DVB-102 long-range, high-altitude bomber
The DVB-102 was a long-range, high-altitude bomber [DVB = dalnij vysotnyj bombardirovshhik]. Only two prototypes were built. In 1939, on the drawing boards of the Boeing company and the design bureau of the 4th special department of the NKVD, better known as TsKB-29, sketches appeared at first glance of different aircraft - the four-engine B-29 “Superfortress” (“Super Strength”) and the twin-engine long-range high-altitude DVB-102 bomber. However, when comparing the designs of both machines, there were a number of similar technical solutions applied almost simultaneously, which indicates the high qualifications of their creators, who boldly used advanced technologies. The DVB-102 long-range high-altitude bomber was a twin-engine all-metal high-wing aircraft with a number of novelty elements in layout and design, equipment and armament, and two airtight crew cabins.
It has long been known that flights over long distances are more profitable to make at attack angles close to maximum aerodynamic quality and at economic modes of engine operation, which leads to a decrease in speed. Flight with maximum speeds is carried out at angles of attack corresponding to the minimum frontal resistance and at maximum engine operating modes. Combining great speed and range in an airplane was very difficult. The reason for this was the lack of powerful high-altitude engines, effective means of mechanization of the wing and, consequently, a rather low specific load on the wing. But there was a certain "middle ground" that allowed flying at acceptable speeds over long distances. To do this, it was necessary to raise the plane as high as possible.
The new machine was created under the direct supervision of Vladimir Mikhailovich Myasishchev. The design of the aircraft was proposed by Myasischev in 1939. The aircraft was approved in terms of the experimental construction of the design bureau in early 1940, and in June its construction began. The DVB-102 project was developed by the Myasishchev team, simultaneously with the projects of the high-speed high-speed interceptor “100” Petlyakov (Pe-2), the front-line bomber “103” Tupolev (Tu-2) and the single-seat fighter “110” Tomashevich. The DVB-102 was the only aircraft with the DVB designation, and the 102 was with reference to the other dis-similar aircraft under development at that time.
The project has been approved. In one of the factories in 1940, they began to build a prototype aircraft. A team of engineers who had never met before, quickly worked as a well-functioning mechanism. Work on the creation of the bomber went at a "frantic" pace, since the fate of the designers hidden in prison depended on its results. It was necessary to solve a number of complex technical problems, the most important of which were pressurized ventilation cabs, a chassis with a nose wheel, gun installations with remote control, and a power plant.
By the summer of 1941, static tests were carried out and the construction of the first flight instance continued. The relocation of the enterprise in the summer of 1941 delayed the assembly of the machine. In August 1941, the former workshops of the Civil Air Fleet, where the aircraft was built, were evacuated. The aircraft, called DVB-102 (long-range high-altitude bomber), was only ready for flight tests in the spring of 1942.
In the winter of 1942, DVB-102 was brought to the airfield. Klimov’s M-120TK engines with a capacity of 1800 hp were installed on it, equipped with TK-3 turbocompressors. In February, pilot Zhdanov completed the first flight, and by September state tests were carried out. However, the M-120 engine failed, and its use was discontinued. In 1943, M-71 engines with a capacity of 2000 hp were delivered. There were a lot of misunderstandings with them; I had to make a number of refinements and changes to the turbochargers installed later. Along the way, the front pressure chamber was changed and new cabin superchargers were delivered. At the same time, the construction of an aircraft backup began.
In the fall of 1943, the aircraft was handed over to the plant, where part of the Myasishchev Design Bureau, who at that time was appointed chief designer to manage the production and modifications of the Pe-2, was engaged in the development and testing of the DVB-102. Design bureau designed the DVB-102DM variants with MB-102 engines, without pressurized cabs, modified ones with M-120, ASh-73 engines with TK-3. The aircraft with M-71 engines with TK-3 was tested mainly in high-altitude flights from March 1944 to July 1945.
The DVB-102 design should be emphasized. For the main material D16, stamping, forgings and castings made of aluminum and magnesium alloys, a few plastics, were widely used; welding was very small. The fuselage with a diameter of 1.6 m - half-monocoque with an unprecedentedly large bomb bay 7 m long,edged with a powerful frame that provides torsional rigidity from the loads on the tail. At the same time, the shutter doors were retracted inside. Technologically, the fuselage was divided into ten compartments across and along. There were two pressurized cabins in the fuselage - a bow for the pilot and navigator-shooter and a rear for two shooters. This was done for the first time in the world - two pressurized cabins in a combat aircraft. The glazing of the cabins was initially single, then double glazed to prevent fogging. There was also a DVB-102N project without pressurized cabins. The doors of the cabins, the control post, the center section nodes were made of light alloy cast.
