Military Review

IL-20: Stormtrooper with extreme visibility

IL-20: Stormtrooper with extreme visibility

At the end of the 1930-x - the beginning of the 1940-s, the main and practically the only tactical tactic for attack aircraft was an attack from horizontal flight at extremely low altitudes (from a strafing flight). And at that time, and later - in the 1950-x, when designing single-engine attack aircraft using the traditional layout of their layout, the designers had to provide a fairly good forward-down view. For airplanes with air-cooled engines, this problem turned out to be particularly difficult.

Experienced attack aircraft IL-20

A review in this direction is necessary so that the pilot can quickly and correctly assess the situation on the battlefield, identify targets, determine the opposition of enemy ground weapons, select a target and maneuver for its attack, make aim, and have time to use the offensive weapons as efficiently as possible. Since attack aircraft were often used as light bombers, a good downward view, directly under the aircraft, was also important to ensure accurate bombing.

The angle of view of the TS-2 attack aircraft (the most visible among our first armored attack aircraft) did not even reach one degree. When flying at an altitude of 15 m, the pilot could see targets that were at a distance of at least 1000 meters ahead. This completely eliminated the shooting of machine guns.

When creating the Su-6 aircraft, in order to get a more or less satisfactory forward-down view, P.O. Sukhoi spent a long time looking for a place under the engine and carefully chose the contours of the engine hood.

S.V. Ilyushin to improve visibility on BSH-2 (IL-2) was forced to raise the seat of the pilot, lower the engine relative to the axis of the aircraft, pay much attention to the contours of the engine hood. As a result, he provided a forward-downward viewing angle of about 8 degrees.

All serial attack aircraft did not have a review down under the plane. The exception was IL-2, equipped with a special periscope, which, however, did not receive further distribution.

The way out was found using the time delay for dropping bombs, either with the help of special sights and temporary mechanisms, or by marking marks on the structural elements of the aircraft. Sometimes, in order to increase the effectiveness of the Il-2 aircraft from a strafing flight, it was necessary to make them “sighted” with the help of target airplanes for attack aircraft (STSUS). In this capacity, flight bombers and search for targets at medium altitudes, the SB, Pe-2 bombers, and subsequently the specially selected IL-2 crews were used. After the discovery of the object of attack, the navigator or pilot STSUS dropped bombs and thereby designated it.

At the beginning of the 1940-ies in the USSR, attempts were made repeatedly to create attack aircraft with improved forward-down visibility and the possibility of firing at targets in this sector with mobile cannon-machine gun installations. However, both the multipurpose single-seat aircraft of the “OPB” battlefield, designed by S.А. Arkhangelskogo, G.M. Mozharovsky, I.V. Venevidov, and armored attack aircraft "MS" S.V. Ilyushin, using unconventional design solutions, did not go into the series.

Development of attack aircraft IL-20

Side-shift IL-20 with a color option

Comparison of viewing angles of attack aircraft Il-2 and Il-20

They returned to work in this direction only after the end of the war. In accordance with the Decree of the USSR Council of Ministers on 11 in March 1947, the Ilyushin Design Bureau was given the task of creating a new attack aircraft with slightly higher (compared to IL-10) flight data, more powerful cannon and missile weapons, and improved visibility and booking. At the end of 1947, the designers completed the development of a single-engine armored two-seater attack aircraft with a liquid cooling engine MF-45ш. The original layout was used, which provided an excellent forward-down view. Unusual and gun armament. The draft design of the IL-20 MF-45 aircraft was sent in February to 1948 at the Air Force Research Institute.

The USSR Council of Ministers resolution on the construction of prototypes of the Il-20 was adopted on 12 on June 1948. The conclusion on the draft design was approved on 19 on June of the same year by the Chief Air Force engineer I.V. Markov. Major engineer SGFrolov was appointed responsible for the aircraft. The purpose of the attack aircraft was formulated as follows: "To suppress and destroy manpower and technical equipment on the battlefield and in the tactical depth of the enemy's position." It was proposed to make two projects with different variants of offensive and defensive weapons.

