6.70:1. The engines were equipped with remote General Electric  turbochargers capable of 24,000 r.p.m. The R-1820-65 was rated at 1,000 horsepower at 2,300 r.p.m. at Sea Level, and 1,200 horsepower at 2,500 r.p.m. for takeoff. The engine could produce 1,380 horsepower at War Emergency Power. 100-octane aviation gasoline was required. The Cyclones turned three-bladed, constant-speed, Hamilton-Standard Hydromatic propellers with a diameter of 11 feet, 7 inches (3.835 meters) though a 0.5625:1 gear reduction. The R-1820-65 engine is 3 feet, 11.59 inches (1.209 meters) long and 4 feet, 7.12 inches (1.400 meters) in diameter. It weighs 1,315 pounds (596 kilograms).

Boeing B-17F-10-BO Flying Fortress 41-22485, Memphis Belle, in flight over England, 1943. (U.S. Air Force)

The B-17F had a cruising speed of 200 miles per hour (322 kilometers per hour). The maximum speed was 299 miles per hour (481 kilometers per hour) at 25,000 feet (7,620 meters), though with War Emergency Power, the bomber could reach 325 miles per hour (523 kilometers per hour) at 25,000 feet for short periods. The service ceiling was 37,500 feet (11,430 meters).

The original “Petty Girl” pin-up nose art of the B-17 bomber, “Memphis Belle,” during restoration.

With a normal fuel load of 1,725 gallons (6,530 liters) the B-17F had a maximum range of 3,070 miles (4,941 kilometers). Two “Tokyo tanks” could be installed in the bomb bay, increasing capacity by 820 gallons (3,104 liters). Carrying a 6,000 pound (2,722 kilogram) bomb load, the range was 1,300 miles (2,092 kilometers).

The Memphis Belle was armed with 13 Browning AN-M2 .50-caliber machine guns for defense against enemy fighters. Power turrets mounting two guns each were located at the dorsal and ventral positions. Four machine guns were mounted in the nose, 1 in the radio compartment, 2 in the waist and 2 in the tail.

The maximum bomb load of the B-17F was 20,800 pounds (9434.7 kilograms) over very short ranges. Normally, 4,000–6,000 pounds (1,815–2,722 kilograms) of high explosive bombs were carried. The internal bomb bay could be loaded with a maximum of eight 1,600 pound (725.75 kilogram) bombs. Two external bomb racks mounted under the wings between the fuselage and the inboard engines could carry one 4,000 pound (1,814.4 kilogram) bomb, each, though this option was rarely used.

The B-17 Flying Fortress was in production from 1936 to 1945. 12,731 B-17s were built by Boeing, Douglas Aircraft Company and Lockheed-Vega. (The manufacturer codes -BO, -DL and -VE follows the Block Number in each airplane’s type designation.) 3,405 of the total were B-17Fs, with 2,000 built by Boeing, 605 by Douglas and 500 by Lockheed-Vega.

Boeing B-17F-10-BO Flying Fortress 41-24485, Memphis Belle, flies home from England, 9 June 1943. (U.S. Air Force)

Only three B-17F Flying Fortresses, including Memphis Belle, remain in existence. The completely restored bomber went on public display at the National Museum of the United States Air Force on 17 May 2018.

Boeing B-17F-10-BO Flying Fortress 41-24485, “Memphis Belle,” photographed 14 March 2018 at the National Museum of the United States Air Force, Wright-Patterson Air Force Base, Ohio. (U.S. Air Force)

Memphis Belle ® is a Registered Trademark of the United States Air Force.

¹ VIII Bomber Command Mission No. 58

² The nose art was painted by Corporal Anthony L. Starcer.

³ Later production B-17F and B-17G bombers were equipped with Wright Cyclone C9GC (R-1820-97) engines.

Boeing B-17F-10-BO Flying Fortress 41-24485, “Memphis Belle,” photographed 14 March 2018 at the National Museum of the United States Air Force, Wright-Patterson Air Force Base, Ohio. (U.S. Air Force)

© 2018, Bryan R. Swopes

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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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15 May 1942

B-24E-1-FO Liberator 42-6976, the first B-24 heavy bomber to come off the assembly line at Willow Run, 15 May 1942. (The Henry Ford THF25680 Ford Motor Co. Willow Run Bomber Plant)
B-24E-1-FO Liberator 42-6976, the first B-24 heavy bomber to come off the assembly line at Willow Run, 15 May 1942. (The Henry Ford THF25680 Ford Motor Co. Willow Run Bomber Plant)

15 May 1942: The first Ford-built B-24 Liberator long range heavy bomber came off the assembly line at the Willow Run Airplane Plant, just 160 days after the United States entered World War II. 6,971 B-24s more would follow, along with assembly kits for another 1,893, before production came to an end, 28 June 1945.

