Boeing Model 450 (B-47 Stratojet)
Boeing Model 450 (B-47 Stratojet)
By the beginning of 1944. Four U.S. companies were involved in the design of the bomber / reconnaissance aircraft with turbine engines. The original proposal Boeing Company (Model 424) did not cause any interest. The second project (Model 432) was introduced in late 1944. and had the engine, hidden in the center of the fuselage, wing and direct, similar to an aircraft wing model 424. While working on the next stage, the company Boeing examined the data of the German aerodynamic research. Mr. Yermansky achievements in the application of the swept wing led to the borrowing company Boeing wing straight sweep for the next project proposal Model 448 with six engines inside the fuselage. However, such a layout of the power plant rejected the U.S. Air Force, who believed that such an arrangement of the engines will create problems for their maintenance and safety. As a result, in the fourth project proposal for Model 450, retained the swept wing, six engines were installed under the wing. Model of The Boeing Company has been built in this configuration, and official inspection in the spring of 1946. led to the conclusion of the contract for two prototype XB-47 (Model 450-3-3). They are somewhat different from the layout, changes in generally contain a larger wingspan and modified chassis. The first of two test aircraft flew on 17 December 1947. Plane XB-47 had a high aspect ratio wing with a laminar flow, defined by the scheme vysokoplan (the wing was so thin that it could not contain the fuel tank). This thin design also meant that the wing was very flexible, it caved in on the ends of 1,52 m (5 feet) up and down from the starting position. The design of the wing and led to the unusual structure of the chassis, for which the wing was not space. Instead, the concealment of two-wheeled landing gear (bicycle type), installed on the axis of long thin fuselage, and driving stability on the ground provide small console wheels, retractable inside the engine nacelles. In the early design stage it was clear that a full-size main chassis make it impossible to break the front wheels under normal takeoff, and as a result, the height of the two main landing gear was changed so that the aircraft was on takeoff in a position where he must stay in isolation from ground, when reached by speed. Each wing panel is also carried on three engines in gondolas, two twin close to the board and the third a short distance from the ends of the wing for advanced aircraft engines were installed GE (General Electric) J35-thrust 1701 kg (3750 lb). The fuselage provides accommodation of the crew of three: pilot, copilot / gunner, and a navigator / operator of the bombing, he also had a large bomb bay to accommodate large and heavy thermonuclear bombs of that era, but could be modified for delivery of 9979 kg (22000 lb) of conventional bombs ; allows you to set takeoff boosters JATO (jet-assisted take-off); and was equipped with a remotely controlled defensive armament in the tail. Score aircraft HB-47 was expressed in the contract for 10 vehicles variant B-47A (Model 450-10-9) from the U.S. Air Force, the planes were intended for large-scale flight testing and familiarization. In general, such prototype, aircraft B-47A differed presence of more powerful jet engines of J47-GE-11 Thrust 2,359 kg (5200 pounds) and is widely used for finding the best options of the tail of weapons and fire control system. The first of these machines up into the air on June 25 1950., The day when the war broke out in Korea. The first real production version (only built 399 copies) was the B-47B (Model 450-11-10). It differed from the B-47A strength modifications enabled the flight operations with an increased gross weight, in-flight refueling system and necessary equipment for podkrylnyh fuel tanks. Later serial planes, starting with 88 – second car models were equipped with J47-GE-23 Thrust 2,631 kg (5800 pounds). The first of these aircraft flew on 26 April 1951. And they began to operate the U.S. Air Force two months later. Machinery main production version B-47E (Model 450-157-35) (it was built more than 1600 aircraft in the bomber and reconnaissance versions of the aircraft) contained a large number of important changes, which included a strengthened landing gear for military operations with an increased gross weight, a modified nose section with the allocation volume for the system in-flight refueling, with an ejection system for the crew, drag chute to reduce the landing run. The tail armament was replaced by 20-mm cannon, an internal system boosters for take-off gave way to the drop outside the holder, capable of carrying up to 33 rockets thrust 454 kg (1000 pounds) each, the aircraft was fitted with new engines, J47-GE-25 with water injection and thrust of 3266 kg (7200 pounds). The first B-47E flew on 30 January 1953. and shortly thereafter went to the Strategic Air Command. At the top of your application, in 1957., 28 medium bomber wings of the U.S. Air Force Strategic Air Command were armed with 45 machine-47 each, plus 300 aircraft deployed to perform other functions, plus 300 who were in reserve. The total number of cars totaled more than 1800. Bomb attack at low altitude required the use of new technology for bombers bombing. It included a fast approaching the target at low altitude, steep slope (pitch up) to enter the half-loops (the bomb dropped before the aircraft takes a vertical position) and the final half-roll (rotation around the longitudinal axis through 180) at the upper loop. This final part of the maneuver was a classic bend “bunting” caring aircraft from the target at a long distance before the explosion of a bomb. Wing aircraft of B-47 was not designed for such maneuvers, or to increase the resource, which required him to strengthen and lead to cost huge sums of money to rework the construction of the wing and its hardening. Aircraft B-47, converted in such a way have been designated B-47E-II. Modified to a greater degree of B-47B aircraft for transfer to the standard B-47E, plus modifications to the design of the wing, were designated B-47B-II. The B-47 in 15 years was in the service in the combat formations of strategic aviation. He rightly takes pride of place in the history of military aviation, as the world’s first turbojet bomber with swept wing, which was built on a large scale. Considerable amount of production has led to the emergence of a large number of variants of the aircraft.
B-47B-II: the designation of aircraft B-47 after conversion to an improved standard. B-47B/CL-52: a B-47B aircraft was handed over to the Royal Canadian Air Force, used for testing was built in Canada Orenda Iroquois turbojet engine (Orenda Iroquois). DB-47B: changed version of the B-47B in the management of unmanned aircraft, which is intended primarily for the GV-47E, but also for other unmanned aircraft targets. RB-47B: mark 24 aircraft B-47B, refitted for aerial reconnaissance (some of designated YRB-47B), bearing eight cameras and other equipment in a special compartment bomb bay. TB-47B: mark 66 standard aircraft B-47B, modified for training pilots and navigators. YDB-47B: one plane B-47B, converted to carry, launch and management of missile Bell GAM-63 Rascal (Bell GAM-63 Rascal). XB-47D: two aircraft B-47B, converted to test turboprop engines Wright (Wright) YT49-W-1, one of these engines rated 7241 kW (9710 hp) are set in place a pair of J47, on each side. DB-47E: identification of two aircraft converted B-47E, and two generally similar YDB-47E, also used for commissioning and testing of missiles Bell GAM-63. QB-47E: 14 cars B-47E converted into radio-controlled unmanned aircraft target. RB-47E: key strategic fotorazvedyvatelny variant aircraft B-47, built 240 cars; bombing equipment was replaced with equipment for night photography. WB-47E: 24 aircraft B-47E, converted for use as spies weather. YB-47F: one aircraft B-47B, was used for tests of the probe cone-flight refueling. KB-47G: designation of one aircraft B-47B, equipped as a tanker for carrying out experiments on the in-flight refueling aircraft, together with YB-47F. RB-47H: mark 32 machine B-47, issued in series to achieve the objectives of electronic intelligence. ERB-47H: three aircraft B-47E, converted for the same role as the aircraft RB-47H, but with the deployment of 5 members of the crew. YB-47J: designation of a standard bomber, converted into a test stand for a new radar system (AI-2) for navigation and bombing. RB-47K: further 15 new aircraft RB-47E were released under the ticker symbol for the exploration of the weather. EB-47L: 35 cars B-47E, refurbished in 1963. to serve as relay stations.