The Kuznetsov NK-12 is a Sovietturboprop engine of the 1950s, designed by the Kuznetsov design bureau. The NK-12 drives two large four-bladed contra-rotating propellers, 5.6 m (18 ft) diameter (NK-12MA), and 6.2 m (20 ft) 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 6,000 shp (4,500 kW), weighing 3,000 kg (6,600 lb). The effort continued with a 5,000 shp (3,700 kW), weighing 1,700 kg (3,700 lb), completed by 1947. Evolution to the TV-12 12,000 shp (8,900 kW) 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 15,000 shp (11,000 kW) and 5,000 lbf (22 kN) jet thrust, ran 3,100 hours before being cancelled in 1957.[1][2] The NK-12 powers the Tupolev Tu-95bomber and its derivatives such as the Tu-142maritime patrol aircraft and the Tupolev Tu-114airliner (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.[3]
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[6]
^Connors, J. (2010). The engines of Pratt & Whitney : a technical history. American Institute of Aeronautics and Astronautics. p. 294. ISBN978-1-60086-711-8.
^Mulready, Dick (2001). Advanced engine development at Pratt & Whitney : the inside story of eight special projects, 1946-1971. Society of Automotive Engineers. p. 20. ISBN9780768006643.