Air fighter of tanks VIT-2

In the spring of 1938, an improved version of the air tank destroyer, VIT-2, appeared, which went through a full cycle of tests.

VIT-2 - development of VIT-1. Spaced vertical tail, ShVAK cannon on the rear turret. The wing of the "Clark Y" profile with relative thicknesses of 14% at the root and 6.35% at the ends, wing elongation - 6.67, tapering - 3.53, developed fairings - all this is the same as in VIT-1. Engines M-105 1050hp each. The landing gear wheels, closed together with the struts with convex fairings, were retracted (pneumatic drive) into the rear compartments of the engine nacelles. The cockpits of the navigator, pilot and gunner have large glazing surfaces.

The armament was powerful - two ShVAK-20 cannons, mobile, in the nose and on the turret, two 37-mm cannons and two ShVAK cannons in the wing, stationary, against tanks and two ShKAS machine guns in the lower dagger installation; bombs, as in VIT-1. The prototype plane had two ShVAK cannons - at the navigator and at the gunner. Destructive overload in case of Ak - 10.9 according to static tests.

The first flight was on May 11, 1938 (V.P. Chkalov). Experienced by BN Kudrin (factory tests) and PM Stefanovsky (state tests).

Note that it was NN Polikarpov who was the first to take on the whole burden of mastering and fine-tuning the M-105 motors that were completely "raw" by that time. It all started with a scandal related to the fact that the engine plant sent M-105 motors completely unusable to the Polikarpov Design Bureau. In the period from August 2 to September 10, 1938, repeated factory tests of VIT-2 2M-105 were carried out. Most of the time was spent not so much on the actual testing of the aircraft as on fine-tuning the M-105 engines. With a flight weight of the aircraft of 5600 kg at an altitude of 4500 m, a maximum flight speed of 513 km / h was obtained. By this time it was an outstanding result, but the NKAP did not support Polikarpov in the work on VIT-2. As the leading engineer for the VIT-2 aircraft from the Air Force Research Institute P. M. Nersisyan wrote to the director of plant No. 84 Osipenko, it was even forbidden to show the aircraft to the Air Force leadership. And only after Nersisyan sent a letter to Marshal K. E. Voroshilov, the plane was shown to the Air Force Chief of the spacecraft Y. V. Smushkevich. After inspection of the plane by Smushkevich, on his initiative, factory tests were interrupted: VIT-2 was transferred to the Chkalovskaya airfield at the Air Force Research Institute for display to the Government. After showing the car to the Government, it was left at the Air Force Research Institute for joint tests. The test brigade from the Air Force Research Institute included the leading engineer Nersisyan, the leading test pilot PM Stefanovsky, the test navigators P. Nikitin and P. Perevalov. From September 13 to October 4, 1938 VIT-2 passed state tests. There were 35 flights with a total duration of 13 hours 40 minutes. With a flight weight of 6300 kg at an altitude of 4500 m, a speed of 483 km/h was obtained.

Note that the military turned the VIT-2 in every possible way to use it as a dive bomber, which is why the name SPB (high-speed dive bomber) appeared in the test report materials. NN Polikarpov agrees to the name SBP (high-speed bomber, also a dive if necessary).

Such caution is understandable - the BSB aircraft, on the basis of which the VIT-2 arose, was developed as a high-speed bomber, and when it turns into a dive bomber, which, of course, must meet more stringent strength standards, it will inevitably have to sacrifice many flight characteristics.

It so happened that in the documents of the Air Force the plane was called SPB, and in the documents of the NKAP - at the beginning SBP and only later - the same SPB.

There was a VIT project in the version of an aircraft for long-distance flights, with two M-105 engines, without weapons, with additional tanks. The estimated range is 7900 km at a speed of 350 km/h and 6200 km at a speed of 500 km/h. The project was not implemented.

Photo	Description
	Drawing VIT-2
	Polikarpov VIT-2. Cockpit and landing gear of VIT 2

Bibliography

• "The history of designs of planes in USSR 1938-1950" /Vadim Shavrov/
• "Planes of Stalin falcons" /Konstantin Kosminkov and Dmitriy Grinyuk/
• "The Soviet planes" /Alexander Yakovlev/