Wright R-3350 vs Shvetsov ASh-73TK Comparison chart

    The American R-3550 and the Soviet ASh-73TK were both large, twin-row engines with nine cylinders in each row. While both engines had an identical bore size of 155.6 mm, the ASh-73TK had a longer stroke size of 169.9 mm and a larger displacement of 58.122 liters. In contrast, the R-3550 had a stroke size of 160.2 mm and a displacement of 54.86 liters.

    The ASh-73TK was developed from the initial ASH-73, which was a “cousin” of the Wright R-3350, having evolved independently from the Wright R-1820 Cyclone engine but using similar design elements. However, it was modified with the addition of twin TK-19 exhaust-driven two-speed superchargers and a single-speed geared centrifugal supercharger in order to improve high-altitude performance. The turbochargers, carburetors, and bearings of the ASh-73TK were copied from the R-3550.

    Due to its similarities to the R-3550, the ASh-73TK was chosen for use in Soviet copies of the B-29 (the Tu-4), allowing it to be fitted into the copies of B-29’s cowlings and nacelles.

    While ultimately reliable, the ASh-73TK did encounter some induction system fires during its early stages of use, similar to the issues faced by the R-3550.

    We can compare the parameters of both engines in the following table:

    Model R-3550ASh-73TK
    ManufacturerWright Aeronautical Division of the Curtiss-Wright CompanyOKB-19, later the Perm Motor Design Bureau
    Production run1941-19451947-1953
    Produced32,22114,310
    ApplicationsB-29, A-1, DC-7, P-2, Lockheed ConstellationTu-4, Be-6, Tu-75, Tu-80, and S-82(Not completed)
    Type18 cylinders, 2-row radial, air-cooled, geared drive, Supercharged, 4-cycle18-cylinder two-row star-shaped, air-cooled, geared, with one-stage single-speed monitoring station;
    SuperchargerG.E. Gear-driven, 2-speed supercharger, ratio 6.61:1 and 8.81:12 x TK-19 exhaust-driven turbo-chargers and a second supercharging stage, with PTsN single-speed centrifugal blowers driven by the engines.
    Bore6.125 in.155 mm6.125 in.155.6 mm
    Stroke6.3125 in.160 mm6.689 in169.9 mm
    Displacement3.347cuin54,9 lit3.546.8 cu in58.122 liters
    Compression Ratio6.85:16,85:16.9:16.9:1
    Diameter55.8 in.1417 mm54.13 in1375 mm
    Length55.8 in.1935 mm 90.16 in2290 mm
    Weight2670 lb.1211 kg2952 lb1339 kg
    Fuel consumption (cr)0.46 lb./h.p./hr.210 g/hp/hr0.69-0.74 lb/hp-hr315-335 g/hp-hr
    Rating (take off)2,200 h.p./2,800 r.p.m. at sea level2,400 hp
    Rating (normal)2,000 h.p./2,400 r.p.m./4,500 ft. (1 400 m)2,000 hp (2,400 rpm, 28,215-30,515 ft or 8,600-9,300 m)
    Military2,200hpr2,600rpm/25,000ft (for maximum of 5 minutes)2,200 hp (26,250-28,545 ft or 8,000-8,700m)

    Further reading

    Source

    • Tupolev Tu-4: The First Soviet Strategic Bomber by Yefim Gordon and Dmitriy Komissarov
    • Russian Piston Aero Engines: The Complete Story by Victor Kotelnikov
    • Boeing B-29 Superfortress: The Ultimate Look: From Drawing Board to VJ-Day by William Wolf

    Javier is the editor @ Nuclear Companion and loves to investigate and write about the cold war.

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