|NK-12M Turboprop engine on a Tu-95 at RIAT Fairford 1993|
|National origin||Soviet Union|
|Manufacturer||Kuznetsov Design Bureau|
|Major applications||Antonov An-22
The Kuznetsov NK-12 is a Soviet turboprop engine of the 1950s, designed by the Kuznetsov design bureau. It drives huge eight-bladed (four per propeller) contra-rotating propellers 5.6 m (18 ft 4.5in) in diameter (6.2 m (20 ft 4.1in) in the NK-12MA and NK-12MV). It is the most powerful turboprop engine ever built.
Design and development
The design that eventually became the NK 12 turboprop was developed after World War II by a team of deported German engineers under Ferdinand Brandner, which had worked for Junkers previously. Thus, the 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. 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) /sec.
- Maximum power output: 11,033 kW (14,795 ehp), for NK-12MV
- Overall pressure ratio: 9.5
- Turbine inlet temperature: 1250K
- Specific fuel consumption: 0.360 lb/shp-hr  0.219 kg/kW-hr for NK-12MA and NK-12MV
- Power-to-weight ratio: 3.7 kW/kg (2.3 hp/lb), for NK-12MV
- Related lists
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