Under the scheme, the first version of the aircraft was a low-winged liquid-cooled engine with a four-blade propeller with a diameter of 4,2 meters. The cockpit was located unusually - directly above the engine - and was pushed forward to the limit. The front of the cab was formed at an angle of 70. long windshield 100 mm thickness. One end of it almost rested against the bushing of the screw. This provided a forward-down view of the 37 degrees sector, and when diving at an angle of 40-45 degrees. the pilot could see targets that were almost directly under the plane. Behind the cockpit were oil and gas tanks. Behind them was the gunner’s cabin, remotely controlling the 23-mm cannon, housed in a special IL-WU-11 mobile unit with a hydraulic drive and a mechanism for bypassing the gun barrel along the fuselage and tail unit contour weapons).

Layout IL-20

Projection attack aircraft Il-20

The Il-VU-11 was designed by the Ilyushin Design Bureau. It provided large angles of fire in the upper part of the rear hemisphere: 80 degrees. - upward and 90 degrees. - right and left. The maximum speed of movement of the weapon in the mobile installation was 4-45 degrees / sec. Since the lower quarter of the hemisphere was completely unprotected by the gun mount, a cassette for 10 aviation grenade AG-2, thereby organizing partial protection.

The tail plumage was single-chin, the wing and horizontal plumage were trapezoid in plan. Water and oil radiators were located in the center section, the engine air intake was located in the lower part of the fuselage, in the area of ​​the front wing trim.

The cockpit of the pilot and gunner, engine, fuel supply and lubrication systems, cooling system were inside the armored box. The total weight of metal armor was 1840 kg, and transparent - 169 kg. The cockpit had, in addition to the frontal, two side armored glass with a thickness of 65 mm and a rear armored glass, also 65-mm. In the upper part of the cabin from the sides of the lantern were armor plates with a thickness of 10 mm; the sides of the cockpit, the rear bulkhead behind the pilot were 10-mm, and in the upper part - 15-mm. The shooter behind and above was protected by 100-mm bulletproof glass, front upper sheet behind the gas tank and onboard 6-mm sheets, lower cabel armor sheet in 8 mm, upper and lower shielded armor 8 + 8 mm thick.

Motor booking included an armored car made of 6,8 and 12 mm thick sheets, which protects it well in front, bottom and sides. The top sheet of the gas tank with a thickness of 4 mm, the side sheets in 6 mm and the plates behind the tank in 10 mm completely covered it from those sides where there was no other armor protection. The radiators were covered from the sides with sheets in 4 mm, a radiator shield inside the motor armor in 6 mm, bottom armor plates 8 mm thick, and two 10 mm radiator armors. As you can see, the reservation was made exceptionally strong. It mainly provided protection against 12,7 mm bullets and, to a significant extent, against 20-mm aviation cannons. Compared to IL-10, the thickness of metal armor increased on average by 46%, and transparent - by 59%. The offensive weapons in the first version included two 23 mm caliber wing cannons for firing forward in a dive or planning and two 23-mm cannons mounted in the fuselage at an angle of 22 degrees. to the flight line - for firing targets with a strafing flight. The normal bomb load was 400 kg, while overload was 700 kg. Under the wing in the transshipment version, the suspension of four single-charge jet guns ORO-132 was provided.

In the second offensive version, it was planned to use one 45 caliber mm gun, two 23-mm guns and six ORO-132. The aircraft was equipped with a perfect flight and navigation and radio communications equipment, thermal de-icing system. This widened its use in bad ones.

In the conceptual design was developed and the second version of the defensive armament of the aircraft IL-20. There, instead of the upper IL-VU-11 installation, the IL-KU-8 mobile aft gun mount, located in the tail section of the aircraft, was used. It protected the aircraft in the rear hemisphere from enemy fighter attacks from all directions. In the IL-KU-8, the shooter at the rear was protected by bulletproof glass 100 mm thick, from the sides - by bulletproof glass in 65 mm. Curved along the contour of the rifle installation, armor 10 mm thick, side 6-mm and rear 4-mm armor plates provided reliable protection for the shooter in this variant.

The idea remained unrealized.

Despite a number of original ideas, the draft design of the IL-20 was rejected as inconsistent with the decision of the USSR Council of Ministers and the tactical and technical requirements. This concerned the basic flight data and weapons.