The first Ford-built B-24 Liberator in final assembly at the Willow Run Airplane Plant, 12 May 1942. (Ford)
The first Ford-built B-24 Liberator in final assembly at the Willow Run Airplane Plant, 12 May 1942. (Ford)
B-24E-1-FO Liberator 42-6976, the first B-24 heavy bomber to come off the assembly line at Willow Run, 15 May 1942. (The Henry Ford THF25680 Ford Motor Co. Willow Run Bomber Plant)
B-24E-1-FO Liberator 42-6976, the first B-24 heavy bomber to come off the assembly line at Willow Run, 15 May 1942. (The Henry Ford THF25680 Ford Motor Co. Willow Run Bomber Plant)
Willow Run
The Ford Motor Company Willow Run Airplane Plant
A Willow Run-built B-24E Liberator long range heavy bomber, 1942. (Ford Motor Company)

© 2018, Bryan R. Swopes

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9 May 1944

Martin B-26B-25-MA Marauder 41-31819, “Mild and Bitter,” photographed during its 50th combat mission. (American Air Museum in Britain FRE 1191)

9 May 1944: A Martin B-26B Marauder of the 442nd Bombardment Squadron, 322 Bombardment Group, Ninth Air Force, named Mild and Bitter, landed at RAF Bury St. Edmunds, a military airfield in Suffolk, England. When its engines had stopped, it had  completed its second combat mission of the day: an attack against an enemy airfield at Évreaux-Fauville, in the Normandy region of France.

This was the one-hundredth combat mission flown by Mild and Bitter. It had flown 310 hours, 40 minutes in combat.

In those 100 missions, the airplane had never been forced to abort for mechanical reasons, it always came back with both of its engines running, never came back with its bomb load, and most importantly, of the 166 airmen who had flown aboard, none had ever been wounded or killed.

The bomber still had the two Pratt & Whitney Double Wasp engines which had been installed at the factory, having logged 449 hour, 30 minutes, total time since new (TTSN).

The 100th mission flight crew of Martin B-26B Marauder 41-31819, “Mild and Bitter.” Left to right, 1st Lt. L.W. Rice; 2nd Lt. H.R. Harp; Capt. P. Shannon; SSgt. W.J. Bond; Sgt. R.E. Johnson, SSgt. J.K. Brandemihl. (U.S. Air Force)
Captain Paul Shannon

The flight crew for the Marauder’s final mission was Captain Paul Shannon, aircraft commander; First Lieutenant Lee W. Rice, co-pilot; Second Lieutenant Harry R. Harp, bombardier/navigator; Staff Sergeant James K. Brandemihl, flight engineer and top turret gunner; Staff Sergeant Walter J. Bond, radio operator; and Sergeant Robert E. Johnson, tail gunner.

Following this last mission. 41-31819 was returned to the United States as part of a War Bonds tour. Following that, the B-26 was

. . . taken to Patterson Field for study. inspection, and possible salvage.

Daily Hampshire Gazette Wed 26 July 1944

Martin B-26B-25-MA Marauder 41-31819, “Mild and Bitter,” following its 100th combat mission, May 1944. (American Air Museum in Britain FRE 4477)

FIRST HUNDRED

     Just before dark, the sleek, fast B-26 Marauder circled her English air base and slipped in to a smooth landing. Technical Sergeant William L. Stuart, a taciturn, red-haired Texan, heaved an eloquent sigh, rubbed his grease-stained hands together, got out his tools and prepared to go to work.

     The ship rolling up to his dispersal station, the “Mild & Bitter,” had just made history: she was back from her 100th combat mission. Sergeant Stuart, her crew chief, had sweated out every one of the 100 for her; now he would check her over and get her ready for Mission 101. “Mild & Bitter” thus joined the select company of famed warplanes of World War II—planes like the embattled Fortresses “Memphis Belle” and “Hell’s Angels,” and the R.A.F.’s Lancaster “S for Sugar.”

Quiet Type

     But “Mild & Bitter” had no record of hair-raising escapes. Her saga was one of good luck and almost monotonous efficiency. She had lugged 166 different airmen to battle; 26 were decorated, but not one got a Purple Heart. During her robust career she acquired some 50 flak holes, but never any damage that Bill Stuart and his ground crew could not repair overnight.

     On her first combat flight, last July 28, she led a sweep over Abbeville; the 100th mission was to bomb an airfield at Evreux, near Paris. In between she had taken the targets as they came; power plants, E-boat pens, air bases, all around France up to Holland and back. She still had her original Pratt & Whitney, 2000 Hp engines. No one had picked any soft spots for the ship, even when she neared her record. Her last two missions were done between dawn and sunset, her last four in 36 hours.

