Kuznetsov NK-12

NK-12
NK-12M Turboprop engine on a Tu-95 at RIAT Fairford 1993
Type	Turboprop
National origin	Soviet Union
Manufacturer	Kuznetsov Design Bureau
Major applications	Antonov An-22 Tupolev Tu-95 Tupolev Tu-114

The exhaust ports of a NK-12 in an outboard nacelle on a TU-95

A pair of Kuznetsov NK-12MAs installed on an Antonov An-22

The Kuznetsov NK-12 is a Soviet turboprop engine of the 1950s, designed by the Kuznetsov design bureau. It drives two large four-bladed (eight blades per engine) contra-rotating propellers, 5.6 m (18 ft 4.5 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.

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, who had worked for Junkers previously; the design bureau was headed by chief engineer Nikolai D. Kuznetsov. Thus, the NK-12 design evolved from late-war German turboprop studies. This started with the postwar 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. The Progress D-27 and Europrop TP400 came close to this only recently. It powered the Tupolev Tu-95 bomber and its descendants such as 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".

The engine has a 14-stage axial-flow compressor, producing compression ratios between 9:1 and 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 downstream injector that ends in an annular secondary region. The contra-rotating propellers and compressor are driven by the five-stage axial turbine. Mass flow is 65 kg (143 lb) per second.

Applications

• A-90 Orlyonok
• Antonov An-22
• Tupolev Tu-95
• Tupolev Tu-126
• Tupolev Tu-142
• Tupolev Tu-114
• Tupolev Tu-116

Specifications

General characteristics

• Type: turboprop
• Length: 4.8 m
• Diameter: 1.2 m
• Dry weight: 2,900 kg (6393 lbs), for NK-12MV

Components

• Compressor: Axial flow, 14 stages
• Turbine: 5 stages

Performance

• Maximum power output: 11,033 kW (14,795 ehp), for NK-12MV
• Overall pressure ratio: 9.5
• Turbine inlet temperature: 1250 K
• 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

See also

Related lists

• List of aircraft engines

External links

• ciad.ssau.ru - Image
• airventure.de - Image, finnish museum