The main drawback was the low flight speed of the aircraft, which turned out to be even lower than that of the serial IL-10. Offensive weapons also did not satisfy the customer.

It was noted that the fire power of the IL-20 is less than that of the IL-10. At the same time, it was possible to fire only from two cannons - either wing or fuselage. The expediency of applying the latter was not in doubt, but there was a desire to have mobile units. Along the way, we say that quite successful developments in this field that were already available at that time were G.M. Mozharovsky and I.V. Venevidov were not used. When loading PTAB, the bomb load was only 300 kg.

A significant increase in the midsection of the fuselage and its lateral surface led to a deterioration in the aerodynamics of the aircraft, an increase in the flight weight, and an increase in the possibility of enemy fire damage. Since the distribution of the armor installed on the aircraft was carried out over a large surface, the experts of the Air Force Scientific Research Institute did not see an improvement in booking compared to the IL-10. Extremely complicated operation of the VMG due to irrational ways of approaching the motor and its units. With all the work related to the shooting of blocks or their covers, it was necessary to disassemble the engine itself from the aircraft. All work on the motor mechanic had to perform in the upside down position. The pilot got into the cockpit only when the engine was not running. At emergency leaving there was a danger of getting under the screw.

The main positive factor was considered only an excellent forward-down view (although only in a very narrow sector). The overview to the side and forward was the same as that of the IL-10.

The layout of the IL-20 was presented to the mockup commission in July 1948. In the protocol, which was approved by 21 July 1948, Air Force Marshal K.A. Vershinin, the motor was already called M-47. The model in the variant with IL-VU-11 was declared incomplete. The review down-to-side turned out to be worse than the IL-10. The cab was located too close to the propeller, which is unsafe when it was left, and during an emergency landing, the propeller blades are likely to be damaged by the propeller blades. There was no emergency reset of the flashlight and protective anti-coiling device. The layout scheme complicated operation.

Among the positive qualities, there was an excellent forward-down view and the presence of guns firing at an angle downward and giving the opportunity to attack area targets from horizontal flight at altitudes from ramming flight to 700-800 meters.

The Commander-in-Chief of the Air Force did not consider the construction of the IL-20 necessary until the final approval of the layout. However, the aircraft in the first version produced. He had four movable wing 23-mm guns W-3 designed by B.G. Spit with 900 ammunition shells. In the IL-VU-11 mounted mobile gun W-3 with ammunition 200 shells.

Factory tests began on November 20 1948 g. The first flight at the beginning of December 1948 was made by the pilot V.K. Kokkinaki. During the test, the aircraft showed the maximum flight speed of all 515 km / h at an altitude of 2800 meters. Due to low flight data, failure to comply with the requirements for armament and the lack of knowledge of the M-47 engine designed by M.R. Fleece work on IL-20 in accordance with the Decree of the Council of Ministers of the USSR dated 14 in May 1949 was stopped.

The plane was examined by the deputy commander for combat training and noted the following shortcomings:

• cockpit and arrow split fuel tank;
• dive issues not worked out;
• the effectiveness of fire extinguishing in the area of ​​the gas tank was not ensured;
• installed four guns ahead instead of six, and others.

S.V. Ilyushin worked out two more (except for those already discussed above) variants of the Il-20, with an IL-10 arrangement, the flight data of which was slightly higher. But all this remains unrealized.

The final attempt to create an attack aircraft with an improved forward-down view was the conceptual design of the Sh-218 armored two-seater attack aircraft with a powerful X-shaped motor M-251 designed by SM Alekseev. But its characteristics were considered unsatisfactory.

Thus, a fairly good overview of the forward-down single-engine attack aircraft could not be obtained. In the IL-20 aircraft with the M-47 engine, this was achieved at the cost of a loss in many other parameters, which prevented the car from being taken into the series. It can be concluded: the hope to solve the problem of a forward-down review due to unconventional layouts of single-engine attack aircraft did not materialize.