The wing area of 78.3 m 2 with a relative thickness profile of 16 ... 10% with an elongation of 8.2, it was the first such thin wing used on Soviet aircraft. Center section - three-spar, consoles - two-spar. Sheathing - a carrier, with a thickness on the upper side of up to 3 mm, with reinforcing corrugation underneath on it on the lower side, reinforced by angle stringers. The ribs are sheet, their shelves are rolled squares. The casing was preferred over the flanges of the side members in the perception of effort, and the wing was assembled from the upper and lower parts with a joint along the neutral axis of the side members. Subsequently, this design in a more complete form was applied on the wing of the Il-28 medium bomber.
Chassis with a nose wheel on a fork, two main racks - retractable in nacelles. The scheme is one of the first in the USSR. Cleaning - with a hydraulic system. The control of the aircraft is tough, double. Four-blade screws. Tanks are caissons built into the wing consoles.
Armament: one ShVAK gun in the nose, one BK machine gun and one ShKAS, coaxial in the upper rear mount, in the lower with remote control - one BK. In state tests, one ShVAK, two BK and one ShKAS were tested; 20 mm guns could be replaced with 23 mm guns. During the tests, engines, armaments and equipment were changed, refinements were made. Normal bomb load - 2 tons , with an overload - 4 tons (practically - up to 3 tons ). The empty mass fluctuated around 10t, maximum fuel supply - 3800 kg, oil - 250 kg. Normal flight weight - 16038 kg, reloading weight - 17800 kg. The speed with the ASh-71 engine is 430 km / h near the ground and 529 km / h at an altitude of 8450 m. The test pilot Opadchim achieved a ceiling of 11,500 m, an estimated range of 3,600 km, an acceleration of 670 m, and an overload of 750 m.
Despite the fact that the M-71F engine, which developed a take-off power of 2250 hp, passed 50-hour bench tests, its poor performance was constantly manifested in flights. So, for example, on July 20, 1945, during a flight in order to determine the height limits of engines at the first and second speeds of rotation of the supercharger at an altitude of 4200 m, the left motor failed due to the destruction of the cranks of the crankshaft. In parallel with the refinement of the first prototype, work was carried out on the design and construction of an understudy originally designed for the MB-100 engine. On January 1, 1944, the volume of assembly work was 54%, however, replacing the front cockpit on the first aircraft, changing the design of the wing of the understudy from wooden to metal and then relocating to Moscow slowed down its construction.
The DVB-102 with M-71F engines, due to the failure of one of them and the lack of new ones in the industry, and his backup was mothballed along with other aircraft of Myasishchev Design Bureau. Having stood for a long time near the hangar of the factory No. 240 at the Frunze Central Aerodrome, these aircraft were decommissioned, having been scrapped. But the ideas embodied in the DVB-102 did not die. It is enough to note that the design feature of its wing, together with the OKB-482 design team, migrated to OKB-240, headed by S.V. Ilyushin. A wing with a technological connector along the chord line along the span was used on Il-22 and Il-28 aircraft.
In 1946, after the closure of OKB-482, the DVB-102 variant with ASh-73TK engines was considered. According to calculations, with a take-off mass of 16,500 kg, the maximum speed of the machine at an altitude of 9,000 m was to reach 610 km / h, and a range with a bomb load of 2,000 kg - 4,500 km. There were other options, including those with M-82TK and M-ZOB engines. But, despite the requirements of the Air Force, OKB-482 was not restored, and they quickly forgot about the plane.
As a result of almost four years of work on the DVB-102, they demonstrated a maximum speed of 570 km / h, a practical ceiling of 10,750 m and a range of 3,740 km. The ceiling was comparable to previous Heavy Bombers [Tyazhelyiy Bombardirovshhik], the range and payload was comparable, and the maximum speed was superior. But by this time, work was underway on four-engine Tupolev long-range “64” bombers with AM-34TK and AM-46TK and DVB-202/302 Myasishchev engines with ASh-72TK and ASh-46TK engines, the calculated parameters of which exceeded DVB-102 and more fully meet the requirements of the Air Force in the late 1940s. These Soviet designs were soon set aside in favor of the Tu-4 copy of the American B-29, the soulmate of the DVB-102.
|Wingspan||25.17-25.3 m||83 ft 0 in|
|Length||19.5-19.9 m||64 ft 0 in|
|Wing area||78.3-78.8 m2||848.20 sq ft|
|empty plane||9807 kg|
|normal take-off||15500 kg|
|Take-off weight||15500-18000 kg||34200 - 39600 lb|
|ENGINE||2 x Ash-71FTK|
|ENGINE POWER||2 x 1620kW||hp: 2 x 2200|
|Max. speed at ground||456 km/h|
|Max. speed at height||565-570 km/h||351 mph|
|Cruise speed||445-468 km/h||277 mph|
|Max. rate of climb||420 m / min|
|Ceiling||10750-11500 m||37750 ft|
|Range w/max.fuel||2230-3740 km||1390-2340 miles|
|Bomb load||1000-4000kg, or 2000-3000kg|
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