Tag Archives: Heavy Bomber

8 August 1946

Convair XB-36 Peacemaker 42-13570 engine run-up
The prototype Consolidated-Vultee XB-36, 42-13570, stands at the end of the runway with all six engines running. (U.S. Air Force)

8 August 1946: At Fort Worth, Texas, the Consolidated-Vultee Aircraft Corporation XB-36 prototype, 42-13570, made its first flight. Convair test pilots Beryl Arthur Erickson and G.S. “Gus” Green, along with Chief Flight Test Engineer James D. “J.D.” McEachern, were in the cockpit. Six other crew members were aboard.

Chief Test Pilot Beryl Arthur Erickson. (Convair)

In a 1992 interview published in Code One Magazine, Erickson said that he and his crew had been ready to take off at 5 a.m., but they didn’t get their release until noon. The Texas summer temperature was 100 degrees (37.8 °C.), but inside the cockpit, the temperature was 140° F. (60 °C.) The engines were overheating and the oil pressure was low. When they pushed the throttles forward, the XB-36 accelerated smoothly and lifted off at 110 knots (126.6 miles per hour, 203.7 kilometers per hour). The retired test pilot said, “The XB-36 controlled nicely in the takeoff run and in the transition to steady climb. We flew conservatively with the gear down. The flight was uneventful and lasted thirty-eight minutes.”

Chief Test Pilot Beryl Arthur Erickson at the aircraft commander’s station of the Consolidated-Vultee XB-36 long-range heavy bomber. (Code One).

The B-36 was the largest and heaviest airplane built up to that time. It was designed as a long-range heavy bomber, able to reach targets on the European continent from the United States and return, should England fall to Nazi Germany during World War II. With the end of the war, its purpose was changed to that of a long range strategic bomber, carrying large nuclear weapons that weren’t even imagined when the design process had begun.

A size comparison between the Convair XB-36 prototype and a Boeing B-29 Superfortress.
A size comparison between a Boeing B-29-55-BA Superfortress, 44-84017, and the Consolidated-Vultee XB-36 prototype, Carswell AFB, June 1948. (U.S. Air Force Historical Research Agency)

The XB-36 had a wing span of 230 feet (70.104 meters), nearly 90 feet longer than that of the B-29 Superfortress that it would replace. It was 162 feet, 1 inch (49.403 meters) long and 46 feet, 8 inches (14.224 meters) to the tip of the vertical fin. The prototype’s empty weight was 131,740 pounds (59,756 kilograms), and it had a maximum gross weight of 276,506 pounds (125,421 kilograms).

The XB-36 was powered by six air-cooled, supercharged, 4,362.49 cubic-inch-displacement (71.489 liter) Pratt & Whitney Wasp Major TSB1P-G (R-4360-25) 28-cylinder four-row radial engines, with a normal power rating of 2,500 horsepower at 2,550 r.p.m. to 5,000 feet (1,524 meters), and 3,000 horsepower at 2,700 r.p.m. for takeoff. They were mounted inside the wings. The engines were arranged in a “pusher” configuration with intake and cooling air entering through inlets in the wing leading edge. They drove three-bladed propellers with a diameter of 19 feet (5.8 meters) through a 0.381:1 gear reduction. The R-4360-25 was 9 feet, 1.75 inches (2.788 meters) long 4 feet, 4.50 inches (1.334 meters) in diameter, and weighed 3,483 pounds (1,580 kilograms).

The airplane’s maximum speed was 346 miles per hour (557 kilometers per hour) and cruising speed was 216 miles per hour (348 kilometers per hour). It had an estimated range of 9,500 miles (15,290 kilometers) with a 10,000 pound (4,536 kilogram) bomb load.

The prototype Convair XB-36, 42-13570, lifts off the runway at Fort Worth, Texas. (U.S. Air Force)
The prototype Consolidated-Vultee XB-36, 42-13570, lifts off the runway at Fort Worth, Texas. (U.S. Air Force)

After testing, improvements were incorporated into the second prototype, YB-36 42-13571. In June 1948, the XB-36 was modified with R-4360-41 engines, and the main landing gear was changed from a single-wheel design to a 4-wheel bogie. With these and other changes the XB-36 was redesignated YB-36A. It was used for continued testing for the next several years, but was eventually stripped of its engines and equipment and used for firefighter training at the adjacent Carswell Air Force Base.