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  1. Gamdlislyam
    Gamdlislyam 28 May 2016 05: 56
    Article is good, plus to the author.
    I read the books indicated by the author. Very good, especially for those who are not familiar with the history of the development of attack aircraft.
    The fate of the helicopter attack aircraft was influenced by the rapid development of jet aircraft. Already in 1950 at the Design Bureau of Ilyushin S.V. They began to work on a project of a two-jet attack aircraft, which took off already in 1953.
    1. lelikas
      lelikas 28 May 2016 11: 27
      Quote: Gamdlislyam
      Article is good, plus to the author.

      Brevity is the soul of wit - This expanded the possibilities of its use in the bad. laughing But articles on the profile of the site - please! +
      1. Uncle
        Uncle 30 May 2016 14: 13
        When flying at an altitude of 15 m, the pilot could see the targets
        WIG sort of. wink
        1. mirag2
          mirag2 31 May 2016 08: 58
          Very interesting plane. I heard about it. Thank you. Interesting.
  2. igordok
    igordok 28 May 2016 07: 04
    Thank you.
    Once again I remember, "A beautiful plane flies beautifully." At first glance, the Il-20 is ugly. Even though he has great ideas.
  3. Mikhail Matyugin
    Mikhail Matyugin 28 May 2016 07: 12
    Interesting material about an unusual attack aircraft. But after the war, such build in the presence of many IL-10, which are rapidly becoming obsolete? In general, it’s right that they did not begin to commission.
    1. Evdokim
      Evdokim 28 May 2016 15: 20
      I agree. The time has come for jet aircraft.
      1. apro
        apro 29 May 2016 07: 11
        Quote: Evdokim
        I agree. The time has come for jet aircraft.

        But for some reason, amers did not prevent the use of piston strike aircraft before the Vietnam War, cheaply and angrily, in Afghanistan we would not have been prevented from using such cheaply and angrily and had a circle of tasks. And today the use of toucan in counterguerrilla operations is more than justified.
  4. Volga Cossack
    Volga Cossack 28 May 2016 07: 40
    interesting aircraft - sorry late ......... the era of reactive has come .. yes and IL-10 has already been much mastered and ......
    1. zyablik.olga
      zyablik.olga 28 May 2016 09: 19
      Quote: Volga Cossack
      interesting aircraft - sorry late ......... the era of reactive has come .. yes and IL-10 has already been much mastered and ......

      If I'm not mistaken, at the end of the 50's, all of the IL-10s were written off and our country was left without armor for a long time.
      1. Gamdlislyam
        Gamdlislyam 28 May 2016 11: 36
        Quote: zyablik.olga
        in the late 50s, all IL-10 were decommissioned and our country was left without armored attack aircraft for a long time.

        Dear colleague Olga, during the Korean War, the North Korean IL-10s were knocked out very quickly, while there were only 11 out of 90 available ferry fighters for jet fighters. Attack aircraft proved to be easy targets for anti-aircraft gunners. For night flights, the IL-10 was absolutely unsuitable. The linen-wooden Po-2, operating at night, turned out to be much more effective (a headache for the Americans) than the armored IL-10.
        As a result of the analysis of these events, the USSR Ministry of Defense made a decision in April 1956 to disband the assault regiments. Instead, regiments of fighter-bomber aviation were created, the MiG-15 and MiG-17 began to enter service.
        And, only with the advent of the Su-25 attack aircraft, in our country, in the second half of the 80s of the last century, assault regiments began to form again.
        1. Mikhail Matyugin
          Mikhail Matyugin 29 May 2016 14: 21
          Quote: Gamdlislyam
          IL-10 was absolutely not suitable for night flights. The linen-wooden Po-2 operating at night turned out to be much more effective (a headache for Americans) than the armored Il-10.

