NK-43

Kuznetsov LOx/Kerosene rocket engine. N-1F stage 2 (Block B), Kistler stage 2. Development completed 1975. Modified version of original engine with multiple ignition capability. Never flown and mothballed after the cancellation of the N1. Resurrected for Kistler.

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. Mothballed on cancellation of N1 in 1974. Selected by Kistler 20 years later for the second stage of their commercial launch vehicle, which was cancelled in turn before any flights were made.

Thrust (sl): 1,247.800 kN (280,517 lbf). Thrust (sl): 127,237 kgf. Engine: 1,396 kg (3,077 lb). Chamber Pressure: 145.70 bar. Area Ratio: 70. Thrust to Weight Ratio: 128.22. Oxidizer to Fuel Ratio: 2.8.