The YB-36 was selected for production as the B-36A Peacemaker. The B-36 series was produced in both bomber and reconnaissance versions and was in front line service from 1949 to 1959. Beginning with the B-36D, four turbojet engines were mounted beneath the wings in pods similar to those on the Boeing B-47 Stratojet, greatly increasing the bomber’s performance. A total of 384 were built. Only five still exist. The Peacemaker was never used in combat.

The Convair XB-36 in flight. (U.S. Air Force)
The Consolidated-Vultee XB-36 prototype, 42-13570, in flight. (U.S. Air Force)

© 2020, Bryan R. Swopes

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 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 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)

Leslie Ralph Tower was born at Sisseton, South Dakota, 21 January 1903. He was the first of three children of Ralph R. Tower, a farmer who would later serve as a state senator for Montana, and Mayme Amanda Johnson Tower, a Swedish immigrant.

Les Tower attended high school at Polson, Montana, graduating in 1922. He then attended the University of Washington, where he studied engineering. He was a member of the Radio Club.

Tower enlisted in the United States Army as an aviation cadet, training at Brooks and Kelly airfields in Texas. He then served with the 2nd Bombardment Squadron at Langley Field, Virginia.

In 1925 Tower started working for Boeing as a draftsman, but soon began test flying new airplanes, which included the B-9 bomber and the Model 247 commercial airliner. He also demonstrated and delivered Boeing airplanes around the world.

On 20 August 1935, Tower and Louis Wait flew the Model 299 from Seattle to Dayton, approximately 2,100 miles, in 9 hours, 3 minutes, averaging 233 miles per hour (375 kilometers per hour).

Les Tower was aboard the XB-17 as an observer during the 30 October flight. He saw that the control locks had not been released and tried to reach them, but was unable. In the fire that followed the crash, Tower suffered severe burns to his face, right arm and both legs.

Leslie Ralph Tower died of his injuries 19 November 1935 at Miami Valley Hospital in Dayton. His remains were transported by train, escorted by Army airplanes, and were buried at Lakeview Cemetery, Polson, Montana.

© 2020, Bryan R. Swopes

30 May 1942

A Boeing B-17F Flying Fortress takes off from Boeing Field, Seattle, Washington, 1942.
A Boeing B-17F Flying Fortress takes off from Boeing Field, Seattle, Washington, 1942.

30 May 1942: The Boeing B-17F Flying Fortress makes its first flight. B-17F-1-BO 41-24340 was the first of a new series of the famous World War II bomber. While visually similar to the B-17E, it had more than 400 improvements based on early wartime experience with the B-17D and B-17E.

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).

Boeing B-17F Flying Fortress
Boeing B-17F-95-BO Flying Fortress 42-30243, near Mount Rainier, Washigton, circa May 1943. Note the underwing bomb racks. It was assigned to the 331st Bombardment Squadron), 94th Bombardment Group (Heavy), marked QE Z, and named “Nip ‘n’ Tuck.” This bomber crashed at Évreaux, Normandy, France, 14 July 1943. 8 crew members were captured, but 2 evaded. (Boeing Airplane Company)

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).

Aircraft mechaincs work to change a Wright Cyclone engine on the left wing of a B-17 Flying Fortress heavy bomber, circa 1944. (United States Air Force)

The B-17F was powered by four air-cooled, supercharged, 1,823.129-cubic-inch-displacement (29.876 liters) Wright Cyclone C9GC (R-1820-97) nine-cylinder radial engines with a compression ratio of 6.70:1. (Early production B-17Fs were equipped with the Wright Cyclone G666A (R-1820-65). Both variants had the same power ratings.) The engines were equipped with remote General Electric B-22 turbochargers capable of 24,000 r.p.m. The R-1820-97 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) through a 0.5625:1 gear reduction. The R-1820-97 engine is 47.80 inches (1.214 meters) long and 55.10 inches (1.399 meters) in diameter. It weighs 1,315 pounds (596 kilograms).

Boeing B-17F-130-BO Flying Fortress 42-30949, “Jumpin’ Jive.” This bomber survived the war. (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).

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).

Most of the .50-caliber machine guns arming the B-17F Flying Fortress are visible in this photograph. (U.S. Air Force)
Many of the .50-caliber machine guns arming the B-17F Flying Fortress are visible in this photograph. (U.S. Air Force)

The B-17F Flying Fortress was armed with up to 13 air-cooled Browning AN-M2 .50-caliber machine guns. Power turrets mounting two guns each were located at the dorsal and ventral positions. A pair of machine guns were mounted in the tail, and single guns on flexible mounts were placed in the nose, radio compartment, and right and left waist positions.

