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The design bureau began to deal with the problems of increasing the range of the Tu-2 and the creation of a long-range bomber on the basis of a front-line vehicle as early as 1941, at the stage of designing and fine-tuning the prototypes "103" and "103U". Then they prepared a draft design of the first modification of the 103D aircraft, which differed from the 103U in the increased wingspan from 18.8 to 21 m and the fuel reserve.
In the initial period of the Second World War, when all the forces of the aviation industry were focused on the deployment of mass production of front-class aircraft, work on the 103D aircraft did not go beyond the draft design, and even with the subsequent fate of the base aircraft, not everything was clear. The situation changed in 1943, when the Air Force urgently needed a modern long-range bomber.
Work on Tu-2D proceeded on the basis of attempts to modify the serial Tu-2 for several years. Several types of machines were built and tested that fell under the appropriate classification, but none of them was brought to condition and passed into series: in the second half of the 40s, combat aviation was actively switching to jet thrust.
When designing a standard front-line bomber Tu-2S in 1943, it was envisaged to be quickly converted into a long-range version - the Tu-2D aircraft. According to the materials prepared for the development of the Tu-2S, the main parameters of the Tu-2D aircraft were close to the D project. In development of these design works and striving to give the Air Force the long-range bomber it needs under TTT, prepared by the Air Force for Tu-2D, the OKB converted two serial Tu-2 (No. 714 and 718) into Tu-2D. According to the OKB, these machines were designated "62" and differed in the number and placement of the crew, the size and design of the fuselage nose.
The first was ready in June 1944, "62nd", converted from Tu-2 No. 718 to the Tu-2D type, code "62". After successful factory tests, the first Tu-2D in November 1944 was transferred to the Air Force Research Institute for state tests, which were carried out from November 1944 to April 1945, at the very end of the war with Germany. Based on the tests, the Air Force Research Institute made a conclusion about the possibility of creating, by modifying the serial Tu-2, a long-range bomber that satisfies the TTT of the Air Force to Tu-2D. The machine itself was not recommended for service, as it had a large number of design defects.
In parallel with the work on the first version of "62nd" was the creation of its second, improved sample. The aircraft was converted from the serial Tu-2 No. 714.
The crew was increased to five people: - pilot, ship commander, - second pilot - gunner, located behind a ledge in relation to the first, with redundant control; if necessary, he could, turning, strengthen the defense with the fire of his blister installation, navigator-bombardier; his workplace was in the very nose of the fuselage, the gunner-radio operator, in the rear cockpit, the gunner of the hatch installation, in the rear cockpit.
New fuselage nose extended by 600 mm. The nose section of the fuselage with the pilot's and navigator's stations was the most important innovation. The commission was presented with the layout of the nose of the Tu-2D aircraft with the cockpits of the pilots and the navigator and the blister mount of the Berezin machine gun for the second pilot, similar to the rifle mount of the navigator on the Tu-2S aircraft, which was approved. The areas of the wing and tail consoles have been increased. Installed bomb racks with a capacity of 4000 kg. The capacity of the fuel tanks has been increased to 3860 liters.
The aircraft equipment provided long-range piloting under any weather conditions, at any time of the day. For this purpose: the RPK-2 radio compass was installed instead of the RPK-10, the possibility of conducting astronomical orientation was provided, the AK-1 automatic course was installed with fly-by-wire control from the navigator and the first pilot, the oxygen supply was increased to 12 liters for each crew member.
From October 1944 to March 1945, the second Tu-2D was tested under the factory test program. Then the car, like the first Tu-2D, was transferred to state tests, which it passed from July to October 1945. The second aircraft had a fuselage length of 14.42 m, a maximum take-off weight of 13,370 kg, and a bomb load of 4,000 kg. But this attempt by the OKB did not find an approving response from the military.
Unfortunately, during the tests, defects were found that were not previously noted. The Air Force Research Institute commission not only drew attention to them, but also expressed its opinion on the way to eliminate them.
But the main problem was that, although the characteristics of the aircraft were close to the specified ones, it lacked mainly - the range. Its high-speed range, that is, the range at increased speed, turned out to be almost 400 km, and the maximum one was 200 km less than the specified one. To comply with TTT, it was necessary to increase the fuel supply, to strengthen individual structural elements, for example, the chassis. All this required serious improvements.
In the conclusion, according to the results of state tests, it was noted that the aircraft "62" No. 714, according to flight technical data, is better than the bombers in service with the Air Force Il-4, Er-2 and others. However, a large number of defects, as presented, does not allow recommending it for production. After elimination, it must be presented for retesting. On November 13, 1945, aircraft # 714 was returned to plant # 156.
