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Soviet Aircraft Engines

ACh	A.Charomski
AI	A.Ivchenko
AL	Arkhip Lulka
AM	Alexander Mikulin
ASh	A.Shvetsov
M	many designers
NK	N.Kuznetsov
PS	P.Soloviev
R	Tumanski
VD	V.Dobrynin
VK	V.Ya.Klimov

A particular difficulty for the Czar's aircraft industry was the production of engines. A lack of good steels resulted in a weak metallurgical base and there were other difficulties in the production of magnetos, spark plugs, and various instruments and devices. During the Great War only ten to fifteen percent of the required aircraft engines were supplied by Russian plants. The Soviet state received a poor inheritance in aviation: some hundreds of old and worn-out airplanes, mostly of foreign-make and obsolete plants and worshops producing aircraft and engines, partly based on domestic labor. The aircraft industry had to be built from the beginning. From the first days of Soviet power Lenin concentrated on the creation of a Red air fleet, and according to his instructions, TsAGI was founded in 1918 under the direction of Professor N. E.Joukowski. The building of the country's aviation became a national task.

The development of the Soviet aircraft engine industry in the 20s. Initially, it was aimed at mastering the mass production of foreign samples of ever higher power using domestic materials and technologies and introducing various improvements into their design. By 1926, at the plant "Motor" A.D Shvetsov designed the first Soviet aircraft engine, the PD-M-11 with a capacity of 80.9 kW, was used for several decades in light-engine aircraft.

In 1939 the Defense Committee of the Council of People's Commissars of the USSR adopted two extremely important resolutions. One concerned the building and reconstruction in 1939-41 of enterprises producing aircraft power plants and propellers. The second resolution dealt with the development of aircraft engine plants. Plans were made for building new plants and for the reconstruction of existing plants which should produce engines for combat aircraft. It was necessary at the beginning of 1941 to double the number of aircraft engine plants over that of 1939. To help engine construction, some enterprises were transferred from other branches to the aircraft industry, and production of aircraft engines was organized in some automobile plants.

A motor gives the plane life. At the beginning of the war, the Soviet Union had engines that were not inferior to the best foreign models. We owe this to their creators - designers, scientists and factory teams. Vladimir Yakovlevich Klimov was a talented engine designer. Taking at one time the basis of the water-cooling engine "Hispano-Suiza", Klimov achieved results that this company could not achieve. Arkady Dmitrievich Shvetsov designed air cooling engines that were used on fighters. The main consumer of the M-11 engine became Lavochkin aircraft in the war. The third designer of aircraft engines from this cohort is Alexander Alexandrovich Mikulin. Its AM-34 engines, then the AM-35, and just before the war, the AM-38 was installed on heavy bombers and Ilyushin attack aircraft. For long-range bomber aircraft, the M-88 engine of the design bureau of Evgeny Vasilievich Urmin was used.

It was obvious that the coming war would be a "war of engines", and victory would be on the side of those whose technology was on a higher level, where scientific and technical thinking was best. During the late thirties piston engine power was rapidly increased, together with a reduction in the specific weight of the engines. The power of series produced engines rose from 700 hp or 800 hp to 2000 hp and the specific weight dropped from 0.9 kg/hp to less than 0.5 kg/hp, i. e., almost by one half, At the same time considerable success was achieved in reducing the specific dimensions of the engines. All this contributed to increased speed, ceiling and range of Soviet aircraft.

In 1937, the famous aircraft designer S. Ilyushin began designing an armored ground-attack aircraft IL-2, and the aircraft was launched into mass production only in early 1941. The reason for the delay was that there was no motor suitable for this type of aircraft. In 1939, the design of a front-line dive bomber, which later received the name "103", then the Tu-2, began to be designed by the NKVD in a special technical bureau of the NKVD under the guidance of the well-known aircraft designer A.N. Tupolev. However, these tests were carried out only in August 1941, and their engine could not stand because of serious design flaws (destruction of the main connecting rod, bushings, supercharger gears and other defects).