A waist gunner of a B-17 with a Browning .50-caliber machine gun. Note the flight control cables, overhead, and expended cartridge casings. “Body armor saved lives. An 8th Air Force study found that body armor prevented approximately 74 percent of wounds in protected areas. Once adopted in World War II, body armor reduced the rate of wounds sustained by aircrews on missions by 60 percent. Besides saving lives, body armor boosted aircrew morale during stressful missions over enemy territory.” (U.S. Air Force)
A gunner fires the two Browning .50 caliber machine guns of his ball turret. (U.S. Air Force)
Checking the two AN-M2 Browning .50-caliber machine guns at the tail of a Boeing B-17 Flying Fortress heavy bomber, circa 1943. (Note the formation lights below the gun barrels.) LIFE Magazine)

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.

Boeing B-17F-10-BO Flying Fortress 41-22485, Memphis Belle, in flight over England, 1943. (U.S. Air Force)
Probably the best known individual combat airplane, this is Boeing B-17F-10-BO Flying Fortress 41-22485, Memphis Belle, in flight over England, 1943. (U.S. Air Force)

The B-17 Flying Fortress first flew in 1935, and was in production from 1937 to 1945. 12,731 B-17s were built by Boeing, Douglas Aircraft Company and Lockheed-Vega. (The Manufacturer Codes, -BO, -DL and -VE, follow 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.

Only three B-17F Flying Fortresses remain in existence.

This restored Boeing B-17F-70-BO Flying Fortress, 42-29782, is on display at The Museum of Flight at Seattle’s Boeing Field. (Boeing)
This restored Boeing B-17F-70-BO Flying Fortress, 42-29782, (N17W) is on display at The Museum of Flight at Seattle’s Boeing Field. (Boeing)

© 2018, Bryan R. Swopes

11 December 1945

Bell-Atlanta B-29B-60-BA Superfortress 44-84061, the Pacusan Dreamboat. (U.S. Air Force)
Bell-Atlanta B-29B-60-BA Superfortress 44-84061, the Pacusan Dreamboat. (U.S. Air Force)

11 December 1945: Three days after Lieutenant Colonel Henry E. Warden and Captain Glen W. Edwards set a transcontinental speed record flying a prototype Douglas XB-42 from Long Beach, California, to Washington, D.C., in 5 hours, 17 minutes, Colonel Clarence S. Irvine and the crew of the B-29 Pacusan Dreamboat also set a record, flying from Burbank, California to overhead Floyd Bennett Field, New York, in 5 hours, 27 minutes, 8 seconds. The average speed for the 2,464-mile flight was 450.38 miles per hour (724.82 kilometers per hour).

Lieutenant General Clarence S. Irvine, U.S. Air Force

Irvine was Deputy Chief of Staff, Pacific Air Command, 1944–1947. He flew the Pacusan Dreamboat on several record-setting flights, including Guam to Washington, D.C., and Honolulu, Hawaii to Cairo, Egypt. He rose to the rank of lieutenant general in the United States Air Force, and served as Deputy Chief of Staff for Materiel.

Pacusan Dreamboat was a Bell Aircraft Corporation B-29B-60-BA Superfortress, built at Marietta, Georgia. The B-29B was a lightweight variant of the B-29, intended for operation at lower altitudes. It did not have the four power gun turrets and their .50-caliber machine guns. A radar-directed 20 mm cannon and two .50-caliber machine guns in the tail were the only defensive weapons. Much of the standard armor plate was also deleted. Pacusan Dreamboat was further lightened. The tail guns were removed and the tail reshaped.

The B-29B was equipped with four air-cooled, fuel-injected Wright R-3350-CA-2 Duplex Cyclone two-row 18 cylinder radial engines and specially-designed propellers. The engine nacelles were modified for improved cooling.

The Superfortress had been lightened to an empty weight of 66,000 pounds (29,937 kilograms). A standard B-29B weighed 69,000 pounds (31,298 kilograms) empty and 137,000 pounds (62,142 kilograms) fully loaded. Additional fuel tanks installed on the Dreamboat were able to carry 10,000 gallons (37,854 liters) of gasoline.

