Shvetsov ASh - 73 The Shvetsov ASh - 73 was an 18 - cylinder , air - cooled , radial aircraft engine produced between 1947 and 1957 in the Soviet Union . It was primarily used as the powerplant for the Tupolev Tu - 4 heavy bomber , a copy of the American Boeing B - 29 Superfortress . Design and development . The Shvetsov ASh - 73 originated in 1938 from a specification for a 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 . Contrary to popular belief the ASh - 73 wasn ' t a reverse engineered copy of the Wright R - 3350 Duplex Cyclone : " 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 " ) . " 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 and the geared centrifugal supercharger ' 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 The M - 72 of early 1945 was a boosted version of the M - 71 and was superseded by the ASh - 73 before production could get underway . 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 turbochargers and an intercooler 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 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 . 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 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 . 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 during the 1950s as spare parts for their Tu - 4s .