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I-17

Fighter

Polikarpov

Polikarpov I-17

The I-17 (TsKB-19) was displayed at the 15th Paris Air Show, Le Bourget, in November 1936 together with the Tupolev ANT-25 record-breaking aircraft (URSS-No25) and an ANT-35 airliner (URSS-No35).

Few of the combat pilots actually knew about the existence of the experienced I-17 fighter, in fact - the version of the I-16 with an inline liquid-cooled engine. At first, it developed after the I-16 with a difference of about one year, but time passed and the time gap in the fate of the two machines steadily increased. The I-16 was serially built and continued to improve, while the "seventeenth" remained in the experienced category. Why didn't the I-17 go into big life? There is no definite answer, there are many reasons and circumstances that influenced the fate of this interesting aircraft.

Since Polikarpov reasonably hoped to achieve a maximum speed of 500 km/h on the new car, the contours were compressed to the limit and the aerodynamics of the fuselage were improved. The decrease in the midsection of the latter and, therefore, the narrowness of the cockpit forced the designers to place the pilot at a large inclination to the vertical - the angle of the pilot's seat was 22°. The higher weight of the propeller-engine group (VMG), together with the cooling systems, should not have impaired maneuverability, so the wing span increased to 10 m in comparison with TsKB-12, the wing area - up to 17.7 m². The specific load on the wing was 102 kg/m² and was practically equal to that of the I-16 type 5 (100 kg/m²).

In parallel with the design of the TsKB-15, which received the official designation I-17 in the Air Force, in the second half of 1933, work was carried out on its two-seat version - DI-7.

The aircraft was built during 1934. Structurally, it largely repeated the I-16. The wing with spars made of steel, chrome-molybdenum pipes with a duralumin transverse set and linen sheathing was equipped with split differential ailerons, capable of deflecting downward on landing and partially playing the role of flaps. Two retractable water radiators in the wings, indicated in the design version, were replaced with one ventral, also retractable. This arrangement led to the landing gear layout with retraction "from the axis" of the aircraft. Fuel tanks with a total capacity of 360 liters were located in the leading edge of the center section, which made it possible to partially unload the wing and more efficiently use the internal volumes of the engine space in the fuselage. In part, this decision points to the original idea of ​​installing an aircraft rapid-fire cannon in the fuselage, firing through the hollow shaft of the propeller hub. Nevertheless, the armament of the first prototype (as well as the second one) consisted of four ShKAS machine guns placed in the detachable parts of the wing.

I-17 Polikarpov
TsKB-15 TsKB-19 TsKB-19 bis
Crew 1 1 1
Dimensions
Length, m 7.4 7.365 7.425
Wing span, m 10.0 10.0 10.0
Wing area, m² 17.7 17.65 17.65
Powerplant
Hispano-Suiza HS 12Ybrs HS 12Ybrs M-100A (cannon`s)
Power, hp 800 800 750
Weight, kg:
Empty weight 1350 1560 1465 (1533)-Settl.
Maximum takeoff weight 1823.29 1916.22 1950 (2020)-Settl.
Performance
Maximum speed, km/h km/h 455 485  
at altitude, m 3,380    
Service ceiling, m   9,700  
Armament
Machine guns 4×ShKAS 4×ShKAS ShVAK & 2×ShKAS

I-17 (TsKB-19), the second prototype. This device was built taking into account the tests of TsKB-15 in 1935. According to the documentation accompanying the construction of TsKB-19, the plane was equipped with a Hispano Suiza engine "HS 12Ybrs with a propeller with a diameter of 3.0 m. However, already in preparation for testing, the M-100 engine is indicated in the materials of the weight team No. 6 of the Central Design Bureau. It is quite possible that the engine was replaced, but at the same time, for a number of reasons (the fact that the engine plant had mastered it, the first serial ones were produced, the desire to use the domestic designation, etc.), the French "Hispano" could be called M-100. One way or another, in the future, the M-100 was always indicated.

As for the indicated diameter of the propeller - 3.0 m - in this case, it is not completely clear. The three-meter diameter of the propeller seemed the most favorable for a fighter with a wingspan of 10.0 m. However, the HS 12Ybrs and the M-100 launched into production with the existing gearbox were guided by a two-blade propeller with a diameter of 3.4 m (just right for SB). That is why TsKB-19 had a chassis height that allowed a 3.4 m diameter propeller to be installed with a minimum safe clearance between the blade tip and the ground.

Unlike the first prototype, TsKB-19 had a chassis of a different design - cleaning was carried out in the direction "towards the aircraft axis". The new chassis layout made it possible to bring the track in the parking position to 2,868 m. The produced water-cooling radiators were placed immediately behind the chassis in the root of the center section. Ailerons decreased in scope and lost the ability to differential deflection - now the role of landing mechanization was played by deflected flaps with an area of ​​1.75 m².

On September 16, 1935, the factory pilot Chkalov made the first, 8-minute flight by plane at exactly 2 pm. In his usual laconic manner, the tester wrote down: "Achieved. Flight performance is good. No vibrations noticed."

I-17 (TsKB-19bis), third experienced. Sometimes this machine is called I-176is, in the future we will use this to simplify the story. The lead engineer for it was D.L. Tomashevich.

On the third prototype, it was necessary to implement plans to install a rapid-firing air cannon located in the collapse of the engine cylinders and firing through the hollow shaft of the propeller. To define this entire structure, a short combination was used - "motor-gun".

Despite the interest shown by the Air Force, in 1938, preference was still given to air-cooled machines. The design and construction of I-180 Polikarpov, I-28 Yatsenko, I-220 Silvansky and I-207 Borovkov and Florova began.

Only with the appearance of the M-105 engines and in anticipation of the M-106, and then the M-107, in 1939, full-fledged work began on the creation of aircraft for these power plants. Of almost a dozen different projects, the most viable were the I-26 (Yak-1) and I-301 (LaGG-3), which finally put an end to this protracted history.

Photo Description
Drawing I-17bis

Drawing I-17bis

The third prototype I-17 (TsKB-19bis) during cannon armament tests, 1937.

Bibliography

  • "The history of designs of planes in USSR 1938-1950" /Vadim Shavrov/
  • "Aviation # 4 2001 " /Michael Maslov/