Government Designation: 17D61. Designer: Melnikov. Application: Ikar stage 4 for Soyuz-Ikar. Used on stages: Ikar. Used on launch vehicles: Soyuz 11A511U / Ikar. Propellants: N2O4/UDMH Thrust(vac): 300 kgf. Thrust(vac): 2.94 kN. Isp: 326 sec. Burn time: 600 sec. Mass Engine: 820 kg. Diameter: 2.7 m. Length: 2.6 m. Chambers: 1 + 4 + 4 + 8. Chamber Pressure: 9.00 bar. Country: Russia. Status: In Production. References: 69 , 345 , 346 . Derived from propulsion module of Yantar spysat, over 30 flights to 1998. Ikar upper stage upgrades the Soyuz LV, replaces Block L; increased versatility due to capability for 50 restarts. Engine thrusts: 1 x 2943 N + 4 x 110 N + 4 x 52 N + 8 x 5.88 N.