          No, it's just that the Yankees had a very perfect anti-aircraft artillery. And as regards the real combat effectiveness of Po2, this is ridiculous, nothing more than a "headache", "harassing bomber", it cannot be compared with the force of fire of the Il-10.
      2. Volga Cossack
        Volga Cossack 28 May 2016 12: 31
        then such a concept prevailed - the attack aircraft eliminated - and all countries, in my opinion - the Americans, for example, the invader even re-qualified as a bomber, before that he was a heavy attack aircraft ... i.e. A-ATTAC category - the attack aircraft was removed - thrown into the B-BOMBER category ....... a return to the attack aircraft concept and the subsonic - su-25 occurred due to the inability to effectively use too high-speed fighter - bombers.
  5. Dimon19661
    Dimon19661 28 May 2016 07: 53
    Good article, read with pleasure +.
  6. Bosk
    Bosk 28 May 2016 10: 38
    I just thought that if you slightly "modernize" it (weapons, engine, electronics), then today, at least for "internal operations", such a "piston" can be used, because today between helicopters and jet aircraft sometimes there is such an option that "reagent" for a lot ... and a helicopter for a little ...
    1. Gamdlislyam
      Gamdlislyam 28 May 2016 11: 51
      Quote: Bosk
      I just thought that if you slightly "modernize" it (weapons, engine, electronics), then today, at least for "internal operations", such a "piston" can be used, because today between helicopters and jet aircraft sometimes there is such an option that "reagent" for a lot ... and a helicopter for a little ...

      Dear colleague Vlad, we have enough Su-25 attack aircraft or attack helicopters for "internal operations". The former operate from high altitudes according to the "hit and run" principle, the latter - from ultra-low-key targets so as not to be hit by MANPADS or small-caliber anti-aircraft weapons. A living example, the war in Syria.
      1. Urfin
        Urfin 28 May 2016 21: 40
        I was always wondering why piston armored aircraft are not used instead of or in conjunction with helicopters. Helicopters have only one plus in front of piston attack aircraft - the ability to land on a platform with a diameter of several meters, Everything else - profitability, payload, cost, etc. - in favor of the attack aircraft. the tasks are the same. Making a dirt airfield is not difficult.

        Can someone correctly explain?
        1. pimen
          pimen 29 May 2016 17: 43
          I can’t competently, although the question is, of course, interesting. Probably, it would be more correct to ask not piston, but rotor motors.
          Compared to turbines, reciprocating engines of comparable power have a greater, progressively greater weight. Piston airplanes - only screw ones - are steamed, this gives a greatly reduced gain in profitability with an increase in speed to 500-700km / h (adjusted for altitude). With an increase in speed to 900km / h, the jet drive seems to overtake the screw drive in all respects, at all heights (well, except for takeoff)
  7. rubin6286
    rubin6286 28 May 2016 12: 41
    The article is interesting, informative. The plane was unsuccessful, despite all the efforts of the designer who completed the technical task and did not go into the series. About the same situation was with Tupolev with its Tu-91, which for its time was a rather interesting machine.
    1. Gamdlislyam
      Gamdlislyam 28 May 2016 18: 19
      Quote: rubin6286
      Tu-91, which for its time was a rather interesting machine.

