Il Boeing B-17

B-17 Serial number 43-39338, the ill-fated aircraft which crashed into Mont Blanc on November 1 1946, was a Boeing model 299, more commonly known by the US Army Air Force designation of B-17G. It was one of the 8,680 B-17G’s built between 1943 and 1945. Although designed as a bomber, at the conclusion of WW-2, a number of these versatile 4-engined airplanes were used by the US Army Air Force’s European Air Transport Service, mainly for troop transport, the role in which the aircraft piloted by Col. H.H. Upham was operating at the time of the crash.

The B-17 “Flying Fortress” was the best known American bomber of the Second World War. Flown by the US 8th and 15th Air Forces in the bombing offensive against Germany in 1942-45, its role was daylight, high-altitude precision bombing, in line with the doctrine favored by the United States Army Air Force hierarchy. Beginning in January 1943, such attacks on Germany were mostly carried out by the US 8th Air Force based in the United Kingdom, where there were over twenty-five Bomb Groups equipped with B-17s. Its thirteen machine guns made it the heaviest defensively armed bomber of the war, and daylight bombing raids in massive close formations were undertaken in the belief that they would be capable of defending themselves against German fighter attack without fighter cover. However, by mid-1943, the 8th Air Force was losing so many aircraft to German fighters during raids deep into Germany that they were forced to curtail their offensive. It was only following the introduction of the P-51 Mustang, whose performance and long-range fuel tanks enabled it to escort and protect the bombers all the way to their targets, that the American bombing offensive was able to make a decisive contribution to the destruction of Nazi Germany. Only 36 Medals of Honor were awarded during the Second World War - 18 were awarded to men serving in B-17 crews.

From a technical point of view, the B-17 is an all-metal mid-wing cantilever monoplane with an aspect ratio of 7.58/1, a dihedral of 4½° and a wing section which varies from NACA 0018 at the root to NACA 0010 at the tip. The leading edge is slightly swept back by 8°. Structurally, each wing consists of an inner section carrying two engine nacelles, an outer section and a detachable tip, mainly in aluminium alloy, with spars, ribs and a stressed-skin covering. The inner wing sections house the electrically-operated, split trailing edge flaps, while the ailerons are mounted on the outer sections. Both the ailerons and the flaps are fabric-covered, the ailerons being fitted with control and trim tabs. The semi-monocoque fuselage consists of bulkheads and circumferential stiffeners joined by longerons and longitudinal stiffeners covered by a riveted stressed aluminium skin. The cantilever monoplane-type tail unit is built from an aluminium frame whose fixed surfaces are metal-covered. The moveable surfaces of the elevator and rudder are fabric-covered and have both control and trim tabs. Electrical actuators extend and retract the main and the tail landing gears, while braking is on the main gear only and is hydraulically operated.

Power is supplied by four 1.200 HP Wright R-1820-97 9-cylinder radial air-cooled engines with GE type B-22 exhaust-driven turbo-superchargers. The propellers are Hamilton-Standard 3-bladed constant speed airscrews of 11 feet 7 inches (3,54 m) diameter. Fuel is carried in self-sealing wing tanks – 6 main tanks, 3 in each inner wing section, hold a total of 1,700 US gallons (6 435 liters) while a further 1,080 US gallons (4 088 liters) are carried in 18 feeder tanks (the so-called Tokyo tanks), 9 in each wing. Avionic equipment of the period included an autopilot, 2-way radio and a radio-homing device.

Overall dimensions:

  • Wingspan: 103 feet 9 inches (31,6 m)
  • Length: 74 feet 9 inches (22,8 m)
  • Height: 19 feet 1 inch (5,8 m)

Performance:

  • Max speed: 295 mph ( 472 kph) at 25,000 feet (7 625 m)
  • Service ceiling: 35,000 feet (10 670 m)
  • Normal range: 1,100 miles (1 760 km) at 220 mph

An extensive historical profile of this fascinating aircraft can be found here.

Hystoric article (Boeing courtesy)

 

 

 

 

 

 

 

 

 

Altri video sul B-17:

Amazing Story (S. Spielberg)

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