Airplane SZ-2 (BB-1) on trials in Evpatoria at April 1938.

In the mid-30s in the Air Force, the tasks of the close, or as they called it then, light bomber were performed by the P-5 and P-Z multipurpose biplanes. In 1937, the production of a new, faster bomber R-10 began. Despite a significant improvement in flight characteristics, its capabilities still did not fully meet the requirements for a short-range bomber, reconnaissance aircraft and attack aircraft. Therefore, back in 1936, when the prototype R-10 was still being tested, a competition program was announced, which had the code name "Ivanov" (emphasis on "a"), to create a new promising single-engine multipurpose aircraft. The design bureaus of A.N. Tupolev, N.N. Polikarpova, I. G. Neman, D.P. Grigorovich, initially assuming joint, collective work. However, the "collective farm" did not work out and the best aircraft built according to this program turned out to be a two-seater aircraft developed at the Design Bureau of A.N. Tupolev's in brigade P.O. Sukhoi - ANT-51 (the aircraft was built by order No. 351 and by tradition was sometimes called TsAGI ANT-51).

August 25, 1937 chief pilot M.M. Gromov, who had just returned from a flight to San Francisco across the North Pole, lifted into the air the first copy of this machine, which had another name SZ-1 - "Stalin's task". Apparently the initiator of the competition was I.V. Stalin. The slogan "Ivanov" corresponded to the telegraphic address of the secretary general. During 1937-1938, the plane was tested, after which the engine exhausted its resource.

In December 1937, a second copy of SZ-2 was built with the same M-62 engine. Unlike the first aircraft, the bomb load was limited to 200-400 kg. During the tests, the military changed the main purpose of the aircraft and turning it into a close reconnaissance aircraft (attack aircraft).

By design, the SZ-2 was a free-carrying all-metal monoplane with retractable landing gear and an M-62 air-cooled motor (Russified "Wright"), created under the leadership of A.D. Shvetsova. An important decision of P.O. Sukhoi rejected the M-34 liquid-cooled engine and decided to immediately build an aircraft with dual control. On his initiative, in the frame of the machine, pressed duralumin profiles of the open type, recently mastered by our industry, were used as the main elements. The design solutions incorporated in the aircraft made it possible to use aggregate assembly, in-line assembly method with access to the conveyor, within a wide range. The test pilots considered the aircraft a model in terms of thoughtfulness, flight data, visibility and control characteristics.

At the end of state tests on March 26, 1938. The "understudy" was sent to the plant to replace the out-of-date engine, and after a three-month break, one of the first flights ended in disaster - on August 3, 1938, due to engine failure, the plane crashed along with the crew.

The construction of the third "Ivanov" SZ-3 (by order No. 452) was completed in September 1938. The design of the machine was similar to the previous two prototypes, the M-62 engine was replaced with a more powerful one and high-altitude M-87. The capacity of the gas tanks was reduced from 1030 to 700 liters, and the ammunition load of the wing machine guns was increased to 850 rounds each.

The aircraft "Ivanov" got to the state tests at the Air Force Research Institute with a cover letter, which said that it "is an extremely valuable object for the Red Army Air Force, must complete flight tests as soon as possible. The performed flights of the development and verification procedure show that the aircraft, both from the point of view of reliability and from the point of view of the communication of the control bodies, can perform flights according to the normal program ... ”. Filin recommended that the car be adopted by our aviation as a light bomber, with the possibility of using it as an attack aircraft and a close reconnaissance aircraft. Filin asked the People's Commissariat of the Aviation Industry to build by November 1, 1939, a military series of ten "Ivanovs", which would differ from the experimental one in a mixed design (wooden fuselage and metal wings).

It was planned that the aircraft would be mass-produced either with the M-88 engine (which was later to replace the capricious M-87), or with the M-63TK. In both cases, the maximum speed approached the 500 km/h mark desired by the leadership of the aviation industry,

But the resolutions adopted then were not destined to be realized for a long time. Numerous breakdowns of various engines (M-87, M-87A and M-87B) in 1938 - 1939. on "Ivanov" and other machines only accidentally did not lead to serious flight accidents, but caused long downtime. Not long before the events described here "for a wrecking delay in the introduction of M-87 engines" the director of the plant No. 29 P.I.Baranov S.A. Aleksandrov and some other prominent specialists was arested. The same fate befell the chief designer of the plant A.S. Nazarov. All of them completed an internship in France at the factories of the "Gnome-Rhone" company, managed to gain considerable experience, and their loss was very tangible for the business.

Since 1940, Ivanov with the M-88 engine began to be mass-produced under the designation BB-1 (close-range bomber), and soon it was given the name Su-2. The main tactical purposes of the aircraft were considered: reconnaissance aircraft, close-range bomber, attack aircraft and escort aircraft. Compared to the R-10, the Su-2 had stronger small arms (six machine guns against three) and much better speed qualities. The serial ones differed from the prototypes only in the design of the fuselage, which instead of metal became wood.

Photo	Description
	Drawing Su-2 with M-62 engine
	Airplane SZ-2 on trials in Evpatoria
	M-87A engined "Ivanov" at airfield. Flaps are turned down.

Bibliography

• "The history of designs of planes in USSR 1938-1950" /Vadim Shavrov/
• "Planes of Stalin falcons" /Konstantin Kosminkov and Dmitriy Grinyuk/
• "Attack aircrafts of Red Army" /Vladimir Perov Oleg Rastrenin/
• "Attack aircrafts Su-2. " /Dmitriy Khazanov, Nikolay Gordyukov/