Encyclopedia Astronautica

Credit: © Mark Wade
Tripropellant motors use high-density kerosene for the boost phase, then low-density, high-performance liquid hydrogen for the later stages of ascent. However the propellants are stored in separate tanks. The fuel density indicated is the average for the MAKS design, which burned 17,850 kg LH2 and 18,698 Kerosene to reach orbit using 175,758 kg of liquid oxygen oxidiser.

Liquid oxygen, as normally supplied, is of 99.5 percent purity and is covered in the United States by Military Specification MIL-P-25508. High purity liquid oxygen has a light blue colour and is transparent. It has no characteristic odour. Liquid oxygen does not burn, but will support combustion vigorously. The liquid is stable; however, mixtures of fuel and liquid oxygen are shock-sensitive. Gaseous oxygen can form mixtures with fuel vapours that can be exploded by static electricity, electric spark, or flame. Liquid oxygen is obtained from air by fractional distillation. The 1959 United. States production of high-purity oxygen was estimated at nearly 2 million tonnes. The cost of liquid oxygen, at that time, ex-works, was $ 0.04 per kg. By the 1980's NASA was paying $ 0.08 per kg.

Rocket propellant RP-1, or its foreign equivalents, is a straight-run kerosene fraction, which is subjected to further treatment, i.e., acid washing, sulphur dioxide extraction. Thus, unsaturated substances which polymerise in storage are removed, as are sulphur-containing hydrocarbons.

Fuel: Kerosene/LH2. Propellant Formulation: Lox/Kerosene/LH2. Optimum Oxidizer to Fuel Ratio: 4.8. Density: 0.50 g/cc. Fuel Density: 0.133 g/cc. Fuel Freezing Point: -259 deg C. Fuel Boiling Point: -253 deg C.

Tripropellant. Figures indicated are average for RD-701 engine.

Specific impulse: 440 s.

More... - Chronology...

Associated Engines
  • RD-0120TD Kosberg tri-propellant (lox/lh2/kerosene) rocket engine. 1317 kN. Developed 1990's. Isp=419 / 452s. Experimental version of the RD-0120 engine. Tested by supply of high-pressure kerosene from test bench or adapted existing kerosene pump for tests. More...
  • RD-0750 Kosberg lox/lh2/kerosene rocket engine. 1412 kN. Alternative for Angara central stage, MAKS. Developed 1997-. Isp=455s. Tripropellant derivative of RD-0120. Some components tested in RD-0120TD technology demonstration in cooperation with Aerojet. More...
  • RD-701 Glushko lox/lh2/kerosene tripropellant rocket engine for air-launched MAKS spaceplane. 4003 kN. Development ended 1988. Isp=415 / 460s. First flight 2001. More...
  • RD-704 Glushko Lox/Kerosene/LH2 tripropellant engine. 1966 kN. Developed 1990's. Isp=407 / 452 s. Tripropellant engine, single chamber, derived from RD-701 project. Chamber pressure 294 / 124 bar. First flight 1999. More...

Associated Stages
  • MAKS Orbiter Lox/Kerosene/LH2 propellant rocket stage. Loaded/empty mass 18,600/18,600 kg. Thrust 3,618.77 kN. Vacuum specific impulse 437 seconds. Empty mass without 9300 kg payload. More...

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