      Dear Victor Vilenovich, the Tu-91 was developed on the instructions of 1952, as a deck bomber and attack aircraft. However, under Khrushchev N.S., the construction of aircraft carriers and large warships was abandoned in favor of the development of rocket technology. Tu-91 was no longer needed by the Soviet Navy. The topic has been closed.
      1. rubin6286
        rubin6286 29 May 2016 10: 45
        It's bookish. In fact, NS Khrushchev personally "closed the topic", having neither the knowledge nor the experience of a statesman, which later served as the basis for his dismissal at the Plenum of the Central Committee. Unlike the IL, the Tupolev machine was properly tested and brought to life. Were investigated many aspects associated with the use of turboprop and coaxial propellers. Deck aircraft - the machine is initially compact. You don't need an attack aircraft and a torpedo bomber, in the classical sense of this meaning, but after all, we have 4 fleets and a flotilla, but we did not have (and still do not) basic patrol aircraft. It was possible to offer a variant of a special anti-submarine aircraft, a Border Service aircraft. They were not there either, but there was Khrushchev and his friends - Yenko, Tymoshenko, Grechko. He made some marshals, and Zhukov laughed and never invited them to his birthdays. The Americans and the British were smart enough, along with the development of jet aircraft and missiles, not to mindlessly bury piston and turboprop machines. In 1952, the British had the world's best AWACS "Gunnet", carrier-based torpedo bombers "Wyvern" with coaxial propellers. The Americans used the Neptune patrol aircraft and the Trekker anti-submarine aircraft, the famous Skyrader.
        Many topics were then “closed”. An especially interesting "topic" was the reduction of the army by 1 million 200 thousand people, as a result of which the front-line officers of the regimental and division level "flew" from the army without a pension. There are lines. which at that time were attributed to R. Rozhdestvensky:
        "If you get fired, don't shit,
        Hold your nerves in check.
        There is a pension - send everyone to x ...,
        No - go to p ....! ".
        Instead of equipping with missile weapons, the cruisers, front-line bomber and fighter aircraft “crumbled”. Were Khrushchev in power until 1965-67, there would be no Tu-16 and Tu-95, not to mention the promising Tu-22 and so on.
        V. Vysotsky said about those times:
        “Khrushchev Nikita is our good father!
        Under him, we built factories, blast furnaces, thermal power plants,
        When he flew to the moon, when he plowed virgin lands,
        Khrushchev Nikita is our good father!
        But soon, for some reason, he - of that ...
        Then we learned the whole truth about him:
        That he ruined the farm
        what he awarded Nasser
        and it would be better for us, of course. without him! ”
  8. iouris
    iouris 28 May 2016 13: 32
    When flying at low altitude with high speed, the hood should obscure the view of the terrain that moves at a very high angular velocity ("dead zone"). This applies to cars too. Failure to do so will adversely affect the performance of the human operator.
    By the way, on the MiG-23 pilots had problems with visibility when using NURS and AB. The dive angle, as a rule, was significantly higher than the optimum, therefore, on the MiG-27, the nose was cut off (sloping).
    On the other hand, the hood allows the pilot to navigate in space when flying at extremely low altitudes.
    In the 1940s and 50s, such issues were resolved without proper engineering and psychological support.
  9. Taoist
    Taoist 28 May 2016 16: 12
    Well, to be honest, I don’t quite understand why it was necessary to block such cities ... survey questions are of course important, but they are solved at lower cost and without sacrificing aerodynamics. The same BSh-MV ...
  10. Gray brother
    Gray brother 28 May 2016 16: 50
    I can imagine what it was like to sit on a hot engine.
  11. Disorder
    Disorder 28 May 2016 21: 59
    In the book "Aircraft Design Bureau named after SV Ilyushin", ed. G.V. Novozhilov considered the advantages of the IL-20, when attacking ground targets, over the IL-10, of the classic layout.
    Typically, IL-10 attack aircraft dive at a target at an angle of 30 degrees and fired from wing cannons and machine guns. In this position, they could drop to a height of about 50 m, after which, coming out of the dive and gaining height, attacked again. The time spent on building repeated approaches significantly reduced the effectiveness of the attack: the enemy hid or dispersed on the ground. A good overview allowed the IL-20 attack pilot to open aimed cannon fire from fuselage installations in horizontal flight while approaching the target, outside the range of its air defense. When attacking from a dive, for example, a mechanized convoy, the IL-20 attack aircraft could drop to a height of about 25 m and, after going into horizontal flight, hit the enemy with fire from fuselage cannons and bombs (Fig. 8.8).

    But during the construction of the prototype, the fuselage installation of guns was found to be impractical due to the low accuracy and limited use. On the prototype, 4 Sh-3 wing guns were installed, which, thanks to the design of the gun carriage, could be installed in two positions: either parallel to the axis of the aircraft, or at an angle of 22 degrees, as a result of which the advantages of the previous weapon arrangement were preserved.
    1. iouris
      iouris 29 May 2016 13: 16
      Interesting and very true.
      The attack aircraft must be able to hit the target from horizontal flight from an extremely low altitude and in just one run. Who makes the second call, as a rule, does not survive.
      Only here the idea could not be realized at that time. SPPU and the use of two types of TSA in one run appeared later and were implemented on the MiG-27.
      There are no data on combat applications of such regimes. Why?
  12. Dekabrev
    Dekabrev 29 May 2016 23: 36
    Now attack helicopters fly at much lower speeds and this does not bother anyone. Most likely this pepelats would have its own niche. It was not necessary only to throw at objects with unsuppressed air defense and without fighter cover. Although attack aircraft without fighter cover, probably only in the 41st were used.
  13. Black Colonel
    Black Colonel 31 May 2016 10: 58
    The rate of climb in the table is fabulous - 375 m / s. Apparently, still 375 m / min.