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liquid propellant
A propellant used in a liquid-propellant rocket engine.
Three main categories of liquid propellants may be distinguished:
Additionally, liquid propellants may be classed as bipropellants (in which a liquid fuel and a liquid oxidizer are stored separately) or monopropellants.A good liquid propellant is one with a high specific impulse. This implies a high combustion temperature and exhaust gases with small molecular weights. However, another important factor is the density of the propellant. Lower density propellants require larger storage tanks, thus increasing the mass of the launch vehicle. Storage temperature is also important. A propellant with a low storage temperature, i.e. a cryogenic, requires thermal insulation, thus further increasing the mass of the launcher. The toxicity of the propellant yet another consideration. There are safety hazards in handling, transporting, and storing highly toxic compounds. Also, some propellants are very corrosive, however, materials that are resistant to certain propellants have been identified for use in rocket construction.
| PROPERTIES OF LIQUID ROCKET PROPELLANTS | |||||
|---|---|---|---|---|---|
| compound |
chemical formula |
molecular weight |
density |
melting point |
boiling point |
O2 |
32.00 |
1.141 g/ml |
-218.8 °C |
-183.0 °C |
|
N2O4 |
92.01 |
1.45 g/ml |
-9.3 °C |
21.15 °C |
|
HNO3 |
63.01 |
1.55 g/ml |
-41.6 °C |
83 °C |
|
H2 |
2.016 |
0.071 g/ml |
-259.3 °C |
-252.9 °C |
|
N2H4 |
32.05 |
1.004 g/ml |
1.4 °C |
113.5 °C |
|
CH3NHNH2 |
46.07 |
0.866 g/ml |
-52.4 °C |
87.5 °C |
|
dimethyl hydrazine |
(CH3)2NNH2 |
60.10 |
0.791 g/ml |
-58 °C |
63.9 °C |
C12H26 |
170.34 |
0.749 g/ml |
-9.6 °C |
216.3 °C |
|
Related category
• PROPELLANTS
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