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Douglas XBLR-2 B-19 Hemisphere Defender

The Douglas B-19 heavy bomber was an example of the fact that the plane seemed like it was a good idea at the time, but the long debugging process in an era of rapidly developing technologies led to the fact that when the aircraft took to the air, it turned out to be obsolete. But still it was an elegant and very impressive aircraft. The Douglas XB-19, with a span of 212 feet, a weight of 84,431 pounds, and a range of 5,200 miles, was the Army's largest prewar bomber.

The B-19 was an excellent example of a project with completely new technologies of those years: an all-metal construction with a working skin. Such aircraft were not created using earlier technologies of internal braces and linen plating. If this were the case, the weight of the payload would tend to zero, and its maximum speed would be just over 100 mph (160 km/h) instead of just over 200 mph (320 km/h).

An exact parallel to such an aircraft could be the Soviet Tupolev ANT-26, intended for commissioning as the TB-6 super-heavy bomber . Being even larger than the B-19 with 12 engines and a wing span of 311 ft (95 m), it was suddenly canceled in 1936, and the financing was switched to small tactical bombers such as SB-2.

The War Department had given its approval to an experimental interest in the long-range bomber as early as 1934. It had supported the action leading to the development of the B-17, and though the decision to limit the initial procurement to thirteen planes had proved disappointing to the Air Corps, that decision nevertheless had maintained the project on a hopeful experimental basis.

Further encouragement came from War Department approval of a contract of 31 October 1935 with the Douglas Aircraft Company for the design of an experimental bomber even larger than the B-15. The contract carried an option for subsequent purchase of a prototype, and under an authorization of 29 September 1936 that option was exercised through a contract for the building of one experimental model.

Douglas set his sights higher, and in January 1936 a special group led by Sky (Schuyler) Kleinhans completed the first blueprints of the world's largest aircraft. Douglas XBLR-2 was supposed to have "six engines of at least 2000 hp each". Prototypes of such engines have already been built by Wright Aeronautical. The R-3350, also known as the Duplex Cyclone, was a very large 18-cylinder radial engine that seemed ideal for this task. However, at the end of 1937 the Army and the Douglas agreed to make the plane a little smalelr, and use only four such engines. The designation was changed to XB-19.

For the construction of the B-19 by Douglas, a giant hangar in Santa Monica was built. The huge wing, which set a new world record with a scale of 212 ft (64.618 m), was built as a single whole. It was a constructively and aerodynamically beautiful aircraft - rather like a giant DC-3 with a wing with even greater relative elongation. The length (almost exactly 50 feet (15.24 m)) of each slotted flap or aileron was so large that these surfaces were divided into inner and outer halves to avoid deflection using a hinged mount. In fact, the wing area of 4492 ft (417.3 m) was significantly smaller than those of the earlier giants Ca-90, Do-X and ANT-20, each representing old forms of construction and construction in which there was very it is difficult to achieve.

The bomber's fuselage was quite large and broad-browed in front and with a conical very thin tail that hardly looked strong enough to carry the colossal loads of the tail unit, which then had, among other things, the largest rudder of the lines built up to that time. The usual crew consisted of ten people. The cockpit with the two pilots side by side by modern standards looked almost empty, although it had a large center console with truly huge levers of traction control. Much more scales of instruments were in the compartment of the flight engineer, located further and the passageways from which led to the wing engines. Up to eight crew members, if necessary, could act as shooters, completing calculations for 37-mm guns, created by the American Armaments Corporation - located in the nose and front upper tower, for 0.5 dm (12.7 mm) Browning machine gun in the rear top tower and for manually operated two 0.5-dm (12.7 mm) machine guns under the steering wheel direction, two 0.5 dm and two paired 0.3 dm (7.62 mm) machine guns in the four traverse windows.

In the cockpit, which was light and airy with a large area of windows, there was plenty of room. The size of the bomb compartment, with a large margin superior to the largest one built before that time, could accommodate any of the 14 basic sets of bombs, as well as excessive load (for a range of about 2,000 miles (3,218 kg)) with a total weight of 37,100 lbs (16828.56 kg) . In addition, with a maximum refueling fuel, he could carry 1,500 pounds (680.4 kg) of bombs at a range of 7,000 miles (11,263 km).

Obviously, the key to such a long distance was the fuel supply, and in this, as in many other cases, the big Douglas set a new record: 9160 gallons (41642.203 liters), which is about 50 times the total fuel reserve of equivalent Royal bombers Air Force of the 1930s. Such a large stock of fuel, placed in the wing in the light-alloy sections, made the maximum weight of the giant 164,000 lbs (74,390.4 kg) almost twice the empty weight of 82,253 lb (37309,961 kg). Even with the take-off power of four large engines, this resulted in a load per unit of power of 20.5 lb / hp. (9,299 kg / hp), which was on the verge of admissibility with respect to the covered biplane, rather than for high-loaded monoplanes. As a result, it was already clear in advance.