The first experimental TB-7 test in 1937 was tested, that the large ceiling of the aircraft (8000-10000 meters), made it less vulnerable, and on the strength of the bombing weapons it was at the level of the world's best high-speed bombers of that time. Unfortunately, further tests of aircraft and the implementation of a large amount of finishing work showed that the industry can not eliminate the extremely serious defect of the engines - the oil pressure drop below the permissible limit at an altitude of more than 6,000 meters.

Four boosted AM-34F RNB engines retain a capacity of 4,800 horsepower to an altitude of 3,500-4,000 meters. The fifth M-100 engine (named ACN-2) was installed in the fairing of the fuselage, behind the pilot's back. It increased the altitude of the main to 8000 meters and was launched in flight as needed. Thanks to this, the multiton air ship with its maximum flight data at a ten-kilometer height exceeded all the best European fighters of that time.

In connection with this, it became obvious that there was no sense in continuing the work on the development of systems that would raise the aircraft's altitude to 8,000-10,000 meters (including the installation of significantly smaller and more compact turbochargers TK-1 on motors, instead of the heavy and bulky "compressor station" on board - ACN-2). As a result: the work on the creation of a power plant for a high-altitude aircraft TB-7, for which much effort, money and time was spent, did not yield a positive result.

The history of the Great Patirotic War was the "war of engines" - a competition of national technologies, expressed in the level of the developed capacities. After all, power is directly related to the speed of the aircraft and its armament (weapons, armor protection, ammunition): the more the engine power, the higher these characteristics. The surface layer of the main components determines the longevity of the engine, and the obtaining of the necessary surface layer is completely determined by the manufacturing technology used. The manufacturing tolerances guaranteeing the operability of the structure are the result of long-term operational development and exploitation and therefore constitute a true know-how.

At high altitudes air pressure goes down, and so there is less oxygen in a given amount of air, which means that engines do not burn as cleanly, and so lose power. Superchargers compress air before it is pumped into the engine cylinders so that there is enough oxygen for the engine to function well. It was also clear that one of the key elements of increasing the capacity of engines was an air supercharger that compensated for the decrease in air density with increasing altitude. During the Great Patriotic War, a number of powerful engines were serially produced by Vladimir Klimov, including the M-105, VK-105PF, VK-107, and VK-108, equipped with a two-speed air supercharger of original design.

In the United States, General Electric developed turbochargers for military aircraft, and in World War II, thousands were used on fighter aircraft and bombers, such as the B-17. As with the supercharger, the turbocharger increases the density of air entering the engine to create more power. The supercharger direct mechanical drive takes its power from the crankshaft, whereas the turbocharger draws power for the compressor from the engine's own exhaust gases that result from combustion. Superchargers can spin with speeds up to 50,000 RPM. The turbocharger is not connected to the engine and can spin much faster. The turbocharger is more efficient as it doesn't require engine power to spin it.

In 1935 an American GE turbocharger was installed on a M-5 powere R-1. This was the first use of a turbo-supercharger in the Soviet Union. The first American turbocharger was on a Liberty engine in 1918, 17 years earlier.

Particular attention should be paid to the works of Mikulin on turbochargers. Even before the war, together with specialists from CIAM, he took an active part in the development of the TK-3 turbocharger. In 1943, the factory #300 completed the refinement of this first Soviet turbocharger, which worked reliably for an established resource. Subsequently, in March 1944, the plant #300 began mass production of the TK-3 for high-altitude Myasishchev and Lavochkin aircraft.

In parallel with TK-3, Mikulin developed the turbo-compressor of his own design TK-300, then TK-300B, which were prototypes of the unique turbo-compressor AMTK-1. Mikulin began to design it at the end of 1943. In May 1944, the turbocharger AMTK-1 satisfactorily passed 100-hour tests on the stand. The creation of the AMTK-1 turbocharger of the original Soviet design entirely from domestic materials opened up great opportunities to create high-altitude aircraft for our Air Force at a fast pace.

