Tag Archives: Boeing B-17 Flying Fortress

17 August 1943

Boeing B-17F Flying Fortresses of the 1st Bombardment Wing (Heavy) over Schweinfurt, Germany, 17 August 1943. (U.S. Air Force)

17 August 1943: Mission No. 84. One year after the Eighth Air Force first attacked occupied Europe with its B-17 Flying Fortress four-engine heavy bombers, a mass attack of 376 B-17s attacked the Messerschmitt Bf-109 factory at Regensburg, Germany, and the ball bearing factories at Schweinfurt.

Over Germany for over two hours without fighter escort, 60 bombers were shot down and as many as 95, though they made it to bases in Allied territory, were so badly damaged that they never flew again. 55 air crews (552 men) were listed as missing in action.

Of the 146 B-17s of the 4th Bombardment Wing which attacked Regensburg, 126 dropped their bombs, totaling 298.75 tons (271.02 Metric tons), destroying the factory and seriously slowing the production of the Messerschmitt Bf 109 fighter. After the attack, the 4th Bomb Wing headed for bases in North Africa. 122 B-17s landed there, half of them damaged.

The 1st Bombardment Wing (Heavy) sent 230 B-17s to Schweinfurt. Weather delays caused the planned diversion of two separate attacks to be unsuccessful. Cloud buildup over the Continent forced the bombers to fly at 17,000 feet (5,182 meters), nearly 10,000 feet (3,048 meters) lower than planned, increasing their vulnerability. Just 183 bombers made it to the target and dropped 424.3 tons (383.9 Metric tons) on the five factories in the target area. Then they headed back to their bases in England, under fighter attack most of the way. The 1st Bombardment Wing lost 36 bombers.

Though the raid did cut production of ball bearings as much as 34%, the losses were quickly made up from stockpiles. The two attacking forces succeeded in shooting down 25–27 German fighters.

A B-17 Flying Fortress, its right wing shot off and the left outboard engine on fire, goes down over Europe. (U.S. Air Force)

© 2017, Bryan R. Swopes

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1 August 1939

The flight crew of the FAI World Altitude Record-setting Boeing Y1B-17A. Left to right: Captain Pearl H. Robey, Captain Clarence S. Irvine and R. Swofford. (FAI)

1 August 1939: Captains Clarence S. Irvine and Pearl H. Robey, United States Army Air Corps, used the Boeing Y1B-17A Flying Fortress (Model 299F), serial number 37-369, to set a Fédération Aéronautique Internationale (FAI) World Record for Altitude with a 5,000 Kilogram Payload. The bomber climbed to 34,026 feet with a payload of 11,023 pounds.¹

On the same day, Irvine and Robey flew the Y1B-17 from Dayton, Ohio to St. Jacob, Illinois, setting an FAI World Record for Speed Over 1,000 Kilometers with a 5,000 Kilogram Payload, averaging 417.46 kilometers per hour (259.40 miles per hour).²

The flight crew of the FAI World Speed Record-setting Boeing Y1B-17A. Left to Right: Capatain C.J. Crane, P.G. Miller, Captain Clarence S. Irvine and Captain pearl H. Robey. (FAI)
The flight crew of the FAI World Speed Record-setting Boeing Y1B-17A. Left to Right: Captain Carl J. Crane, P.G. Miller, Captain Clarence S. Irvine and Captain Pearl H. Robey. (FAI)

The single Y1B-17A (Boeing Model 299F) was originally ordered as a static test aircraft, but when that was determined to be unnecessary, it was then used as an engine test aircraft. It was equipped with four 1,823.129-cubic-inch-displacement (29.875 liter) air-cooled, supercharged, Wright R-1820-51 (Cyclone G59) single-row nine-cylinder radial engines. Moss/General Electric turbo-superchargers were installed, initially on top of the wings, but were moved to the bottom of the engine nacelles.