The engines of the R-3350-5 Cyclone 18 were placed in rounded hoods and stopped on a huge wing. The hoods were tightly fitted around the engines. The power frame was usually non-removable, access to the engine was either in front or after unscrewing any of the nine bonnet panels, each of which gave access to the two cylinder heads. Cooling air went out along the leading edge through controllable flaps, expanding around the perimeter of the bonnet. The oil was cooled in tubular radiators in ventilation ducts under the leading edge located on the inside for internal engines and on the outside for external ones. A unique feature, which was subsequently abandoned, was the installation of each engine with nine pairs of dynamically-centered damping fasteners, attached to the cylinder heads around the front ring of the monobloc gondola. Various three-bladed propellers Hamilton Standard and Curtiss were installed with diameters from 15 ft 2 in (4.6 meters) to more than 16 ft 6 in (5 meters).

The B-19 was developed at the time when the so-called tricyle chassis became fashionable. As a result, the chassis was made exceptionally well. All three parts of the chassis had one wheel on each rack, although the main wheels were huge. All the units of the chassis were completely retracted with the help of a hydraulic drive, the nose post was retracted into a long niche between two doors, the main racks were retracted into the wing with the wheels forming the lower surface of the wing, as was the case with the Boeing 737.

During development it became increasingly obvious that the car would never be serial, in part because there were no engines of the required capacity in the future, and in part because huge and vulnerable bombers were not the best way to spend money on defense. Thus, the project had a low priority, combined with a fantastic and completely unanticipated demand for smaller aircraft - dozens were ordered, and hundreds and even thousands were ordered for such unexpected customers as Great Britain and France - there was simply no way to fulfill the initial schedule with the first flight in August 1939.

By 1940, the Army had declassified the giant B-19 bomber as many of its technologies were no longer cutting edge enough to justify keeping it secret. The press ran with the story and a large buzz was created about the Army's secret super-bomber that could fly across oceans and attack foreign countries while still having enough gas to make it home. Although the aircraft was massive, and had impressive features, it was being surpassed by smaller bombers that could be built in greater numbers.

Completed in the spring of 1941 and test-flown for the first time on 27 June 1941, controllability was generally quite acceptable and surprising considering the huge size of the control planes and the complete absence of any amplifiers. In the maiden flight, seven crewmembers were on board with Major Stanley M. Ulmstead in charge. The flight lasted 55 minutes from Clover Field in Santa Monica to March Field. The flight went by smoothly without any problems and was successful. Shortly afterwards, Donald Douglas would receive a congratulatory telegram from President Roosevelt. The USAAC unofficially accepted the XB-19 in October of 1941.

The XB-19 was finally accepted officially by the USAAF in June of 1942 after minor modifications were made to the planes brake system. The contract cost to the United States government was $1,400,064. The Douglas Aircraft Company also spent $4,000,000 in personal company funds. The XB-19 was extensively tested by the USAAF for eighteen months to see the engine performances and different altitudes and the maneuverability of the aircraft. The results of these tests would later go on to influence the design of the Boeing B-29 Superfortress and the Convair B-36. The XB-19 performed well in all aspects and was generally free of problems. The only problem noted however was the inefficient engine cooling process. Due to this, the cooling gills on the plane had to be open the whole time in longer flights, thus reducing the effective speed of the XB-19.

Tests proved that there were no fundamental flaws of design or structure, but, as in the case of the B-15, the size and weight of the plane were too great for the power plants. Consequently, the later B-29, though it mounted engines more powerful than those of the XB-19, was designed as a smaller plane. Only one experimental model of the B-19 was built, but that paid more than ample dividends in the lessons applied to future bomber development within the AAF.

In early 1943, it was decided to allocate a significant amount for a general alteration from nose to tail, to make it a much better cargo ship. All gun systems were removed, the fuselage was gutted and rebuilt only for cargo, and many systems, including radio, were upgraded. The original engines and gondolas were removed and replaced with engines that did not appear seven years ago: Allison V-3420. The V-3420-11 was designed for 2,600 hp. and consisted of two V-shaped 12-cylinder power packs that propelled the four-bladed propeller of Curtiss Electric with a diameter of 19 ft (5.791 m).

The new U.S. Air Force had plans to save the B-19 for eventual display, but in 1949 the Air Force did not have a program to save historic aircraft and the Air Force Museum had not yet been built. The B-19 was therefore scrapped, but two of its enormous main tires were saved. One was put on display at the Hill Aerospace Museum at Hill Air Force Base in Ogden, Utah and the other has been on display at the National Museum of the United States Air Force in Dayton, Ohio, in the "Early Years" gallery for many years.

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Page last modified: 01-08-2018 06:37:35 ZULU