UNITED24 - Make a charitable donation in support of Ukraine!

Military


ER-2 / DB-240 - long-range bomber

As a prisoner Roberto Bartini participated in the alteration of the passenger aircraft "Steel-7" into a long-range bomber SB-240. He advised his former associates who in secret came to the prison at night. Despite this abuse, Roberto Bartini worked on the result. After a few months of such work, the Soviet Air Force received a high-speed long-range bomber unique in its combat capabilities, which became known as ER-2.

Apart from the external similarity of the DB-240 and "Stal-7" gull wing, the bomber became a completely different machine. First of all, it turned into an all-metal monoplane with twin-tail, versus the single tail on the "Steel-7". Thin-walled steel structures left no trace, everything was subordinated to technological processes mastered at serial aircraft plants. The new fuselage had two cabins for the crew and a bombardier. The advanced technology of manufacturing of a wing with use of the pressed and stamped profiles was applied. Virtually completely abandoned the welded farms, which allowed to significantly reduce the labor intensity of manufacturing the aircraft. So from the "Steel-7" there was only one, but a very important idea - the scheme.

This was a curious case in the history of aircraft: the plane does not give the name of its creator, and one of the engineers and the Party Secretary General Design Bureau V.G.Ermolaeva, nominally headed the team after the arrest of Bartini. SB-240 became the EF-2. Bartini's "right hand" was a talented engineer VG Ermolaev. He officially headed the development of the long-range bomber DB-240, the future Er-2, at the plant number 240.

Vladimir Grigorievich Ermolaev, a native of Mytishchi near Moscow, came to the GVF Research Institute in 1931 after graduating from the Faculty of Mechanics and Mathematics of the Moscow State University. M.V. Lomonosov. A well-trained engineer drew the attention of Bartini, who distinguished him among other specialists and began to prepare "for the chief designer."

It must be said that Ermolaev found himself fit for his "patron". A young man with a higher education was not only distinguished by his original thinking. In 1938 he graduated from the Moscow school Osoaviakhima, becoming a pilot. For an aircraft designer, this even today, during a continuous computerization, means a lot. Five years later, Vladimir Grigoryevich, a commission chaired by VKKokkinaki, the chief pilot of the OKB SV Ilyushin, appropriated the 4th class of the pilot of the transport aviation of the People's Commissariat of the aircraft industry.

ER-2 / SB-240Why did the Soviets need another long-range bomber? After all, there was already by that time DB-ZF - the future IL-4. True, its speed and range were slightly less than that of the DB-240, but that was enough to reach any industrial and military facilities in Germany from the territory of the Soviet Union. And why was it necessary to break the serial production of these aircraft at the plant No. 18 in Voronezh in order to launch the DB-240 series?

The history of the transition from "Steel-7" to DB-240 is still "dark" and it is not worth making any speculation. The memorandum of the head of Aeroflot Molokov, sent in October 1938 to the Council of People's Commissars of the USSR, said: "In a special version, the C-7 can be used as a high-speed bomber. The aircraft provides for the installation of a bow turret, with 2 SCAS with 750 rounds per each, for firing at the front hemisphere. The upper hemisphere is protected by an upper shielded turret installation with 2 SCAS with 750 rounds each. The shelling of the lower hemisphere is provided by a dagger installation in the middle of the fuselage with one SHKAS with 1000 cartridges.

In the spring of 1938, Z.B.Tsentsiper and his collaborators MVOrlov and N.P. Shebanov turned to KE Voroshilov with a proposal to re-create "Steel-7" into a distant bomber. Tsenziper for a long time did not work as chief designer, because he was "unreliable" and was punished shortly after Bartini's arrest. In 1939, Ermolaeva was appointed chief designer of the OKB plant No. 89 named after. Holtzman. A year later, this enterprise, which became the pilot base of the Yermolaev OKB, was transferred to the NCPAP by the decision of the Defense Committee, appropriating it No. 240. The plant's director was first MP Ozimkov and then VG Ermolaev.

