IL-2 with 37mm guns (II)
Il-2 with 37- mm by guns NS -37, official tests, June 1943. To the spring 1943 by only light armor of Wehrmacht, with which still we could successfully fight, using cannon armament, they remained only the lightly armored armored cars, armored carriers, and also self proelled guns and anti-tank SU (type Marder), created on the base of light tanks. Strictly light tanks in the composition pantservaffe at the eastern Front by this time already barely remained.
They were urged by more powerful against average and heavy tanks. Installation of gun NS -37 on Il-2 AM -38f Oruzheiniki will inspect NS -37 In this connection for the purpose of an increase in the anti-tank properties of attack aviation of the Red Army by the decision GKO № 3144 of 8 April, 1943, the plant № 30 was forced to let out two-place attack aircraft Il-2 AM -38f with two guns caliber 37 mm of yyP-eOKB -16 with the fire unit on 50 projectiles to the gun, without the rocket projectiles, with the bomb load 100 kg in the normal version and 200 kg in the shifting.
The ammunition of machine guns SHKAS 7.62 MM UBT remained as previous. During May month the plant had to prepare 50 new attack aircraft, during June - 125, during July - 175, also, from August turn to the production of all aircraft with the large-caliber aircraft cannons. Fire unit to the gun NS -37 consisted of cartridges with the armor-piercing - tracer (BZT-E") and fragmentation- tracer (OZT-E") projectiles.
Armor-piercing shells were intended for destruction of the ground armored targets, and fragmentation - for destruction of aerial targets.
Furthermore, for the new gun was developed the sabot, which ensures the penetration of armor with thickness to 50mm. During April the 30th aircraft factory prepared 5 Il-2 with NS -37 of advance run, one of which ( № 302349) on 27 May entered official tests in NII - SCIENTIFIC RESEARCH INSTITUTE VVS KA. Latter after the execution of 26 flights with film 11 hour. 35 min. successfully were completed to 22 June, 1943, (chief test pilot Of a.I.Kabanov, the chief engineer Of v.S.Kholopov, the pilots of circling Major A.K.Dolgov and the engineer major OF A.V. Of sinel’nikov).
The produced to the State tests attack aircraft was differed from series Il-2 only in terms of installation of two guns NS -37 with the fire unit on 60 projectiles to the stem and absence PC. normal bomb load - 200 kg. The band feed of guns NS -37 allowed the specialists OF OKB Of s.V.Il’yushina to place them directly on the lower wing surface with the use of structurally very simple and quick-release fastening. Guns were shut by the relatively small fairings, each of which consisted of two easily opened folds. Fire unit to each gun was plotted directly in the sections of wing.
The weight of one gun NS -37 with the fire unit was 256 kg. With the gross weight of 6277 kg the maximum speed of attack aircraft at the height of 1320 m was 387 km/h, in the earth -375 km/h the service ceiling of new aircraft did not exceed 5200 m, in this case the duration of ascent to the height of 1000 m was 3 min.
The maximum flying distance of attack aircraft did not exceed 685 km. In comparison with the the series of by the armed guns SHVAK or Vya, Il-2 with NS -37 and with the bomb load in 200 kg it became more inert more complex on the turn and on the chandelle. Worsening in the piloting characteristics of new attack aircraft, just as Il-2 with the guns SHFK-E", was connected with the large spread of mass on the wingspan and the presence of the fairings about the guns, which worsen general aerodynamics of aircraft. In entire range of centerings Il-2 with NS -37 it did not have longitudinal stability, which substantially decreased accuracy of shooting in air.
The latter was aggravated by the strong recoil of guns . According to the data OF NII - SCIENTIFIC RESEARCH INSTITUTE AV VVS KA (letter of the chief OF NII - SCIENTIFIC RESEARCH INSTITUTE AV Major General m.V.Gurevich from 19.11.1943 g. to the name Of s.V.Il’yushina) the maximum recoil force, which acted during about 0,03 s, on the ground-based machine tool (existing at that time equipment did not make it possible to take the measurement of the force of on the aircraft shooting in air) it composed the very significant magnitude - on the order of 5500 kg, and the average value of recoil force approximately was equal to 2500 kg. all this it led to the large scattering of projectiles with the shooting in air. The range tests, carry ouied in NII - SCIENTIFIC RESEARCH INSTITUTE AV VVS KA, showed that shooting from the aircraft Il-2 of the guns NS -37 it is necessary to conduct only by short bursts by length not more than 2-3- X of shots, since with the shooting simultaneously of two guns as a result of the lack of synchronation of their work aircraft experienced significant pushes, pecks it were brought down from aiming line.
Correction into the aiming in this case in principle was possible. With the shooting of one gun impact on purpose was only possible first shot, since attack aircraft was turned to the side of the shooting gun and correction into the aiming became practically impossible. However, the defeat of pinpoint targets - tanks, armored cars, automobiles and so forth with the normal work of guns was possible. In this case the entries into the tanks were obtained only in 43% of departures, and the number of entries to the spent fire unit composed 2,98%.
The analysis of the results of range tests shows that defeat 37- mm by projectile BZT-E"from the aircraft cannon NS -37 from the aircraft Il-2 light German tanks, the armored cars and the armored carriers of all types, and also the type of Wespe and anti-tank SU of the type of &.tsuot;.Marder-ll&.tsuot; and &.tsuot;.Marder-lll&.tsuot; it was ensured from the distance to 500 m from any direction. Average German tanks of type StuG 40 (the assault gun), Pz. Ill Ausf L/M and Pz. THE IV Ausf G/H, and also appeared are later than StuG THE IV and tank destroyer Jgd Pz IV/70 with the thickness armor on the boards to 30 mm could be defeated by the BZT-E ammunition from the distance to 500 m from the planning at angles of 5-10° from the heights of 100 m. In this case the attack should have been produced on the side or from behind, conducting shooting at the board or at the aft body and tower of tanks. The entries of the projectiles of this gun into the rollers and other details of the undercarriage of the tanks of all types produced the essential destruction, which render inoperable the latter.
In the conclusions of report on official tests separately attention was paid to the fact that the crew, which flies on the aircraft Il-2, armed by guns NS -37, must pass special preparation in conducting of aiming fire in short bursts at the pinpoint targets (separate tanks, motor vehicle, etc.). To the thirtieth aircraft factory NKAP and OKB -16 nkv one should have urgently established to the gun muzzle brake. Furthermore, it was indicated that Il-2 with NS -37 it was necessary to experience with the fire unit to the guns on 50 projectiles and the normal bomb load in 100 kg, as it was recorded in the decision GKO. Subsequently all series Il-2 with NS -37 were let out precisely in this version of armament. Technical flight data of aircraft somewhat were improved. With the gross weight of 6160 kg the maximum speed at the height of 1320 m was 405 km/h, in the earth - 391 km/h. Duration of ascent to the height of 1000 m - 2,2 min.
As is evident, with the installation of guns NS -37 to the two-place Il-2 the designers encountered the same problems, as with the installation to one-place guns SHFK-E". However, the basic means of fight with the German tanks during this period of war became the antitank bomb of acumulative effect ( I.e shaped charge) with a weight of 1,5 kg in the overall sizes confronting in the arsenal VVS KA of the aircraft bomb with a mass of 2,5 kg - PTAB-2