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The Kuznetsov NK-12 is a Soviet turboprop engine of the 1950s, designed by the Kuznetsov design bureau. It drives large eight-bladed (four per propeller) contra-rotating propellers 5.6 m (18 ft; 45 in) in diameter, and 6.2 m (20 ft; 4.1 in) in the NK-12MA and NK-12MV. It is the most powerful turboprop engine ever built.
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Design and development
The design that eventually became the NK-12 turboprop was developed after World War II by a team of Russian scientists and deported German engineers under Ferdinand Brandner, which had worked for Junkers previously; the design bureau was headed by chief engineer Kuznetsov. Thus, NK-12 design evolved from late war German turboprop studies. This started with the post-war development of the wartime Jumo 022 turboprop design that developed 6000 eshp in a 3000 kg engine. The effort continued with a 5000 ehp engine that weighed in at 1700 kg, completed by 1947. The evolution to the TV-12 12000 Ehp engine required extensive use of new Soviet-developed alloys and was completed in 1951.
The NK-12M developed 8,948 kW (12,000 ehp), uprated in the NK-12MV to 11,033 kW (14,795 ehp) and reaching 11,185 kW (15,000 ehp) in the NK-12MA. The NK-12 remains the most powerful turboprop engine ever built. Only recently the Progress D-27 and Europrop TP400 came somewhat close. It powered the Tupolev Tu-95 bomber and its descendants like the Tu-142 maritime patrol aircraft and the Tupolev Tu-114 airliner (with NK-12MV), which is still the world's fastest propeller-driven aircraft (despite the fact that all Tu-114s have been retired). It also powered the Antonov An-22 Antei (with NK-12MA), the world's largest aircraft at the time, and several types of amphibious assault craft, such as the A-90 Orlyonok "Ekranoplan" and the Zubr class LCAC.
The engine has a 14-stage axial-flow compressor, producing compression ratios between 9:1 to 13:1 depending on altitude, also controlled by variable inlet guide vanes and blow-off valves. The combustion system used is a cannular-type: each flame tube is centrally mounted on a down-stream injector that ends in an annular secondary region. The contra-rotating propellers and compressor are driven by the 5-stage axial turbine. Mass flow is 65 kg (143 lb) per second.