The aircraft DB-240 was built in accordance with the resolution of the Defense Committee of July 29, 1939. The task was to create a long-range bomber with engines of liquid cooling M-106 with an estimated capacity of 1000 horsepower at an altitude of 6000 meters. The maximum speed was set at least 500 kilometers per hour. At an altitude of 4000 meters, the aircraft had to climb for 16 minutes and have a practical ceiling of 11,000 meters, with a range of up to 5000 kilometers. Three SHKAS machine guns were offered as defensive weapons, but machine guns ULTRASHKAS (USh) or 20mm guns on the MV-3 installation were not excluded. The experimental car was to be handed over on April 1, 1940 to state tests at the Air Force Research Institute. Tempting characteristics, but they were not destined to come true. First of all, the engines failed, and did not leave the factory walls.

In August 1939 the prototype of the bomber was defended. After a little over six months, the first experimental machine was rolled out of the gates of the assembly shop of the pilot plant. M-106 engines did not appear, and the first flight, as well as factory tests of the aircraft, was performed by NP Shebanov with less powerful M-105 engines. Despite this departure from the requirements set forth in the government's decree, the first results of the factory tests aroused rave reviews.

According to the flight crew, the control of the aircraft was simple, there was good stability and excellent visibility from the cabins. The technicians emphasized that in operation it was simple and convenient. In September 1940, the DB-240 was presented for state tests at the Air Force Research Institute. Leading by the machine appointed engineer Fingerov, pilots LP Dudkin and MA Nyuhtikov, navigators NP Tsvetkov and S.Z. Akopyan. The plane was flown by Stefanovsky, Malyshev, NI Shaurov, PI Nikitin and ID Sokolov.

The close acquaintance with the plane was impressive. The defensive armament consisted of a large-caliber BS machine gun with 200 ammunition ammunition on the TAT-BT upper turret removed in cruising flight in the fuselage and two 7.62mm SCASs on the nose "NU" and the hatch "LU" units with an ammunition of 1000 cartridges per barrel. The bomb load reached up to four tons. At the same time, up to two tons of bombs, including two FAB-500 bombs, were freely deployed in the cargo compartment, and there are still as many under the wing, including two FAB-1000s, the largest at that time domestic bombs. The gas tanks, which accommodated 6,300 liters, provided a range of 4,100 kilometers with takeoff with reloading weight. At the maximum speed of 455 kilometers per hour, obtained at factory tests, the aircraft yielded only to front-line bombers.

But it soon became clear that the fuel tanks on the machine are not protected by a protector, which means that in case of their firing the probability of a fire was great enough. And even with the most favorable outcome, the leakage of fuel left little chance for the task. The wheels did not match the weight of the car. There was no heating of the crew cabins and anti-icing devices of the wing socks and propeller blades.

Nevertheless, the four-man crew with many characteristics proved to be no worse than the foreign long-range bombers of those years, which were in service with Germany, Great Britain and the United States of America. The presence of spaced carpets, heavy machine gun and two rifles in the rear cabin provided for the defense of the aircraft in the rear hemisphere better than on the high-speed bomber SB and long-range DB-3. The aircraft had good track, but insufficient transverse stability, expressed in swinging from wing to wing. Longitudinally, the aircraft became unstable on the climbing regimes with the engines operating at maximum power and centering more than 28.5 percent of the average aerodynamic chord, in horizontal flight with centerlines greater than 30 percent, and in planning more than 34 percent.

In 1940, without waiting for the end of the state tests, the aviation plant No. 18 named after K.E. Voroshilov, who was in Voronezh, was issued an order for 70 DL-240 aircraft with M-105 engines. In accordance with the decree of the People's Commissariat of the aviation industry of December 9, 1940, the DB-240 was renamed into Er-2 and the following year the bombers began to leave the assembly shop. In April, the first seven aircraft were produced, in May - ten. In July, the production of bombers ended with the release of the 71st machine. Elimination of defects and taking into account the customer's remarks on the serial ER-2 resulted in their insignificant difference from the prototype. In particular, the exhaust pipes of the engines and the installation of the radio communication station antenna have been changed, the hatch in the cockpit of the navigator has been expanded. Apparently, already during the war the turret BT machine gun was replaced by ShKAS, and the crew was reduced to three people. It was necessary to eliminate the pressure drop of gasoline, which caused interruptions in the work of motors due to the suction of air into the fuel system from empty wing tanks and chassis defects. There were other improvements.