The main characteristics of piston aircraft Motors A.A. Mikulina

Motor		M-34 ph	M-34 FRN	AM-35 A	AM-38	AM-38 F	AM-39	AM-42
Year		1934	1936	1940	1941	1943	1944	1944
Compression ratio		6.0	6.0	7.0	6.8	6.0	6.0	5.5
Engine weight, kg		743	735	830	860	880	971	996
Take-off mode	Power, HP	750	1200	1350	1600	1700	1800	2000
	Speed, rpm	1850	2000	2050	2150	2350	2350	2500
	Supercharged, MM Hg.	870	880	1240	1285	1360	1360	1565
Nominal terrestrial mode	Speed, rpm	1850	1850	2050	2050	2050	2050	2350
	Supercharged, MM Hg.	735	740	1040	1180	1200	1200	1335
	Power, HP	750	1050	1120	1500	1500	1630	1750
High-altitude mode	Height, M	3500	3050	6000	1650	750	5850	1600
	Power, HP	750	1050	1200	1500	1500	1500	1770
Nominal specific parameters	Liter Power, HP/L	14.71	22.5	24.0	32.15	32.15	38.6	37.5
	Avg. DVEF, kcm/cm2	7.17	10.96	10.54	14.11	14.11	14.87	14.36
	Specific weight, kg/hp	1.07	0.7	0.74	0.57	0.59	0.53	0.57
Reduction degree		0.732	0.732	0.902	0.732	0.732	0.732	0.60
All Motors "AM": Number of cylinders 12, diameter of cylinder 160 mm, stroke of piston 190 (196.8) mm, working volume 46.66 L

The main difficulties encountered by aircraft designers during the Second World War when creating new high-speed combat aircraft were associated with the impossibility of further increasing the power of their propeller group. The required power of a piston engine, necessary for obtaining the maximum flight speed, is approximately proportional to the cube of speed, which led to an increase in engine mass and, accordingly, to an unacceptable increase in the mass of the aircraft as a whole. The solution to this problem was found only with the advent of jet engines.

Work on the creation of gas turbine engines (GTE) of various schemes began in the twenties. In 1924, engineer Vladimir Bazarov (later he worked for Mikulin as a lead designer for promising developments) proposed an air-jet engine design in which air, entering the combustion chamber, was divided into two streams. Boris Stechkin was also engaged in developing the theory of a turbojet engine. After the outbreak of the war, these works in the USSR were actually mothballed, while in England and Germany, the rate of creation of aircraft turbojet engines significantly accelerated.

In 1945 the Soviets were in much the same position Whittle had been in 1930. The Soviets had industry manufacturing aircraft turbochargers or the materials and tooling required, and little knowledge of the aerodynamics involved. It turned out that the turbocharger blades on the American engine were made of heat-resistant alloys based on cobalt, which in the USSR simply did not exist in adequate amounts. After the Great Patriotic War, the Tu-4 utilised four Shvetsov ASh-73TK eighteen-cylinder turbocharged radial engines. The ASh-73TK had two first-stage TK-19 exhaust driven turbochargers.

Although the Soviets had some background in jet turbine design dating back to 1937, the work of its most experienced jet technician, Arkhip Lyulka, had been interrupted during the Great Patriotic War. After working on an unheralded rocket aircraft project, Lyulka returned in 1942 to jet turbine work. By the end of the war he was bench testing an experimental engine of 1,543 pounds thrust and had initiated work on a 2,866 pounds thrust engine intended for flight testing. It was apparent, however, that these engines were behind the world standard and would require extensive development while German engines were already available. The Commissariat plan would allow attention to be given to advanced engine design while native designed aircraft would be based on engines of foreign derivation.

