Kuznetsov NK-12



The Kuznetsov NK-12 is a Soviet turboprop engine of the 1950s, designed by the Kuznetsov design bureau. The NK-12 drives two large four-bladed contra-rotating propellers, 5.6 m diameter (NK-12MA), and 6.2 m diameter (NK-12MV). It is the most powerful turboprop engine to enter service.

Design and development
The design that eventually became the NK-12 turboprop was developed after World War II by a team of Soviet 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 was designed to develop 6000 shp, weighing 3000 kg. The effort continued with a 5000 shp, weighing 1700 kg, completed by 1947. Evolution to the TV-12 12000 shp engine required extensive use of new Soviet-developed alloys and was completed in 1951.

The NK-12 is the most powerful turboprop engine to enter service, ahead of the Europrop TP400 (in 2005). Another engine of similar size, the Pratt & Whitney T57 with 15000 shp and 5000 lbf jet thrust, ran 3,100 hours before being cancelled in 1957. The NK-12 powers the Tupolev Tu-95 bomber and its derivatives such as the Tu-142 maritime patrol aircraft and the Tupolev Tu-114 airliner (with NK-12MV), which still holds the title of the world's fastest propeller-driven aircraft despite being retired from service in 1991. 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 pressure ratios between 9:1 and 13:1 depending on altitude, with variable inlet guide vanes and blow-off valves for engine operability. 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.

Variants
Data from Alexandrov


 * NK-12:9300 kW, initial development model, used on the Tupolev Tu-95 and Tupolev Tu-116
 * NK-12M:8950 kW, used on the Tupolev Tu-114
 * NK-12MV:11033 kW, 5.6 m AV-60 propellers, used on the Tupolev Tu-95, Tupolev Tu-126, and Tupolev Tu-142
 * NK-12MA:11186 kW, 6.2 m AV-90 propellers, used on the Antonov An-22
 * NK-12MK:11033 kW, 5.6 m propellers, built with corrosion-resistant materials, used on the A-90 Orlyonok
 * NK-12MP:11033 kW, modernized version used on the Tupolev Tu-95MS and Tupolev Tu-142M
 * NK-12MPM: Upgraded version of the NK-12MP that develops more power, produces half the vibration and is paired with the Aerosila AV-60T propeller; replaces the NK-12MP engine and AV-60K propeller on the Tupolev Tu-95MS

Applications

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