We didn’t start to adjust the car, we relied on new, more advanced modifications. After some time, the 62nd was converted into an experienced torpedo bomber 62T, and then into a long-range 69.
Armament. Three defensive 12.7-mm UBT machine guns (195 rounds per machine gun) and two 20-mm ShVAK cannons in the roots of the wings (150 rounds per cannon).
Bomb load - 1000 kg, maximum - 4000 kg.
Considerations about the production of the aircraft "65" were prepared simultaneously with the note on the aircraft "67" - on October 30, 1944, the "65th" machine was created by modernizing the production aircraft Tu-2 No. 201, built by the plant No. 166. At the same time it was planned to replace the ASh-82 motors with the AM-39 liquid-cooled motors with TK-300B turbochargers. Since the AM-39 engines were not completed, they decided to supply liquid-cooled AM-44 engines (with a capacity of 1650/1950 hp) with AM-TK-1B (TK-300B) turbochargers, AV-5LV-188B screws with a diameter of 3, 8 m mechanically controlled, separate fuel system, new oil system and engine starting system.
The engine frames and hoods, the fuel system with separate feed valves, the oil system and the launch system were redesigned, the radio operator's lantern was redesigned for the wind turbine-1, a hatch for a rescue boat was made, a controllable stabilizer was installed, the forward extension of the main landing gear wheels by 125 mm, - magnetic compass PDK-44 is installed.
Armament was supposed to consist of two ShVAK cannons with 150 rounds of ammunition, VEU-1 installations (B-20 cannon, 200 rounds of ammunition), VUS-1 (Berezin machine gun, 190 rounds of ammunition) and LU-68 (Berezin machine gun, 350 rounds of ammunition).
The aircraft was built in May 1946. From May 21, 1946 to May 6, 1947, factory tests took place. The first flight took place on July 1, 1946.
Although the work lasted almost 12 months, it was not possible to capture the flight characteristics of the aircraft "65". Motors and pumps were out of order, oil was thrown out, flames from the TC, motors were shaking ... The crew was not able to make a single full-fledged flight. By order of the ministry, testing of the aircraft and work on it was stopped.
Thus, the aircraft "67" and "65" differed mainly only in power plants. Their fate was predetermined by the backwardness of the country's engine-building industry.
Working on increasing the flight range of the 62nd (Tu-2D), the designers in 1945 prepared for testing its version 67 with ACh-30BF diesel engines (1900 hp). The plane was built in November 1945.
Structurally, the "67" project was a modification of the five-seat version of the "62nd" car. Due to the increase in the range and duration of the flight (at high altitudes) "67th" was equipped with oxygen equipment KP-14 and with an AP-42 autopilot. The middle point was converted into . In addition to bomber weapons, it was supposed to install a mine and torpedo.
The following measures were taken to modify the production vehicle into a proposed new long-range bomber variant:
Airplane "67" is an airplane "62" with replacement of ASh-82 engines for diesel engines ACh-30 BF. Engine frames and hoods are made according to new drawings. Water cooling systems - similar to the aircraft "63". An additional gas tank is made for the aircraft in the bomb bay with a power supply system with a crane. The aircraft is equipped with AV-7L-22 weather vane screws with R-10 regulators.
Aircraft equipment. All hydraulic equipment on aircraft "67" is made as on aircraft "62" except for the engine cooling control, which is done according to the type of aircraft "63" and brake control, performed according to a new scheme ... The aircraft is equipped with an AP-42 autopilot. A heating system is installed according to the type developed for production Tu-2 aircraft.
Armament. Bomber armament is made under the rod wiring of the emergency release device. The aircraft provides the ability to suspend torpedoes and thousand-kilogram bombs on the front and rear holders and two-thousand-kilogram bombs on the middle and external bomb racks. The navigator is equipped with the OPB-1D, NKPB-7D and PTN-4 sights. Wing mounts are being redesigned to replace ShVAK cannons with Volkov-Yartsev, B-20 or NS-23 cannons.
As in many attempts to install diesel engines on our machines of the 40s, the lack of knowledge of domestic diesel aircraft engines crossed out the characteristics of the machines expected by designers when calculating. For example, it was supposed to reach a maximum flight range of about 5000 km, which was close to the range of the four-engine B-29 bomber, chosen in 1945 as a prototype for the future first Soviet post-war "strategist" Tu-4.
From January 12, 1946 to January 2, 1947, the experimental vehicle "67" was tested at the factory. The first flight took place in February 1946. During the tests, "67", basically stood on the ground with open engine hoods, in which the minders were digging, trying to get them to work normally. The car did not enter state tests. After the start of the serial construction of the Tu-4, the development of long-range versions of the Tu-2 stopped.
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