4. ROCKET PROPULSION
• It is the propulsion of an aircraft
by the reaction of gases coming
out with high velocity.
• Since the altitude of the rocket
engine is very high, enough air is
not available at the surrounding
atmosphere for combustion
• Hence a separate tank is filled
with oxygen and another tank is
filled with fuel.
JET PROPULSION ROCKET PROPULSION
1 Oxygen is obtained from
for combustion purposes
It consists of its own
oxygen supply for
2 Jet consists of air plus
the combustion products
Jet consists of exhaust
3 Altitude limitation No altitude limitation
4 Thrust decreases with
Thrust improves slightly
5 Rate if climb decreases
Rate of climb increases
6 Mechanical devices are
Mechanical devices are
6. Classification of Rocket
Classification based on fuel used:-
Chemical rockets: Heat energy developed
during combustion is used to propel the
Nuclear rockets: Heat energy generated by
fission and fusion processes are used to
propel the rocket.
Solar rockets: Heat energy derived from
sun is used to propel the rocket
Electrical rockets: Rockets powered by
electrical motors with the help of battery
or solar cells.
7. Classification of Rocket
Classification based on propellants used:-
Liquid propellant rockets
Solid propellant rockets
Classification based on number of stages:-
Single stage rockets
Classification based on size and ranges:-
Short range rockets
Long range rockets
8. Classification of Rocket
Classification based on its application:-
Weather forecasting rockets
Military rockets (spying rockets and missiles)
Space exploration rockets
Booster rockets(Multistage rockets – Generally
used to elevate the main rocket to a greater
Retainer or sustainer rockets – They are small
rockets which impart low thrust for long duration
for additional energy supply to space vehicles,
Retro rockets – fired in opposite direction to
decrease the speed of a main rocket like braking
10. Solid Propellant Rockets
Uses solid fuel and oxidizers (propellant)
Solid fuel( plastic or resin material)
Oxidizer(Per chlorates, nitrates)
Both are mixed in single propellant and
packed inside the shell.
When ignitor ignites, combustion starts.
A liner is provided between the shell and
propellant to protect from high temp.
After combustion, the exhaust gas comes
out with high velocity.
♣Simple in design and construction
♣Free from moving system such as pumps,
turbines, hence pay load capacity is high.
♣Density of fuel is high, therefore large
quantity of fuel is packed into small space.
♠Decrease in speed is not possible because
combustion cannot be stopped in midway.
♠Nozzle erosion decreases nozzle life
♠Nozzle cooling is not possible
Solid Propellant Rockets
14. Liquid Propellant Rockets
Uses liquid fuel and oxidizers (propellant)
Liquid fuels( liquid hydrogen,UDMH,
hydrazine, alcohol, etc)
Oxidizer(liquid oxygen, liquid fluorine, red
fuming nitric acid (RFNA).
Fuel and oxidizers are stored separately.
The mixture is at low temperature(-150⁰C –
100⁰C) is preheated and injected in the
Combustion temperature is very high and
thrust propels in the opposite direction.
♥Engines can be reused after recovery.
♥Speed regulation, i.e., increase or decrease
in speed is possible by control of fuel valve.
♥High specific impulse (Thrust/Wgt flow rate)
♦Construction is more complicated
♦Low pay load capacity.
♦Liquid propellant are poisonous and
corrosive, hence careful handling needed.
♦Density is low, hence more volume space is needed
Liquid Propellant Rockets
18. Hybrid Propellant Rockets
Combination of liquid and solid propellants.
Fuels: Beryllium hydride, Lithium hydride, polythene
Oxidizer: Chlorotrifluorine, nitrogen tetra oxide
Liquid oxidizer is stored in a separate tank
is pumped through a valve and injected into
combustion chamber (solid fuel present).
When fuel and oxidizer mixes together,
combustion takes place automatically.
After combustion, the high temperature
exhaust gases are expanded through the
nozzle and propels the rocket
Pay load capacity is more
Reduction in speed is possible
Solid fuel is compact and more mass of fuel
can be stored.
Light wgt compared to liquid propellant
In case of accident or crash the explosion
is less compared to liquid propellant rocket
Nozzle erosion cannot be avoided.
Hybrid Propellant Rockets
20. Monopropellants: A liquid propellant which
contains both the fuel and oxidizer in a
e.g., Hydrazine, nitroglycerine, nitromethane,
hydrogen peroxide, etc.,
A liquid propellant which contains the fuel
and oxidizer in separate units.
23. It should release large amount of heat
Physical and chemical properties should not
change during processing
It should have high density.
It should not be poisonous and hazardous.
It should be cheap and easily available.
It should be non-corrosive and non reactive
with components of the engine
Storage and handling should be easy.
Properties of Solid propellants
24. Must have higher thermal conductivity.
It should have higher calorific value
Density of propellant must be high, hence
they require smaller tank
It should not chemically react with motor
system including tanks, piping, valves, etc.,
Combustion must have lower molecular
weight to produce high jet velocity and
Must be able to produce high chamber
Properties of liquid
25. RATO or JATO
When the aircraft power is not
sufficient for take off, rockets
(integral part of aircraft) are fired
to augment the power of the rocket
engine. This method of take off is
known as RATO or JATO
RATO – Rocket Assisted Take Off
JATO – Jet Assisted Take Off
26. Used in aircrafts as propulsion .
Used in missile in military
Used as a space vehicle or
Used as a space flights
Used for scientific investigations
Used for weather prediction
Used for communication networks.
Application of rocket engines
27. There are two types of liquid feed system
Gas Pressure feed system
Pump feed system
Combustion of a liquid propellant(Fuel and
oxidizer mixture) in the combustion
chamber requires the following basic
1. Injection 2. Atomization 3. Mixing 4.
Vapourization 5. Ignition 6. Chemical reaction
between fuel and oxidizer
liquid propellant feed System
29. An inert gas(Helium or Nitrogen) is stored in a
tank at high pressure and it is passed into
pressure-regulator valves. This high pressure
inert gas from the regulator is used to force
the propellants(fuel and oxidizer)
The propellants under high pressure are forced
to flow into the combustion chamber through
Several regulating and check valves are used
for filling, draining and checking the flow of
Moving parts such as pumps and turbines are
The pressurization of the propellant tank is
heavier, hence this system is not suitable for
large rocket engines and long range missions.
GAS PRESSURE FEED SYSTEM
31. In this system, liquid fuel and the liquid oxidizer
are stored in a separate tank at low pressure.
Liquid fuel and liquid oxidizer are forced into the
combustion chamber at high pressure by the fuel
and oxidizer pumps.
Gas turbine is used to operate the fuel and oxidizer
Liquid hydrogen peroxide (H2O2) from the tank is
decomposed by a catalyst such as calcium or sodium
permanganate. Due to this, steam and oxygen are
generated. This steam is used to drive the turbine.
Because of the third liquid, the gas turbine, the
pumps and additional lines are necessary. So the
pump pressurization system is considerably more
complex than gas pressurization system.
Design of pump is a greatest problem that will
handle the liquids safely and without leaks.
TURBO PUMP FEED SYSTEM