Boeing Y1B-17A 37-369. (FAI)

The supercharged Wright R-1820-39 (Cyclone R-1820-G5) engines of the YB-17s were rated at 805 horsepower at 2,100 r.p.m., at Sea Level, 775 horsepower at 14,000 feet (4,267 meters), and 930 horsepower at 2,200 r.p.m., for take off. By contrast, the YB-17A’s R-1820-51 engines were rated at 800 horsepower at 2,100 r.p.m. at Sea Level, and 1,000 horsepower at 2,200 r.p.m. for take off. But the turbochargers allowed the engines to maintain their sea level power rating all the way to 25,000 feet (7,620 meters). Both the -39 and -51 engine had a 16:11 propeller gear reduction ratio. The R-1820-51 was 3 feet, 9.06 inches (1.145 meters) long, 4 feet, 6.12 inches (1.375 meters) in diameter, and weighed 1,200.50 pounds (544.54 kilograms). 259 were produced by Wright between September 1937 and February 1940.

Boeing Y1B-17A 37-269. (U.S. Air Force)

The turbo-superchargers installed on the YB-17A greatly improved the performance of the bomber, giving it a 55 mile per hour (89 kilometer per hour) increase in speed over the supercharged YB-17s, and increasing the bomber’s service ceiling by 7,000 feet (2,132 meters). The turbo-superchargers worked so well that they were standard on all following B-17 production models.

Boeing Y1B-17A 37-369. (U.S. Air Force photo)

The Boeing Y1B-17A was 68 feet, 9 inches (20.955 meters) long with a wingspan of 103 feet, 9–3/8 inches (31.633 meters) and height of 14 feet, 11–5/16 inches (4.363 meters). Its empty weight was 26,520 pounds (12,029 kilograms). The maximum gross weight was 45,650 pounds (20,707 kilograms)

The Model 299F had a cruise speed of 230 miles per hour (370 kilometers per hour), a maximum speed of 271 miles per hour (436 kilometers per hour) at Sea Level and 295 miles per hour (475 kilometers per hour) at 25,000 feet (7,620 meters). The service ceiling was 38,000 feet (11,582 meters). The maximum range was 3,600 miles (5,794 kilometers). Carrying a 4,000 pound (1,814 kilogram) load of bombs, the range was 2,400 miles (3,862 kilometers).

The Y1B-17A could carry eight 600 pound (272 kilogram) bombs in an internal bomb bay. Defensive armament consisted of five .30-caliber machine guns.

Following the engine tests, 37-369 was re-designated B-17A.

The Boeing Y1B-17A in flight near Mt. Rainier on 28 February 1938. (U.S. Air Force)

¹ FAI Record File Number 8318

² FAI Record File Number 10443

© 2017, Bryan R. Swopes

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28 July 1935

Boeing Model 299, NX13372, photographed during its first flight, 28 July 1935. (The Boeing Company)
Boeing Model 299 NX13372, photographed during its first flight, 28 July 1935. (The Boeing Company)
Boeing test pilot Les Tower. (Boeing)
Boeing’s Chief Test Pilot Leslie R. Tower.

28 July 1935, At Boeing Field, Seattle, Chief Test Pilot Leslie Ralph (“Les”) Tower and Louis Waite took off on the maiden flight of the Boeing Model 299, NX13372, a prototype four-engine long range heavy bomber. For approximately one-and-a-half hours, Tower flew back and forth between Tacoma and Fort Lewis. When he landed, he said, “It handles just like a little ship—a little bigger, of course.”

The Boeing Model 299 was designed to meet a U.S. Army Air Corps proposal for a multi-engine bomber that could carry a 2,000 pound (907 kilogram) bomb load a distance of 2,000 miles (3,219 kilometers) at a speed greater than 200 miles per hour (322 kilometers per hour). Design of the prototype began in June 1934 and construction was started 16 August 1934. The Air Corps designated it B-299, and later, XB-17. It did not carry a military serial number, being marked with civil registration NX13372.