In 1946 Soviet jet engine designers approached Stalin with a request to buy jet designs from Western sources to overcome design difficulties. Stalin is said to have replied: "What fool will sell us his secrets?" However, he gave his assent to the proposal, and Soviet scientists and designers travelled to the United Kingdom to meet Cripps and request the engines. To Stalin's amazement, Cripps and the Labour government were perfectly willing to provide technical information on the Rolls-Royce Nene centrifugal-flow jet engine designed by RAF officer Frank Whittle, along with discussions of a licence to manufacture Nene engines. The Nene engine was promptly reverse-engineered and produced in modified form as the Soviet Klimov VK-1 jet engine, later incorporated into the MiG-15 which flew in time to deploy in combat against UN forces in North Korea in 1950.

The strategy for post war development of jet fighters was based on the rapid achievement of superior jet engine capability. In the first post war decade, Soviet air defense was dominated by a concerted program to equip fighter forces with jet aircraft. A major commitment was made early in 1946 to focus on advanced jet engine development while using foreign technology to support intermediate aircraft development. The plan was in three stages:

1. The development of interim aircraft based on captured German engines. This stage resulted in the YAK-15 and MiG-9 aircraft which were first flown on April 24, 1947. These were produced in limited quantities—some 800 MiG-9’s and 265 YAK-15’s and 610 YAK-17’s (an improved version of the YAK-15).
2. The development of combat capabilities based on imported British technology, namely the Rolls Royce Nene and Derwent engines. This stage was to result in the YAK-23, the La-15, and the ubiquitous MiG-15. Altogether some 120 Lavochkin and 930 YAK-23 aircraft would be produced. Ultimately, approximately 12,500 MiG-15’s would be produced in four variants: a day interceptor, an improved performance day interceptor, a limited all-weather interceptor, and a reconnaissance attack version.
3. The development of advanced interceptors on the basis of native engine technology derived from the efforts of the Klimov, Lyulka, Mikhulin, and Zumansky engine design bureaus: Of the development efforts Klimov’s V K-1 engine was the first and was used to power the MiG-15 bis the improved day interceptor.

Key to the strategy was the purchase of British Rolls Royce centrifugal compressor engines—the Nene and the Derwent. In reacting to this strategy, Stalin is said to have remarked, “Just what kind of fool would sell his own secrets!” Nevertheless, the Russians had had considerable experience with the British unclassified lists during the war and were aware that licenses for production of these engines were being sold in a number of countries. The successful attempt to purchase these engines would proceed. It was not until 1951, with the development of the Mikhulin AM-5 small, efficient, axial-flow engine that a long-range, all-weather interceptor became technically convenient. Such an engine made practical an alternate aircraft configuration which would accommodate the large radome associated with Soviet air intercept radars of that era.

The rapid deveiopment of the construction of jet aircraft in the Soviet Union was due to the outstanding successes in producing jet engines. It should be pointed out that Soviet jet engines at that time did not have their equal in other countries, both regarding design and thrust. An early Soviet lead in jet engine technology was overcome in the early 1950s, and since then American technology moved ahead. Many American designs of the period moved to production status because of the demands imposed by the Korean War, and the challenge of surprisingly good Russian engines. The early 1950s saw the baginning of engines designed to sustain flight at speeds through Mach 2. During the early 1960s there was continued emphasis on the development of new materials and on improvements, in component performance and design.

The major statistically significant difference between the Soviet and the US engines of the 1960s and 1970s was in the value of the coefficients for turbine inlet temperature, implying, not implausibly, that US and Soviet designers were emphasizing different aspects of technology. The Soviets seem to have been concentrating more on the front of the engine, increasing thrust-per-pound of air flow and putting into production a transonic compressor before the United States, whereas the United States moved toward the back of the engine with high turbine inlet temperatures and the requisite advanced metallurgy.

The apparent difference between the technologies of the United States and the Soviet Union was also probably due in part to differences in military requirements. Soviet combat equipment generally was designed for a high-intensity conflict of short duration. Soviet units typically trained at lower levels than their Western counterparts. By the 1980s Soviet jet aircraft engines were good for only about 600 hours between major overhauls, compared to some 1,500 hours typical of Western units. Nor were they designed with fuel efficiency in mind.