Aviation of Word War II

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SB-RK / Ar-2

Diving bomber

Arkhangelskiy

Arkhangelskiy Ar-2

The war in Spain showed the insufficient speed of the Soviet "high-speed bombers". An attempt to extend the life of the SB was the creation of an experimental MMN aircraft with M-105 engines. It was presented for state tests in September 1939. It differed from the SB bis 3 aircraft in engines, a more perfect shape of the forward fuselage, reduced by 8.5 sq.m. the area of ​​the detachable parts of the wing, a significantly increased area of ​​the flaps and horizontal tail, as well as the design of the detachable parts of the wing using beam spars and ribs stamped from a sheet.

Based on the experience of creating and flight testing the MMN aircraft, the Arkhangelsky brigade developed the latest modification of the SB - the dive bomber SB-RK (expanded wing, wing-radiators or SB with radiators placed in the wing), which completed the development of one of the most massive and famous combat aircraft of the world in the 1930s. It was as a dive bomber that the SB-RK type showed good results. The Red Army Air Force did not have such machines at that time, and the experience of fighting at the beginning of World War II in Poland and Finland showed both the need to hit small targets and the advantages of Germany, which had a specially designed single-engine dive bomber Ju-87.

Outwardly, the RK differed from the SB in the presence of aerodynamic brake grilles under the wing on its front spar, an improved shape of the engine nacelles, and a reduced height of the vertical tail.

The brake grilles, made of steel pipes, had an oval section. When entering into a dive, after opening the valve of the air system, the brake grids deviated to a position perpendicular to the flow. The release of the gratings was signaled to the pilot by mechanical indicators - “soldiers” emerging from the wing skin in the area between the 10th and 11th ribs. Entering into a dive was carried out by simultaneously deflecting up the trimmers of the elevators. When the bomb release button or the duplicate command button was pressed, the trimmers returned to their original position.

The front part of the fuselage of the SB-RK was completely redesigned, with an increased view to the pilot and navigator, providing direct communication between them (i.e., the pilot and navigator could exchange gestures or transmit something to each other). The pilot is shifted to the left to get a forward view when entering a dive through the glazing of the navigation cockpit, his instrument panel is mainly grouped on the right side of the cockpit. The pilot's canopy opens back up. The navigator's glazing area has been significantly increased and a second control with a folding steering wheel has been installed.



Bombers
SB
2M-103
SB-RK
No 2/281
Ar-2
No 1/511
Crew 3
Dimensions
Wing span, m 20.330 18.0 18.0
Length, m 12.770 12.780 12.625*
Height, m 4.735 4.700 4.700
Wing area, m² 56,7 48,2 48,2
Weight, kg:
Empty weight 4566 4735 5106
Loaded weight 6380 6300 6500
Powerplant
Engine M-103 M-105 M-105
Power, hp 2x960 2x1050 2x1050
Performance
Max speed, km/h at sea level 363.5 411 443
at altitude 433 480 505-512
landing 130 135 135
Time to level 5000m, min 8.9 8.55** 6.55
Wing loading, kg/m² 112,5 132 139-148
Service ceiling, m 8,800 10,100 10,500
Service range, km 800 - -

* - Under other data 12.640m

** - Under other data 7.1min

Armament. The aircraft was armed with 4 ShKAS machine guns (two of them at the rear upper and lower points) and could carry up to 1500 kg of bombs (with external suspension).

The NU-type bow gun mount (called NU-DB3F in a number of documents, since it is being developed primarily for a new modification of the DB-3F bomber) has one ShKAS machine gun with a supply of 500 rounds of ammunition. The ShKAS machine gun in this installation was mounted in a special ball head, the so-called. "Apple", allowing firing forward in a cone of 50 °. The machine gun is powered by a flexible sleeve from a cartridge box on the starboard side of the navigational cockpit.

The upper aft machine gun mount designed by Toropov with shelling only the rear hemisphere received the designation TSS-1 (high-speed aircraft turret), equipped with a K-8T collimator sight, has a supply of 1000 rounds of ammunition. The turret was a semi-circle (sector), along which a carriage with a machine gun head moved. In the stowed position, the machine gun was mounted on the port side, in the lantern there was a small cutout for this position. Upper lantern, so-called. "Turtle", when firing, moved back on rollers along the rails and partially rose up to protect the shooter from the oncoming air flow. The shelling from the TSS-1 could be carried out 90 ° to the left and right, up to 60 °, down to 30 °.