The Boeing Model 299 with Mount Rainier. (U.S. Air Force)
The Boeing Model 299 with Mount Rainier. (U.S. Air Force)

The Model 299 was 68 feet, 9 inches (20.955 meters) long with a wingspan of 103 feet, 9–3/8 inches (31.633 meters) and height of 14 feet, 11–5/16 inches (4.554 meters). Its empty weight was 21,657 pounds (9,823 kilograms). The maximum gross weight was 38,053 pounds (17,261 kilograms).

The prototype was powered by four air-cooled, supercharged, 1,690.537-cubic-inch-displacement (27.703 liter) Pratt & Whitney Hornet S1E-G nine-cylinder radial engines with a compression ratio of 6.5:1. The S1E-G was rated at 750 horsepower at 2,250 r.p.m., and 875 horsepower at 2,300 r.p.m. for takeoff, using 87-octane gasoline. They turned 11 foot, 6 inch (3.505 meters) diameter, three-bladed Hamilton Standard Hydromatic 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)

Boeing Model 299. (U.S.  Air Force)

In flight testing, the Model 299 had a cruise speed of 204 miles per hour (328 kilometers per hour) and a maximum speed of 236 miles per hour (380 kilometers per hour) at 10,000 feet (3,048 meters). The service ceiling was 24,620 feet (7,504.2 meters). Its maximum range was 3,101 miles (4,991 kilometers). Carrying a 2,573 pounds (1,167 kilograms) load of bombs, the range was 2,040 miles (3,283 kilometers).

Boeing 299 NX13372, all engines running.
Boeing 299 NX13372, all engines running.

The XB-17 could carry eight 500 pound (226.8 kilogram) bombs in an internal bomb bay. Defensive armament consisted of five air-cooled Browning .30-caliber machine guns.

Nose turret of the Boeing Model 299, photographed 24 July 1935. (U.S. Air Force)
Nose turret of the Boeing Model 299, photographed 24 July 1935. (The Boeing Company)

NX13372 was destroyed when it crashed on takeoff at Wright Field, Dayton, Ohio, 30 October 1935. An Army Air Corps pilot making his first familiarization flight neglected to remove the control locks. This incident led directly to the creation of the ”check list” which is used by all aircraft crew members.

Waist gun position of the Boeing 299. (U.S. Air force)
Waist gun position of the Boeing 299. (The Boeing Company)

Designated XB-17 by the Army Air Corps, this airplane and the YB-17 pre-production models that followed would undergo several years of testing and improvement before entering production as the B-17 Flying Fortress, a legendary airplane of World War II. By the end of the war 12,731 B-17s had been built by Boeing, Douglas and Lockheed Vega.

Boeing Model 299 NX13372, designated XB-17, at Wright Field, Ohio, 1935. (U.S. Air Force)
Boeing Model 299 NX13372, designated XB-17, at Wright Field, Ohio, 1935. (U.S. Air Force)

© 2017, Bryan R. Swopes

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16 July 1935

The Boeing 299 is rolled out for the first time, 16 July 1935. (Boeing photograph via Seattle Post-Intelligencer)

16 July 1935: Just over a year after design began, the Boeing Model 299, NX13372, a prototype four engine long range heavy bomber, was rolled out of its hangar at Boeing Field, Seattle, Washington for the first time. The largest land airplane built up to that time, it seemed to have defensive machine guns aimed in every direction. A Seattle Times reporter, Roland Smith, wrote that it was a “flying fortress.” Boeing quickly copyrighted the name.

After several years of testing, the Model 299 went into production as the B-17 Flying Fortress. By the end of World War II, 12,731 B-17 Flying Fortresses had been built by Boeing, Douglas and Lockheed Vega.

Rollout of teh Boeing Model 299, NX13372, prototype XB-17. (Museum of Science and Industry)
Rollout of the Boeing Model 299, NX13372, prototype XB-17. (Museum of Science and Industry via Seattle Post-Intelligencer)

The Boeing Model 299 was a four-engine bomber operated by a crew of eight. It was designed to meet a U.S. Army Air Corps proposal for a multi-engine bomber that could carry a 2,000 pound (907 kilogram) bomb load a distance of 2,000 miles (3,219 kilometers) at a speed greater than 200 miles per hour (322 kilometers per hour). Design of the prototype began in June 1934 and construction was started 16 August 1934. The Air Corps designated it B-299, and later, XB-17. It did not carry a military serial number, being marked with civil registration NX13372.