Colonel Clarence S. Irvine (standing, left) with the crew of Pacusan Dreamboat: W.J.Benett, G.F.Broughton, Dock West, W.S. O’Hara, F.S. O’Leary, K.L. Royer, F.J.Shannon, J.A. Shinnault, G.R. Stanley. (FAI)
Colonel Clarence S. Irvine (standing, left) with the crew of Pacusan Dreamboat: W.J. Benett, G.F. Broughton, Dock West, W.S. O’Hara, F.S. O’Leary, K.L. Royer, F.J. Shannon, J.A. Shinnault, G.R. Stanley. (FAI)

© 2015, Bryan R. Swopes

22 November 1933

Kalinen K-7
К-7 на аэродроме (“K-7 at the airport”), right front quarter view. (Уголок неба)

22 November 1933:

The K-7 Disaster

     On Wednesday, November 22, the Russian aircraft K-7, claimed to be the largest landplane in the world, crashed near Kharkhoff, 420 miles south-west of Moscow. Fourteen lives were lost. It is reported that M.K.A. Kalinin, the designer and director of the Kharkhoff aeroplane works, and Snegeriff, one of the best-known pilots in Russia, are among the dead. It seems that sabotage is suspected by the authorities, for the O.G.P.U. (Soviet secret police) is represented on the commission of experts investigating the disaster. Twenty trial flights had been successfully made before the crash.
 

     The design and construction of the K-7 took five years. She had a span of 208 ft., weighed about 20 tons and accommodated 120 passengers. She was considered a big stride forward in the approach to the “all-wing” aircraft, and most of the accommodation and equipment was in the wing. A few days before the accident the existence of the K-7 was revealed to the general public by “Pravda.” It was declared that the aircraft represented a “victory of the utmost political importance,” as she was constructed entirely of Soviet steel from the mills at Duiepropetrovsk. Hitherto Russia had [imported] materials for her aircraft.

—The Aircraft Engineer, Supplement to FLIGHT, 30 November 1933, at Page 1201.

The K-7 was designed by Konstantin Alekseevich Kalinin and built over a two-year period at the Kharkov State Aircraft Manufacturing Company factory at Kharkov, Ukraine. It was intended as either a heavy bomber in military service or as a civil transport. The K-7 was the largest airplane built up to that time.

К-7 в полете (“K-7 flight”) (Уголок неба)
К-7 в полете (“K-7 flight”) (Уголок неба)
Константин Алексеевич Калинин

The K-7 was an effort to perfect a “wing only” aircraft. The tail surfaces were supported by tail booms. It was operated by a crew of 11 and could carry up to 120 passengers in compartments inside the wings. The K-7 was 28.00 meters (91 feet, 10.4 inches) long with a wingspan of 53.00 meters (173 feet, 10.6 inches). The extremely large wing had an area of 254.00 meters².

As originally built the airplane was powered by six 2,896.1-cubic-inch-displacement (47.459 liter) liquid-cooled, supercharged, Mikulin AM-34 single overhead cam (SOHC) 60° V-12 engines mounted in nacelles on the leading edge of the wing. The engines were rated at 750 horsepower, each, and drove two-bladed propellers. When it was determined that power was insufficient, a seventh and then an eighth engine were added to the trailing edge in pusher configuration.

The K-7 had an empty weight of 21,000 kilograms and maximum weight of 40,000 kilograms. It’s cruise speed was 204 kilometers per hour (127 miles per hour) and the maximum speed was 234 kilometers per hour (145 miles per hour). The service ceiling was 5,500 meters (18,045 feet) and the range was 1,000 kilometers (621 miles).

In military configuration, the K-7 would be armed with 20 mm cannon and 7.62 mm machineguns. A bomb load of up to 16,000 kilograms (35,274 pounds) would be carried.

Cамолет К-7

The Kalinin K-7 made only 7 test flights before it crashed. 15 of the 20 persons aboard were killed. Kalinin was not among the dead, as had been report by Flight in the article above. One of the two tail booms failed. Some suggested that sabotage was involved. A government commission determined that the structure of the tailbooms was sufficiently strong, but that oscillations induced by aerodynamic flutter led to the failure.

During World War I, Konstantin Kalinin was awarded the Order of Sv.Stanislav. He had been given the Order of the Red Banner of Labor in 1935. However, during the Stalin purges, on 23 October 1938, he was executed as an enemy of the state.

Kalinen K-7
К-7 на аэродроме (“K-7 at the airport”), left front quarter view with engines running. (Уголок неба)

© 2018, Bryan R. Swopes