B-17.com

The Boeing B-17 Flying Fortress, a four-engine heavy bomber aircraft was built in the 1930s for the United States Army Air Corps (USAAC). It was the chief bomber employed by the American Air Force in Europe throughout the bombing operations against the Nazi Germany. The B-17 also contributed on a lesser scope in the combat in the Pacific region where it carried out raids against Japanese war forces.

On 8th of August 1934, the U.S. Army Air Corps (USAAC) put forth a proposal for a multi-engine bomber to take over the Martin B-10. The conditions laid were that it should be able to bear a “useful bomb-load” at a height of 10,000 feet for 10 hours and have a minimum top speed of 200 miles per hour. At Wright Field in Dayton-Ohio, the contest for the Air Corps contract to construct 200 bombers was to be determined by a “fly-off” between the Douglas DB-1, Boeing’s design and the Martin Model 146.

Contending for the deal, the Boeing outperformed its opponent and met the Army Air Corps’ expectations.  Boeing lost the deal as the prototype crashed however the Air Corps was impressed with Boeing’s design, and so they placed an order for 13 B-17s for further assessment. From its inception in 1938, the B-17 Flying Fortress underwent various design revisions.

The prototype B-17 was designed at Boeing’s expense, by a group of engineers managed by E. Gifford Emery and Edward Curtis Wells. It shared features of the investigational Boeing XB-15 bomber and the Boeing 247 transport airplane. The B-17′s armor comprised of around 4,800 pounds of ammunitions on two racks behind the cockpit and five 0.30 inches machine guns. It was power-driven by four Pratt & Whitney R-1690 “Hornet” radial engines each of which produced 750 horsepower at 7,000 feet. Boeing had created the only war aircraft that could carry on with its mission if one out of its four engines failed.

On 20 August 1935, the revised prototype travelled between Seattle to Wright Field in nine hours and three minutes at the speed of 252 m/h i.e. loads quicker than the contract competition. The GHQ Air Force understood that the long range potential of four engine large aircraft was more competent than shorter ranged twin-engined airplanes and therefore, the B-17 was better suited for their needs and requirements. Enhanced with better flaps, controls and Plexiglas nose, the B-17Bs were delivered in batches of five between July 1939 and March 1940. In July 1940, and a substantial order for 512 B-17s was placed.

The air-crafts served in every World War II combat sector. The B-17 equipped 32 overseas combat groups. The B-17 was primarily employed by the United States Army Air Forces (USAAF) in the daytime precision planned bombing operation of World War II against German industrial and military base.

In 1941, B17’s were based in Britain to aid the Bomber Command. With a service upper limit superior to all its Allied contemporaries, the B-17 earned a solid reputation as an effectual weapons system, dropping a larger number of bombs than other U.S. based aircraft in World War II. Out of total 1.5 million metric tons of bombs dropped on Germany, 640,000 tons were dropped from B-17s. Overall, more than 12,000 B17’s were constructed during the war and almost 250,000 American soldiers flew in them. The role played by the B17 in the European war was of great significance.

Similarly, when the Japanese attacked Pearl Harbour in December 1941, the B17 was already based at Hickham Air Base. They were attacked while still on the ground which led to a loss of 12 bombers. Nevertheless, the attack on Pearl Harbour propelled America into its full military production capacity and Boeing was asked to build as many B17’s as was possible.  The B-17′s heavy gun shield was easily far more superior than the lightly protected Japanese planes.

Right from its pre-war initiation, the USAAC publicized the aircraft as a tactical weapon; it was a powerful, high flying, long range bomber that could protect itself and return home in spite of extensive war damage. B-17’s fame rapidly built on as a legend and the extensively spread war incidents, stories and photos of B-17s, and its survival of enemy attacks only served to amplify its iconic position.

Several models of the basic idea of the B-17 were developed between 1935 and 1942, as improvements were needed.  The most notable feature of this design is that the overall design of the B-17 remained the same over each new development.  The initial design was meant to be one that could be changed slightly, but produced in large quantities, therefore, an easy template to follow.

The Model 299

The first B-17 was the model 299.  Only one of these planes was produced, and it was the plane used in the ill fated test flight of July 28, 1935.  The test pilot crashed the plane because he failed to unlock the elevators.  What this means is that the plane was fitted with a special device that would lock the elevators in position in strong winds while the plane was on the ground.  These locks were intended to be released in a pre flight check.

