The Shvetsov ASh-73 was an 18-cylinder, air-cooled, radial

aircraft engine An aircraft engine, often referred to as an aero engine, is the power component of an aircraft propulsion system. Aircraft using power components are referred to as powered flight. Most aircraft engines are either piston engines or gas turbin ...

produced between 1947 and 1957 in the

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. It was primarily used as the powerplant for the Tupolev Tu-4

heavy bomber Heavy bombers are bomber Fixed-wing aircraft, aircraft capable of delivering the largest payload of air-to-ground weaponry (usually Aerial bomb, bombs) and longest range (aeronautics), range (takeoff to landing) of their era. Archetypal heavy ...

, an unlicensed, reverse engineered copy of the American

Boeing B-29 Superfortress The Boeing B-29 Superfortress is a retired American four-engined propeller-driven heavy bomber, designed by Boeing and flown primarily by the United States during World War II and the Korean War. Named in allusion to its predecessor, the Bo ...

Design and development

The Shvetsov ASh-73 originated in 1938 from a specification for an 18-cylinder, twin-row, development of the Shvetsov M-25, a license-built 9-cylinder, air-cooled, radial Wright R-1820-F3 Cyclone engine. Development continued through a series of less than successful engines, before culminating in the ASh-73. The ASh-73 was not a reverse-engineered copy of the Wright R-3350 Duplex-Cyclone, itself starting its development in 1937: "There was no need to copy the Wright R-3350-23A; the engine that was put into production was the indigenous ASh-73TK - a further development of the M-71 and M-72, which differed in being fitted with twin TK-19 turbosuperchargers (TK = ''toorbokompressor'')."Gordon and Rigmant, p. 21 rather the ASh-73 was the product of a similar specification. Since the earlier M-25 engines were a licensed copy of the Wright R-1820, there were similarities and some parts were interchangeable between the Duplex Cyclone and the ASh-73 powerplants. The two engines evolved from a common ancestor and to a similar requirement. "In the late 1930s and the early 1940s OKB-19 evolved two 18-cylinder two-row radials — the 2,000-hp M-71 and the 2,250-hp M-72 — which were similar in their design features and production techniques to the Wright Duplex Cyclone engines powering the B-29." The progenitor for the ASh-73 was the M-70. It was tested in late 1938 and was a failure because of cracks in the master

connecting rod A connecting rod, also called a 'con rod', is the part of a reciprocating engine, piston engine which connects the piston to the crankshaft. Together with the crank (mechanism), crank, the connecting rod converts the reciprocating motion of the p ...

and the geared

centrifugal supercharger A centrifugal supercharger is a specialized type of supercharger that makes use of centrifugal force in order to increase intake pressures and power. An increase in combustion intake air pressure allows the engine to burn more fuel, which results i ...

's impeller. The exhaust valves also burnt through. The M-71 of 1939 was the successor to the M-70 and it too was not a success. It used some components from the M-62 engine, but its development was slowed by the German attack on the Soviet Union in 1941. It passed its State acceptance tests in the autumn of 1942, but was not placed into production as there was not any production capacity available, although it was tested on a number of different prototypes during the war. The M-72 of early 1945 was a boosted version of the M-71 and was superseded by the ASh-73 before production could get underway.Kotelnikov, pp. 129–30 The first prototypes of the ASh-73 were built in 1945 and by the end of 1946 testing had completed successfully. The first models to enter production in 1947 lacked turbo-superchargers. They weighed and had during take-off. The ASh-73TK had two TK-19

turbocharger In an internal combustion engine, a turbocharger (also known as a turbo or a turbosupercharger) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake air, forcing more air into th ...

s and an

intercooler An intercooler is a heat exchanger used to cool a gas after compression. Often found in turbocharged engines, intercoolers are also used in air compressors, air conditioners, refrigeration and gas turbines. Internal combustion engines Mo ...

fitted which were direct copies of the units used on the R-3350. The engine was upgraded over the course of its production. On the fourth series of engines the

crankshaft A crankshaft is a mechanical component used in a reciprocating engine, piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating Shaft (mechanical engineering), shaft containing one or more crankpins, ...

nose was changed, the articulated connecting rods were strengthened and the accessory drive was changed. The middle part of the crankcase and the pistons were strengthened and the ignition was improved in the fifth series. In the sixth series the master connecting rod and the crankshaft cheeks were strengthened, the pistons were lightened and shortened. For the seventh series exhaust valves with floating seats were introduced and the reduction gearing was improved. The displacement of the ASh-73 ended up being slightly larger than the Wright Duplex-Cyclone radials of the B-29 - while having the same cylinder count and basic layout, the ASh-73 possessed a 58.122 liter (3,546.8 in3) displacement figure, some 6% larger than its American contemporary's 54.86 L (3,347.9 in3) displacement figure. A boosted version was developed as the ASh-82TKF that had a rating of . It was bench tested, but not put into production. A further development in 1949 was the ASh-73TKFN with

fuel injection Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of a fuel injector. This article focuses on fuel injection in reciprocating piston and Wankel rotary engines. All c ...

that boosted power to , but it too was not built. Another 1949 project was an ASh-73TK with a power-recovery turbine to create a turbo-compound engine, but no other information is known.Kay, p. 130 Factory No. 19 began preparation to build the ASh-73 in 1946, but production did not begin until the next year. Production continued there until 1953. Factory No. 36 in Rybinsk also produced it until 1957. A total of 14,310 ASh-73s were built. A number of these were exported to the

People's Republic of China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

during the 1950s as spare parts for their Tu-4s.

Applications

* Beriev Be-6 * Ilyushin Il-18 (1946) *

Petlyakov Pe-8 The Petlyakov Pe-8 () was a Soviet heavy bomber designed before World War II, and the only four-engine bomber the USSR built during the war. Produced in limited numbers, it was used to bomb Berlin in August 1941. It was also used for so-called " ...

(in service with

Aeroflot PJSC AeroflotRussian Airlines (, ), commonly known as Aeroflot ( or ; , , ), is the flag carrier and the largest airline of Russia. Aeroflot is headquartered in the Central Administrative Okrug, Moscow, with its hub being Sheremetyevo Interna ...

, post-war) * Tupolev Tu-4 * Tupolev Tu-70 * Tupolev Tu-75 * Tupolev Tu-80

Specifications (Shvetsov ASh-73TK)

References

Notes

Bibliography