The Model 299 was 68 feet, 9 inches (20.955 meters) long with a wingspan of 103 feet, 9–3/8 inches (31.633 meters) and height of 14 feet, 11–5/16 inches (4.554 meters). Its empty weight was 21,657 pounds (9,823 kilograms). The maximum gross weight was 38,053 pounds (17,261 kilograms).

The prototype was powered by four air-cooled, supercharged, 1,690.54-cubic-inch-displacement (27.703 liter) Pratt & Whitney Hornet S1E-G nine-cylinder radial engines which were rated at 750 horsepower at 2,250 r.p.m., each, and 875 horsepower at 2,300 r.p.m. for takeoff. They turned 11 foot, 6 inch (3.505 meters) diameter, three-bladed Hamilton Standard Hydromatic 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)

Cockpit of the Boeing Model 299. (U.S. Air Force)
Cockpit of the Boeing Model 299. (U.S. Air Force)

In flight testing, the Model 299 had a cruise speed of 204 miles per hour (328 kilometers per hour) and a maximum speed of 236 miles per hour (380 kilometers per hour) at 10,000 feet (3,048 meters). The service ceiling was 24,620 feet (7,504.2 meters). The maximum range was 3,101 miles ( kilometers). Carrying a 2,573 pounds (1,167 kilograms) load of bombs, the range was 2,040 miles (3,283 kilometers).

The XB-17 could carry eight 500 pound (227 kilogram) bombs in an internal bomb bay. Defensive armament consisted of five air-cooled .30-caliber Browning machine guns.

NX13372 was destroyed when it crashed on takeoff at Wright Field, Dayton, Ohio, 30 October 1935. An Army Air Corps pilot making his first familiarization flight neglected to remove the control locks. This incident led directly to the creation of the “check list” which today is used by all aircraft crew members.

Boeing Model 299, NXxxx72, the prototype XB-17. (U.S. Air Force)
Boeing Model 299, NX13372, the prototype XB-17. (U.S. Air Force)
Boeing Model 299 NX13372, designated XB-17, at Wright Field, Ohio, 1935. (U.S. Air Force)
Boeing Model 299 NX13372, designated XB-17, at Wright Field, Ohio, 1935. (U.S. Air Force)

© 2016, Bryan R. Swopes

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12 May 1938

U.S. Army Air Corps YB-17 Flying Fortresses numbers 80 and 82 fly alongside SS Rex, 620 nautical miles east of Sandy Hook, 12 May 1938. (Photograph by Major George W. Goddard, U.S. Army Air Corps)
Major General Frank M. andrews present the Distinguished Flying Cross to Colonel Robert Olds. (U.S. Air Force)
Major General Frank M. Andrews presents the Distinguished Flying Cross to Colonel Robert Olds. (U.S. Air Force)

12 May 1938: Three Boeing B-17 Flying Fortress four-engine bombers of the 49th Bombardment Squadron, 2nd Bombardment Group, departed Mitchel Field, Long Island, New York in heavy rain and headed eastward over the Atlantic Ocean. Their mission, assigned by Major General Frank M. Andrews, commanding General Headquarters, U.S. Army Air Corps, was to locate and photograph the Italian passenger liner, SS Rex, then on a transatlantic voyage to New York City. The purpose was to demonstrate the capabilities and effectiveness of long-range bombers.

The flight was led by Major Caleb V. Haynes, commanding officer of the 49th Bombardment Squadron, flying B-17 number 80. The 2nd Bomb Group commanding officer, Lieutenant Colonel Robert Olds, was aboard Haynes’ B-17, along with an NBC radio crew to broadcast news of the interception live across the country. Reporters from the New York Times and the New York Herald Tribune were aboard the other airplanes.

