Manufacturer Name: NK-43. Government Designation: 11D112. Designer: Kuznetsov. Developed in: 1969-74. Application: N-1F stage 2 (block B). Used on stages: Kistler Stage 2, N1F Block B. Used on launch vehicles: Kistler, N1F, N1F Sr, N1F-L3M. Propellants: Lox/Kerosene Thrust(vac): 179,000 kgf. Thrust(vac): 1,755.00 kN. Isp: 346 sec. Isp (sea level): 246 sec. Burn time: 600 sec. Mass Engine: 1,396 kg. Diameter: 2.5 m. Chambers: 1. Chamber Pressure: 145.70 bar. Area Ratio: 70.00. Oxidizer to Fuel Ratio: 2.80. Country: Russia. Status: In Production. References: 351 . Version of NK-33 with higher expansion ratio nozzle for operation at altitude. After initial failures of the N-1 the company developed modified versions of engines for all four stages, which had multiple ignition capability and increased operational lifetime. Never flown, they were mothballed and selected by Kistler 20 years later for the second stage of their commercial launch vehicle.