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Boeing Model 299 / YB-17

The 299 was the prototype of the B-17 Flying Fortress, probably the most significant air weapon of its time.

In 1930, C.L. Egtvedt, of Boeing, who had been present when the Ostfriesland was sunk, delivered a Boeing fighter to the Navy. A Navy officer remarked to him that, despite all the progress aviation had made, there still was no aerial counter part for the battleship --- an airplane that could operate far from its base, deliver a heavy blow to the enemy and protect itself from attack.

In 1934, the Army first announced its competition for "multi-engine" bomber. The specifications called for a “multi-engine” bomber that would have a high speed of 200-250 mph at 10,000 feet, an operating speed of 170-200 mph at the same altitude, a range of 6 to 10 hours, and a service ceiling of 20,000-25,000 feet.

Boeing engineers went to work to give shape to the design that Egtvedt had formed as a result of these discussions. The project was financed entirely with company funds [the common practice at the time]. The Model 299 was the latest in a long line of Boeing achievements dating from 1916. Among these in recent years had been the company's high-speed twin-engined bomber of 1931 and commercial transport plane of 1933, both of which established the current trend in aircraft design and construction.

Boeing designers figured that with a conventional 2-engine type of airplane they could meet all specifications and probably better them. But such a design probably would not provide much edge over the entries of competitors. They decided to build a revolutionary type of 4-engine bomber.

The requirements were for a multi-engined bomber capable of carrying a ton of bombs at more than 200 mph over a distance of 2,000 miles. Among other things, these requirements called for a high speed of from 200 to 250 miles an hour at 10,000 feet altitude, for an endurance at operating speed from six to ten hours, and for a service ceiling of from 20,000 to 25,000 feet. Boeing officials said, however, that the Model 299 would meet or exceed specifications of the Air Corps as set forth in a public call for bids and equipment.

In July 1935 an airplane such as the world had never seen before rolled out on the apron of the Boeing plant at Seattle, Wash. It was huge: 105 feet in wing span, 70 feet from nose to tail and 15 feet in height. It was equipped with 4 Pratt & Whitney Hornet 750 Hp engines and 4 Hamilton Standard 3-bladed constant-speed propellers. To eliminate air resistance, its bomb load was tucked away in internal bomb bays. Pilots and crew had soundproofed, heated, comfortable quarters where they were protected from the rigors of high altitude flight. And the big bomber bristled with formidable firepower.

Boeing's Model 299 was based heavily on the company's experience with the all-metal Model 247 commercial airliner. It was basically a marriage between the aerodynamic and structural features used by the Model 247 and the basic four-engined format used by the B-15, Boeing's Model 294 XBLR-1 bomber. The aircraft was to be powered by four 750 hp Pratt & Whitney R-1690-E Hornet nine-cylinder air-cooled radials, each driving a three-bladed propeller. The large, thick-section wing was to be mounted low on the cylindrical-section fuselage. The main landing gear was to retract forward into the inner engine nacelles, with the lower edge of the wheel protruding into the airstream.

Model 299 carried a crew of eight, a pilot, copilot, bombardier, navigator/radio operator and four gunners. There were four blister-type flexible machine gun stations, each of which could accommodate a 0.3-inch or 0.5-inch machine gun. One was in a dorsal position in the fuselage just above the wing trailing edge, a second was in a ventral fuselage position just behind the wing trailing edge, and a blister was mounted on each side of the rear fuselage in a waist position. There was an additional station for a machine gun in the nose. All of the guns were manually swung. Up to eight 600-pound bombs could be carried internally. Loaded weight was 43,000 pounds.

In order to prevent damage by wind to the tail surfaces while the plane was on the ground, the elevators were locked in position. Before takeoff, the pilot would unlock the tail surfaces by releasing a spring lock in the cockpit.

Hailed as the fastest and longest range bomber ever built, the giant four-engined all-metal airplane was brought to light on 05 July 1935 by the Boeing Aircraft Company of Seattle after more than a year of work on the project. Known as the Boeing 299, the huge craft would undergo test flights before being submitted to the United States Air Corps in open competition with other types at Dayton, Ohio. These tests, it was announced, were expected definitely to stamp the plane as the most formidable aerial defense weapon ever offered this country, with far more speed and a substantially greater cruising range than any bomber ever before produced.

The Boeing "aerial battle cruiser" had a wing span of approximately 100 feet, length of nearly 70 feet, height of 15 feet, and gross weight of about fifteen tons. It was of the all-metal mid-wing type, equipped with four Hornet engines of over 700 horsepower each and with the new Hamilton Standard three-bladed constant speed propellers. Clean streamlining is a feature, with retractable landing gear and tail wheel as further aids to speed. Officials declared the plane to be the first military type which will be able to complete a mission in the event one engine ceases to function.

A number of new armament installations, developed by Boeing engineers, are carried in addition to the latest types of flight and engine instruments, including an automatic pilot, two-way radio telephone equipment and a radio "homing" device. Air brakes are used for the first time in any American aircraft, with these as well as the craft's wheels and tires having been especially developed. Construction is of typical Boeing semi-monocoque type, the structure consisting of longerons, skin stiffeners, bulkheads and smooth outside metal skin.

First flight of the Model 299 took place on July 28, 1935 at Seattle with Boeing test pilot Leslie R. Tower at the controls. According to legend, a reporter having seen the 299 for the first time remarked, "Why, it's a flying fortress!" The name stuck. After a short period of factory testing, Tower and a three-person crew flew Model 299 to Wright Field on Aug. 20 for Air Corps evaluation. During this flight, it flew the 2,100 miles nonstop at an average speed of 232 mph at an average altitude of 12,000 feet, breaking all records for the distance. The prototype was submitted to the Army as Model X-299, but the Army wanted the designation changed, so it was officially changed to B-299.

The competitors of the B-299 were the Martin 146 and the Douglas DB-1, which were both twin-engine designs.

The B-299 prototype airplane was destroyed on Oct. 30, 1935 when an Army pilot took off with the controls locked. The findings of the Board of Officers convened at Wright Field, Dayton, Ohio, to investigate the cause of the crash on October 30, 1935, of the Boeing Aircraft Company Bombardment plane, model 299, were to the effect that the accident was not due to structural failure, or to the malfunctioning or failure of any of the four engines, the airplane control surfaces or the automatic pilot, but to the locked condition of the rudder and elevator surface controls (primarily the latter), which made it impossible for the pilot to control the airplane.

The Army was sufficiently impressed in the potential of this new bomber to place a service order for 13. It was then that the bomber received its designation, B-17. The Army decided to purchase 65 service test examples of Model 299 under the designation YB-17.

General Characteristics: Primary function: bomber Builder: Boeing Span: 103 feet 9 3/8 inches Length: 68 feet 9 inches Height: 14 feet 11 15/16 inches Weight: 32,432 pounds, gross Speed - top: 236 mph Speed - cruising: 140 mph Range: 3010 miles, maximum Service ceiling: 24,620 feet Power: Four Pratt & Whitney R-1690 radials of 750 hp. each Armament: Five .30, or five .50 caliber machine guns and eight 600 pound bombs

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Page last modified: 10-08-2018 02:01:08 ZULU