1st Lieutenant Curtis E. LeMay, U.S. Army Air Corps.
1st Lieutenant Curtis E. LeMay, U.S. Army Air Corps.

The planning of the interception and in-flight navigation was performed by First Lieutenant Curtis E. LeMay. Position reports from SS Rex were obtained and forwarded to LeMay as the aircraft were taxiing for takeoff. The flight departed Mitchel Field at 8:45 a.m. They encountered heavy rain, hail, high winds and poor visibility, but at 12:23 p.m., the Flying Fortresses broke out of a squall line and the passenger liner was seen directly ahead. They flew alongside the ship at 12:25 p.m., 620 nautical miles (1,148.24 kilometers) east of Sandy Hook, New York. They were exactly on the time calculated by Lieutenant LeMay. The B-17s made several passes for still and motion picture photography while NBC broadcast the event.

Colonel Olds would rise to the rank of Major General and command 2nd Air Force during World War II. He was the father of legendary fighter pilot Brigadier General Robin Olds. Major Hayes served in various combat commands and retired at the rank of Major General in 1953.

Curtis LeMay would be a Major in command of the 305th Bombardment Group, a B-17 unit, at the beginning of World War II. He personally led many combat missions over Europe, and would command the 4th Bombardment Wing and then the 3rd Air Division. By the end of the war, he was in command of the XXI Bomber Command based in the Marianas Islands. From 1948 to 1957, General LeMay commanded the Strategic Air Command, then served as Vice Chief of Staff of the Air Force. From 1961 to 1965, LeMay was Chief of Staff.

At the time of the interception of the Rex, there were only 12 B-17s in the Air Corps inventory: the original Y1B-17 development aircraft. By the end of production in 1945, 12,731 B-17 Flying Fortresses had been built by three aircraft manufacturers.

Boeing YB-17 Flying Fortress 36-149. (U.S. Air Force)
Boeing Y1B-17 Flying Fortress 36-149. (U.S. Air Force)

The Boeing B-17 (Model 299B, previously designated Y1B-17, and then YB-17) was a pre-production service test prototype. Thirteen had been ordered by the Air Corps. It was 68 feet, 4 inches (20.828 meters long with a wingspan of 103 feet, 9 inches (31.633 meters) and the overall height was 18 feet, 4 inches (5.588 meters).

The YB-17 was powered by four air-cooled, supercharged 1,823.129-cubic-inch-displacement (29.876 liter) Wright Aeronautical Division Cyclone R-1820G5 (R-1820-39) nine-cylinder radial engines with a compression ratio of 6.45:1. The R-1820-39 had a Normal Power rating of 805 horsepower at 2,100 r.p.m. at Sea Level, and 930 horsepower at 2,200 r.p.m. for Takeoff, burning 92-octane gasoline. A long carburetor intake on top of the engine nacelles visually distinguishes the YB-17 from the follow-on YB-17A. The engines drove three-bladed Hamilton Standard constant-speed propellers through a 16:11 gear reduction. The R-1820-39 was 3 feet, 9-7/16 inches (1.154 meters) long and 4 feet, 6¼ inches (1.378 meters) in diameter. It weighed 1,198 pounds (543.4 kilograms).

Boeing YB-17 36-149. (U.S. Air Force)
Boeing YB-17 36-149. (U.S. Air Force)

The YB-17 had an empty weight of 24,465 pounds (11,097 kilograms), gross weight of 34,880 pounds (15,821 kilograms) and maximum takeoff weight of 42,600 pounds (19,323 kilograms). The maximum speed was 256 miles per hour (412 kilometers per hour) at 14,000 feet (4,267 meters). Its service ceiling was 30,600 feet (9,327 meters) and the maximum range was 3,320 miles (5,343 kilometers).

The YB-17 could carry 8,000 pounds (3,629 kilograms) of bombs. Defensive armament consisted of five air-cooled Browning .30-caliber machine guns.

Boeing YB-17 36-149. (U.S. Air Force)
Boeing YB-17 36-149. (U.S. Air Force)

© 2017, Bryan R. Swopes

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