For the defense of the lower hemisphere, a retractable MV-2 turret with a ShKAS machine gun, with an OP-2L sight, with a supply of 600 rounds of ammunition, was installed on the SB-RK. The MV-2 was mounted on a special frame (cradle), which rose up in the stowed position. In the central part of the frame, in the area of ​​​​the machine gun handle, there was a copier limiter that prevented it from getting into its crutch wheel. When transferring the MV-2 to a combat position, the two lower glazed doors opened, after which the machine gun, together with the cradle, fell out. Aimed shooting from the MV-2 made it possible to fire at 30 ° to the sides, vertically from 4-5 to 55 °.

For dropping bombs of 250 kg or 500 kg caliber, new NP-1 holders were equipped under the center section of the SB-RK. The bombs were fastened in the area of ​​​​the center of gravity for one central lock and were additionally fixed with the help of side stops.

For aiming, the navigator was equipped with the NKPB-3 sight (for bombing at night and at low altitudes) and the OPB-1M sight. The pilot was equipped with a PBP-1 collimator sight, designed for dive bombing.

The weight of the empty aircraft was 4430 kg, the flight weight - 6650 kg, and with overload - 7800 kg. Its speed at an altitude of 4700 m was 480 km / h, cruising was 320 km / h, it gained 3000 m in 7.25 minutes. The ceiling was 10100 m. The flight range was 1500 km.

In accordance with the government decree on the renaming of combat aircraft, in the order of the NKAP dated December 9, 1940, the SB-RK was renamed Ar-2 (the first letters of the chief designer's surname and the even number "2", with which the numbering should have started all machines of any design bureau, if they were bombers, attack aircraft, reconnaissance aircraft and transporters). This is explained by the fact that all work on SB aircraft, starting from the design, was carried out by the team of A.A. Arkhangelsky - until 1936 under the leadership of A.N. Tupolev, and since the spring of 1938 independently at the factories.

Despite the fact that the flight speed of the Ar-2 has increased due to more powerful engines, a smaller wing area and improved aerodynamics of the airframe (as well as rate of climb and ceiling), the available information about the tests of the Messerschmitt Bf109E fighter purchased in Germany, said that that this was clearly not enough. Ar-2 was inferior to him in speed by more than 60 km / h. By the way, the German influence also touched the Ar-2, and not only in the concept of its appearance: such a technical solution as an automatic aircraft entry and exit from a dive, similar to that installed on the Ju 88, was mastered in production at the Moscow plant N 213 and was used on it and Pe-2.

According to an extract from the control log of the People's Commissariat of the Aviation Industry of the USSR "Dynamics of Aircraft Production" in 1940, 71 Ar-2s were produced. Decree of the Council of People's Commissars of the USSR and the Central Committee of the All-Union Communist Party of Bolsheviks "On the program for the production of aircraft and aircraft engines in 1941" N 2466-1096ss of December 7, 1940 established the program for the production of 1000 Ar-2 2M-105 in 1941 for the People's Commissariat of Aviation Industry, including 300 in the first quarter, 300 in the second, 250 in the third and 150 in the fourth. From the first quarter of 1942, the release of this aircraft was no longer expected. An extract from the control log of the People's Commissariat of the Aviation Industry of the USSR for the production of aircraft in 1941 indicates that 122 Ar-2s were manufactured at the 22nd aviation plant in the first quarter, including 100 in January, 20 in February, and in March - 2. "Plan of current military orders for the NPO, the NKVMF and the NKVD for aviation weapons for the II quarter of 1941" (Appendix N1 to the Decree of the Council of People's Commissars of the Union of the USSR N 908-383ss of April 12, 1941) contained information on the supply of 3 Ar -2 for the People's Commissariat of Defense. There are detailed data from the "Plan for the retraining of the flight personnel of the Red Army Air Force units on the new materiel for 1941." dated February 19, 1941 on the receipt by the relevant units of the Ar-2 aircraft and on the timing of the retraining of these units. 11 formations were to complete their studies by May 1, 1941. The new-generation Pe-2 bomber that replaced the Ar-2 was created in a big hurry, by converting a high-altitude long-range fighter into a dive bomber. It retained the great speed of its prototype, but compared to the older SB and Ar-2 had a small bomb load and a relatively short range.

Photo Description
Drawing Ar-2

Drawing Ar-2

Diving bomber Аr-2, February 1941

Diving bomber Аr-2 during official tests at February 1941

Ar-2 in standard protective colouring with number '3'

Arkhangelskiy Ar-2 in standard protective colouring with number "3", seized in the summer of 1941 German armies. Apparently the plane is completely serviceable.

In Detail

Bibliography

  • "The history of designs of planes in USSR 1938-1950" /Vadim Shavrov/
  • "Planes of Stalin falcons" /Konstantin Kosminkov and Dmitriy Grinyuk/
  • "Soviet aircraft of World War II" /V. E. Yudenok/
  • "The Soviet planes" /Alexander Yakovlev/