/sci/ - Science & Math

Just learned about pic related, why don't we see tripropellent based engines if you can make them so much better?

>>14634625
>The RD-701 is a tripropellant engine that uses a staged combustion cycle with afterburning of oxidizer-rich hot turbine gas.
>The RD-701 has two modes. Mode 1 uses three components: LOX as an oxidizer and a fuel mixture of RP-1 / LH2 which is used in the lower atmosphere. >Mode 2 also uses LOX, with LH2 as fuel in vacuum where atmospheric influence is negligible.
> The 'RD-701' is a two chamber engine. It can operate in two modes. In the first, it burns both kerosene and hydrogen, granting it greater thrust and impulse density, allowing for smaller, lighter tanks. In the second, it burns only hydrogen, allowing for greater specific impulse. The RD-701 has two preburners per combustion chamber, both of which run oxygen rich. One is used to pump kerosene and oxygen, the other is used to pump hydrogen and oxygen.
>In mode one, both burn kerosene. Liquid hydrogen is combined with kerosene and oxygen rich preburner exhaust in the combustion chamber. In this mode, it produces 4 MN of thrust, with a vacuum specific impulse of 415s, using 73.7 kg/s of kerosene, 29.5 kg/s of hydrogen, and 388.4 kg/s of oxygen.
>In mode two, the preburner used to pump kerosene is shut down, and the other is switched to burning hydrogen. A small amount of kerosene is still used to ensure oxygen is effectively atomised. Gases from the preburner combined with hydrogen in the combustion chamber. In this mode it burns 27.4 kg/s of hydrogen, and 148 kg/s of oxygen. Thrust reduces to 1.6 MN, and specific impulse increases to 460s