Fundamental of Rockets

1. LIQUID OXIDIZERS

2.  There are different types of liquid oxidizers.
 For high specific impulse:
 boron-oxygen-flourine compounds
 oxygen-flourine compounds
 nitrogen-flourine compounds
are used.

3.  Liquid oxidizers that are used in
experimental rockets are:
i. liquid oxygen and liquid fluorine
ii. Oxygen di-flouride (OF2)
iii. Chlorine triflouride (ClF3)
iv. Chlorine pentaflouride (ClF5)
 All these are very toxic and corrosive

4. Liquid Oxygen
(LOX)
 It is used with alcohols, jet fuels (kerosene),
gasoline and hydrogen.
 It does not burn instantly with organic
materials at surrounding temperature and
combustion occurs when a specific mixture
of oxygen and organic matter is suddenly
pressurized.

5.  Liquid oxygen accelerates the combustion of
other materials.
 It is a non toxic and non corrosive liquid and
will not deteriorate clean container walls.
 Cryogenic propellant cause severe burns to
human skin when exposed to it for long.

6.  As liquid oxygen evaporates quickly so it
cannot be stored for longer period of time.
 Liquid oxygen is produced in different ways
e.g by boiling liquid nitrogen out of liquid
air.

7.  To save evaporation loss insulate all lines,
valves, pipes and tanks that contain liquid
oxygen.
 Liquid oxygen storage system should be
well insulated against absorbing heat from
surroundings.

8. Hydrogen Per Oxide
(H2O2)
 It is been used in high concentration (70-99%)
and the remainder is mostly water.
 In the combustion chamber the propellant
decomposes in the presence of a catalyst as:
heatOOHOH ++→ 2222
2
1

9.  Catalyst could be liquid permanganates,
solid magnesium dioxide, platinum, iron
oxide.
 H2O2 is hypergolic with hydrazine and burns
well with kerosene.
 Specific impulse of 90% H2O2 is 147 sec when
used as a mono propellant.

10.  Contaminated H2O2 must be disposed before it
reaches a damage point of 448K where explosion
occurs.
 It cause severe burns when it becomes in contact
human skin, may ignited cause fire when comes
in contact with woods, oils and many other
organic materials.
 It has not been used for long time due to its long
term storage problem.
 Now there has been some improvement in this
dense oxidizer and produces a non toxic
exhaust.

11. Nitric Acid
(HNO3)
 Between 1940-1965 many types of HNO3
mixtures were used as oxidizers.
 The most common type is red fuming HNO3
(RFNA)
 It consists of concentrated HNO3 with 5-20%
of dissolved nitrogen dioxide.
 The evaporating red-brown fumes are quite
annoying & poisnous

12.  Concentrated HNO3 is also called white
fuming HNO3 (WFNA).
 RFNA as compared to WFNA is more stable
in storage and less corrosive to many tank
materials.
 HNO3 is highly corrosive and only some
kinds of HNO3 are satisfactory to be stored
(stainless steel, gold).

13.  If a small amount of flourine ion is added to
HNO3 it will make a fluoride layer on wall
and reduces the corrosion greatly.
 In case of spilling, HNO3 should be diluted
with water or chemically deactivated
(carbonates, alkali metals, hydroxides are the
common neutralizing agents)

14.  HNO3 has been used with gasoline,
hydrazine and alcohols.
 Specific gravity of HNO3 varies from 1.5 -1.6
depending upon the % of HNO3, water and
impurities.

15. Nitrogen Tetra Oxide
(N2O4)
 They have high density and are yellow
brown liquid.
 They have the specific gravity of 1.44.
 Most commonly used oxidizer in USA for
storage but its liquid temperature is narrow
and can be easily frozen or vaporized.
 When it is pure it’s very little corrosive.

16.  It absorbs moisture from air and can be
stored for longer periods of time in sealed
containers.
 It is hypergolic with many fuels and give
instant ignition with many materials (paper,
leather, wood)
 Reddish brown fumes are very toxic.
 Mixtures of NO and N2O4 gives the mixed
oxides of nitrogen (MON)

17.  Storable propellant oxidizers used in Titan
missile with a mixture of hydrazine and
unsymmetrical dimethyl hydrazine.
 It is used with mono methyl hydrazine fuel
in space shuttle RCS and in propulsion
system of many space crafts.
 Care is needed to avoid freezing of the
propellant