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About 170 different propellants made of liquid fuel have been tested, excluding minor changes to a specific propellant such as propellant additives, corrosion inhibitors, or stabilizers. In the U.S. alone at least 25 different propellant combinations have been flown. [2] Many factors go into choosing a propellant for a liquid-propellant rocket ...
The propellant used in a rocket engine plays an important role in both engine design and in design of the launch vehicle and related ground equipment to service the vehicle. Weight, energy density, cost, toxicity, risk of explosions, and other problems make it important for engineers to design rockets with appropriate propellants. The major ...
The rocket is launched using liquid hydrogen and liquid oxygen cryogenic propellants. Rocket propellant is used as reaction mass ejected from a rocket engine to produce thrust . The energy required can either come from the propellants themselves, as with a chemical rocket , or from an external source, as with ion engines .
Generally, this is a separate tank of liquid or high-pressure inert gas, such as nitrogen or helium. This adds extra cost and weight. Cryogenic or volatile propellants generally do not need a separate pressurant; instead, some propellant is expanded (often with engine heat) into low-density gas and routed back to its tank. A few highly volatile ...
Liquid rocket engines have tankage and pipes to store and transfer propellant, an injector system and one or more combustion chambers with associated nozzles.. Typical liquid propellants have densities roughly similar to water, approximately 0.7 to 1.4 g/cm 3 (0.025 to 0.051 lb/cu in).
Hydrogen peroxide works best as a propellant in extremely high concentrations (roughly over 70%). Although any concentration of peroxide will generate some hot gas (oxygen plus some steam), at concentrations above approximately 67%, the heat of decomposing hydrogen peroxide becomes large enough to completely vaporize all the liquid at standard pressure.
Liquid propellants provide greater propulsive thrust and power, but require more complex technology and extra weight. Solid fuel is dense and burns quite quickly, generating thrust over a short time.
These cryogenic temperatures vary depending on the propellant, with liquid oxygen existing below −183 °C (−297.4 °F; 90.1 K) and liquid hydrogen below −253 °C (−423.4 °F; 20.1 K). Since one or more of the propellants is in the liquid phase, all cryogenic rocket engines are by definition liquid-propellant rocket engines. [2]