The Model Y1B-17

The Boeing Aircraft Co. was dropped from the bomber production competition after the test flight of the Model 299, but once it had been determined that the crash was due to pilot error, the Army Air Corps ordered 13 test aircraft in 1936.  The main design difference was that the Pratt & Whitney engines were replaced with 850 hp Wright 1820s and the undercarriage was modified.  Of the 13 planes ordered, the 13^th was the only unit to undergo exhaustive flight testing.  The Y1B-17 was put to the test during a demonstration flight where they were to intercept the Rex, an Italian liner, while it was 610 miles away from United States soil, at sea.  Testing continued for three years, after which time (October, 1940), they were officially transferred to the 19 Bombardment Group at March Field.

Boeing Y1B-17A

This model was developed from the Boeing Model 299F, which was only intended to be a static test bed, not an aircraft capable of flight.  It was eventually converted to be capable of flight, in order to test supercharged engines.  Only one prototype was ever developed, and it underwent various engine tests, ending up with a bottom mounted turbo supercharger, the eventual standard on the B-17B.  The turbo supercharger engines allowed this aircraft to fly much faster and higher than the YB-17.  After adequate testing and experimentation with engines, this model became the B-17A.

Boeing B-17B

This plane was a much improved version of the B-17A.  The more notable changes included a redesigned nose, a much larger rudder and a bigger set of flaps.  In redesigning the nose, the metal had been replaced with plexiglass, allowing the gunner a better view and making it shorter than the 17A by a full seven inches.  39 of these planes were ordered by the USAAC between 1938 and 1939.

Boeing B-17C

The noted improvements to the Model B-17C were a change from a 1,000 hp engine to the 1,200 hp Wright R-1820-65 radial.  The waist gun blisters formerly located on the sides of the plane were replaced with sliding panels that could be closed or opened, affording better safety for the crew of the plane.  A bathtub turret replaced the ventral gun blister.

Boeing B-17D

Some improvements over the B-17C included cowl flaps, a much better electrical system, armor plating and self sealing fuel tanks.  One of the more notable B-17Ds is “The Swoose” currently on display at the National Museum of the US Air Force.

Boeing B-17E

This modified and improved model had a completely redesigned tail with a vertical stabilizer and fairing.  The tail gunner area was added because of the vulnerability of the earlier models to an attack from the rear.   The waist gunner windows were enlarged from the basic teardrop shape to a larger rectangle design, allowing for better sighting.  The bathtub turret was also replaced with a Bendix remote controlled belly turret.  Eventually, the Bendix turret was replaced by a Sperry ball turret after 112 planes had been produced.  A further Bendix turret was added just behind the cockpit on the top fuselage.  In total, 512 of the B-17E were produced between 1941 and 1942.  Most of the improvements were aimed at keeping the crews of these planes safe and alive during combat.

Boeing B-17F

The B-17F could carry just about double the bomb load of any previous versions of the B-17 at 8,000 pounds.  The result was that the cruise speed dropped by about 70 miles per hour due to the large weight increase.  3,400 of the B-17F were produced by the combined efforts of three manufacturers – Boeing, Lockheed-Vega and Douglas.  The most famous of this production run was the Memphis Belle.

Boeing B-17G

More than 8,500 of this model were produced and it was considered the final result of continual improvement of its predecessor models.  The Bendix chin turret was introduced in this model.  After their use in World War II, many of these planes were converted for other uses, including VIP transport, special duty training, drones, engine test beds, early warning aircraft and air-sea rescue units.

A brief History of the B-17 Bomber

After the devastating carnage of World War One, The American Army Air Corps decided that a new bomber was justified and felt the need for a 250 mph bomber with an effective range of 2,000 miles along with an operating ceiling of 10,000 feet. At the time, an ailing enterprise, Boeing Co. rose to the challenge and Project Model 2-99 was born.

In July 1935, the Boeing Model 2-99 was rolled out., weighing in at 15 tons and equipped with four engines. One journalist watching its first flight in Seattle made the comment that the Boeing 2-99 looked like a flying fortress in the air due to its extreme number of machine guns. The name stands to this day.

