bipropellantssuch

Bipropellants are a type of rocket propellant consisting of two components: a fuel and an oxidizer. Both the fuel and oxidizer are stored separately and are only mixed and ignited in the combustion chamber. This separation is key to the operation of bipropellant rockets, as it allows for long-term storage of the propellants without spontaneous reaction. When the two components are brought together, they react exothermically, producing a large volume of hot gas that is expelled through a nozzle to generate thrust.

The choice of fuel and oxidizer combinations is vast and depends on factors such as performance requirements, cost, storability, and safety. Common fuels include hydrazine, monomethylhydrazine (MMH), unsymmetrical dimethylhydrazine (UDMH), kerosene (RP-1), and liquid hydrogen. Oxidizers often used are nitrogen tetroxide (NTO), nitric acid, and liquid oxygen (LOX). Some bipropellant combinations are hypergolic, meaning they ignite spontaneously upon contact, simplifying engine design by eliminating the need for an ignition system.

Bipropellant rockets are widely used in space missions due to their high specific impulse, which is a measure of their efficiency. They are employed in various applications, including orbital maneuvering, spacecraft propulsion, and satellite station-keeping. The ability to throttle the thrust by controlling the propellant flow also makes bipropellant engines versatile for different mission phases. Compared to monopropellant systems, bipropellants offer significantly more energy and thus greater performance.