Successful Type

     Ninth Air Force men were proud of “Mild & Bitter,” proud also that her performance so well underlined the striking success in the European Theater of the whole B-26 Marauder type. Once regarded by many airmen as a hot and dangerous aircraft, the B-26 has proved to be the outstanding medium bomber of the European air war. Its combat losses (less than 0.3%) are the lowest in the theater.

     Crew Chief Stuart (who named the plane after hearing Englishmen ordering their pints of mild & bitter in a local pub) tried hard to think of something spectacular that had happened to the ship. On one raid, it is true, a burst of flak fountained up right through the open bomb bay. Hot steel fragments rattled against cold steel bombs with a hellish din. But nothing happened.

     The record of the B-26 is equally good in all other theaters of operations.

TIME Magazine, 22 May 1944, reprinted in Pilot Training Manual for the B-26, Headquarters, AAF, Office of Flying Safety, Page 7

Martin B-26B Marauder 41-31819, Mild and Bitter, 322nd Bombardment Group. (American Air Museum in Britain FRE 4478)

Mild and Bitter was a Martin B-26B-25-MA Marauder twin-engine medium bomber, U.S. Army Air Forces serial number 41-31819. It had been built by the Glenn L. Martin Company at Middle River, Maryland, in 1943. It was 58 feet, 2 inches (17.729 meters) long, with a wingspan of 71 feet, 0 inches (21.641 meters), and overall height of 21 feet, 6 inches (6.553 meters). The wings had a total area of 664.1 square feet (61.7 square meters). Their angle of incidence was 3° 30′ and they had 1° 17′ dihedral. The stabilizer had a span of 28 feet, 0 inches (8.534 meters), with -5° incidence and 8° dihedral. The bomber had an empty weight of 24,000 pounds (10,886 kilograms) and gross weight of 37,000 pounds (16,783 kilograms).

Crew Chief with Martin B-26B-25-MA Marauder 41-31819, DR-X, (American Air Museum in Britain UPL 28017)

The B-26B-25-MA was powered by two air-cooled, supercharged, 2,804.461-cubic-inch-displacement (45.956 liter), Pratt & Whitney Double Wasp 2SB-G (R-2800-41) two-row, 18-cylinder radial engines with a compression ratio of 6.65:1. The R-2800-41 had a Normal Power rating of 1,600 horsepower at 2,400 r.p.m. to 5,700 feet (1,737 meters), and 1,450 horsepower at 2,400 r.p.m. at 13,000 feet (3,962 meters). Its Takeoff Power rating was 2,000 horsepower at 2,700 r.p.m. The Military Power rating was the same as Takeoff Power up to 2,700 feet (823 meters), and 1,600 horsepower at 2,700 r.p.m. to 13,500 feet (4,115 meters). They turned 13 foot, 6 inch (4.115 meter) diameter four-bladed Curtiss Electric constant-speed, full-feathering propellers through a 2:1 gear reduction. The R-2800-41 was 6 feet, 3.72 inches (1.923 meters) long, 4 feet, 4.50 inches (1.334 meters) in diameter, and weighed 2,300 pounds (1,043 kilograms).

The B-26B had a maximum speed of 270 miles per hour (435 kilometers per hour) at Sea Level, and 282 miles per hour (454 kilometers per hour) at 15,000 feet (4,572 meters). The airplane’s service ceiling was 21,700 feet (6,614 meters). It’s maximum ferry range was 2,850 miles (4,587 kilometers).

The B-26B was armed with 11 air-cooled Browning AN-M2 .50-caliber machine guns. One was at the nose on a flexible mount, two fixed guns were on each side of the nose in “blister packs,” there were two flexible guns in the waist. A Martin power-operated dorsal gun turret had two, as did the remote Bell hydraulically-operated gun mount in the tail.

A maximum of four 2,000 pound (907 kilograms) bombs could be carried in the bomb bay.

When the B-26 entered service, it quickly gained a reputation as a dangerous airplane and was called “the widowmaker.” The airplane had relatively short wings with a small area for its size. This required that landing approaches be flown at much higher speeds than was normal practice. With one engine out, airspeed was even more critical. Some changes were made, such as a slight increase on wingspan and the size of the vertical fin and rudder, and an emphasis was made on airspeed control during training. The Marauder had the lowest rate of combat losses of any American bomber.

The Glenn L. Martin Co. produced 5,288 Marauders between 1941–1945. It served in the Pacific, Mediterranean and European combat areas. When it was removed from service at the end of World War II, the “B-26” designation was reassigned to the Douglas A-26 Invader, a twin-engine light bomber.

41-31819 (26955 A.C.) AAMiB UPL 28011

© 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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