Weakened defensive weapons quickly manifested itself, and soon it was strengthened, returning to the original scheme. The flight characteristics of the production aircraft remained practically unchanged. The exception was the maximum speed, which dropped to 430 kilometers per hour due to the non-retractable upper rifle unit.

At the beginning of the war the Nazi leadershhip assured Germans that no stone will shudder in Berlin from enemy bombings, because, they say, Soviet aircraft were destroyed. But the stones did tremble in German capital - in the first months of the war Berlin was bombed by Ilyushin DB-3F, and then - more distant and speed Bartinievskie SB-240. These bombers flew from Moscow itself and back, without intermediate "hop aerodromes" and without refueling. However, the only flew a short time. The front line moved away to the east too fast.

During the two and a half years of the war, the main objectives of the Era-2 747th Regiment were railway junctions, in particular, Vyazma, Bryansk, Sukhinichi, Smolensk, Volovo, and echelons of the enemy were bombed on the trains. Airfields, such as, for example, Sescha, artillery positions in the Rzhev area were exposed. The last six Yer-2 aircraft were operated in the 747th Air Regiment until the end of 1943.

At the end of 1944, an attempt was made to improve the flight characteristics of the aircraft by installing the accelerated engine ACh-30BF on ER-2 No. 7023901. Tests carried out by the crew of the pilot Alexei Alexeyev showed a significant improvement in its takeoff properties with both normal and overload weight. However, the insufficient reliability of the power plant did not allow launching this version of the aircraft into mass production. Despite all efforts, the enterprises of the People's Commissariat of the aviation industry could not cope with the task set and, on the basis of the government decree of February 26, 1946, Er-2 was withdrawn from production, and then from the armament. By this time, there were 94 aircraft at the factory airfield, ready to be shipped to the customer, and in the assembly shop - 49 aircraft.

Air Marshal A.E.Golovanov said that the best Soviet long-range bomber at the beginning of the war was the Bartinievsky SB-240, and he was very sorry that these machines were small in number - only 300 pieces. And they quickly disappeared, ruined by uninvited improvements.

In May 1945, the General Directorate of the Civil Air Fleet considered the possibility of using combat aircraft to transport passengers and small civilian cargo. Did not ignore the bomber Er-2. According to experts of the Civil Air Fleet, the bomber, having a relatively small volume (11 cubic meters), allowed to transport only up to 2,200 kilograms of commercial load. But this disadvantage was compensated by the high cruising speed and range of flight, which, in combination with cheap diesel fuel, made the E 2 economically efficient in operation. However, there were no suitable aerodromes for the ER-2, which needed long runways, in civil aviation. Insufficient was the resource of the engines. Proceeding from this, the leadership of the GVF refused Yer-2.

The GVF also refused the civil Yer-20N, which allowed transporting up to nine passengers and a steward (commercial load of 1,000 kilograms), since the economy of this car left much to be desired. In addition, the flight on one engine was possible only with a weight of not more than 14 tons and with the presence of flying vanes that did not exist. As a transport plane, the Yer-2 lost noticeably to the Li-2, not to mention the Lend-Lizovsky C-47. As a result, almost all of the EP-2 was sent to scrap metal. Only a few aircraft used for flight testing of various products, in particular, when fine-tuning the pulsating air-jet engines for VC Chelomey air-to-air missiles.

By the spring of 1946, the Air Force had 233 Yer-2 aircraft, which, in accordance with the decision of the Council of Ministers of the USSR, were written off and disposed of on March 22 of the same year. Thus, the biography of an airplane designed for passengers turned into a bomber diver, but not in demand by either military or civilian agencies, was completed.

ER-2 / SB-240 ER-2 / SB-240

Stal-7 ER-2 / SB-240





NEWSLETTER
Join the GlobalSecurity.org mailing list



 
Page last modified: 07-09-2018 07:17:56 ZULU