The Boeing 2-99 had specifications that exceeded the U.S. Army Air Corps but sadly crashed in October 1935 during an evaluation exercise, killing both its two man crew. The bomber was subsequently disqualified but a small number was ordered for further evaluation purposes.

With the situation in Europe becoming increasingly intense, the Boeing 2-99, now renamed the B -17, with super charged engines and a flying ceiling of 30,000 feet , was pressed into action. 20 were sent to Britain as part of the Lend-Lease Deal but had an inauspiscious debut.

When Pearl harbor was attacked by the Japanese in December 1941, 12 B-17′s were lost on the ground. That event however was the start of the successful career of the B-17 Superfortress and the Boeing Co. was asked to produce as many as possible, with 8,680 coming off of the assembly line between July 1943 and April 1945.

A weapon of choice for the U.S. 8th Air Force, based in Britain, the B-17 was primarily deployed in daylight precision strategic bombing campaigns against Germany, with industrial and military complexes as the main targets.

The first full B-17 mission against german targets took place in August 1942, but german fighter pilots quickly realized that a frontal attack all but neutralized the enormous firepower that was primarily positioned on the sides of the bombers.

In August 1943, 211 B-17′s participated in the raid on the Schweinfurt ball bearing factory, an all important target since it had the capacity to produce 52% of german ball bearing needs. It was also defended on a massive scale and 60 B-17′s were lost in action, an almost 30% rate. It was subsequently estimated that one thirf of B-17 crews would be lost.

However, a study conducted by the U.S. 8th Air Force led to a change of flying pattern and with the emergence of the new Model G, with more machine guns at the front of the B-17 to fight off frontal attacks, the B-17 retained its title as the backbone of the U.S. Air force during World War Two.

Overall description of the B-17 Superfortress Bomber :

* Length : 74 feet, 9 inches

* Height : 19 feet 1 inch with gear down

* Wing span : 103 feet 9 inches

* Weight : 41,000 lbs tactical empty and 64,500lbs maximum grss

* 4 1,200 hp engines

* Four .50 in machine guns and one .30 nose machine gun in the B-17C model increased to thirteen .50 in machine guns in the G model

* 8,000 lbs bombs for short range missions and 4,500 lbs bombs for long range

*  287 mph maximum speed and 182 mph in cruising mode

* 2,000 miles range

* Crew of 10

It should be noted that the B-17 was famous for absorbing extensive damage, reach its target and still bring its crew home.

The Boeing B-17 Flying Fortress is famous for the World War II military aviation stories that have become legendary. The origins of this heavy bomber are from the requirements of the United States Army Air Corps’ need for a high altitude daylight bomber necessary to attack strategic enemy targets and be able to take enormous sustained damage. The US goal was to establish air power over Europe to be a major force in warfare in spearheading an American offensive in Europe which remained intact through the Second World War. In the mid-1930s, the Boeing Flying Fortress bomber achieved this aim.

In the summer of 1934, Boeing first began conception of this new military heavy bomber. On September 26, 1934, Boeing received $275,000 in initial funding to design, develop and build the prototype that would become the Flying Fortress. The Project Engineer, E. Gifford Emery, with the help of his assistant, Edward C. Wells, were the primary contributors for the existing design and specifications of the aircraft.  Then called Model 299, the bomber had a wingspan of 103 ft 9 in (31.6 m) utilizing four Pratt & Whitney Hornet radial engines rated at 750 hp per engine.

On July 17, 1935, the Model 299 was first unveiled for the public to see and was touted as the world’s first entirely metal four-engined heavy bomber. However, the press at the event were more impressed with the sheer size and streamlined features. Richard Williams, a reporter from the Seattle Daily Times assigned to cover Boeing’s event, was so moved by seeing the aircraft that that he wrote that the aircraft was a “flying fortress”. Boeing’s public relations department jump on the attention the plane received in being called Flying Fortress and was later adopted as a company registered name.

Only eleven days after that first public appearance of the Model 299 aircraft, the first test flights were made with pilot Leslie Tower taking command in flying the heavy bomber. The test flights were a great success and only experience the problem of having some tailwheel oscillation when taxing down the runway. Then on August 20, 1935, the bomber was flown from Seattle, Washington, to Dayton, Ohio, under the evaluation of the Air Corps. This flight was made in 9 hours and 3 minutes, with an average speed of 233 mph (375 km/hr), leaving all of the examining officers at Wright Field very impressed.