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Monomethylhydrazine (MMH) is a highly toxic, volatile hydrazine derivative with the chemical formula CH 6 N 2. It is used as a rocket propellant in bipropellant rocket engines because it is hypergolic with various oxidizers such as nitrogen tetroxide (N 2 O 4) and nitric acid (HNO 3). As a propellant, it is described in specification MIL-PRF ...
The most common hypergolic fuels, hydrazine, monomethylhydrazine and unsymmetrical dimethylhydrazine, and oxidizer, nitrogen tetroxide, are all liquid at ordinary temperatures and pressures. They are therefore sometimes called storable liquid propellants. They are suitable for use in spacecraft missions lasting many years.
Draco are hypergolic liquid-propellant rocket engines that utilize a mixture of monomethyl hydrazine fuel and nitrogen tetroxide oxidizer. Each Draco thruster generates 400 newtons (90 lbf) of thrust. [26] They are used as Reaction Control System (RCS) thrusters on both the Dragon spacecraft, and on the Falcon 9 launch vehicle second-stage. [27]
Nitrous oxide fuel blend propellants are a class of liquid rocket propellants that were intended in the early 2010s to be able to replace hydrazine as the standard storable rocket propellent in some applications. In nitrous-oxide fuel blends, the fuel and oxidizer are blended and stored; this is sometimes referred to as a mixed monopropellant.
Dual mode propulsion systems combine the high efficiency of bipropellant rockets with the reliability and simplicity of monopropellant rockets. [1]Dual mode systems are either hydrazine/nitrogen tetroxide, or monomethylhydrazine/hydrogen peroxide (the former is much more common).
Draco thrusters generate 400 newtons (90 pounds-force) of thrust using a storable propellant mixture of monomethyl hydrazine fuel and nitrogen tetroxide oxidizer.The Draco thrust is comparable to the Marquardt R-4D engine developed for the Apollo Service and Lunar Modules in the 1960s and used for apogee/perigee maneuvers, orbit adjustment, and attitude control.
There is no igniter with hydrazine. Aerojet S-405 is a spontaneous catalyst, that is, hydrazine decomposes on contact with the catalyst. The decomposition is highly exothermic and produces a 1,000 °C (1,830 °F) gas that is a mixture of nitrogen, hydrogen and ammonia. The main limiting factor of the monopropellant rocket is its life, which ...
The highest-specific-impulse chemistry ever test-fired in a rocket engine was lithium and fluorine, with hydrogen added to improve the exhaust thermodynamics (all propellants had to be kept in their own tanks, making this a tripropellant). The combination delivered 542 s specific impulse in vacuum, equivalent to an exhaust velocity of 5320 m/s.