Rockets_and_how_they_work

1. Rockets and how they work
By Jan-Erik Rønningen
Norwegian Rocket Technology
[ contact@rocketconsult.no ]
[ www.rocketconsult.no ]
Version: 1.30 2008

2. Contents
 Rocket history
 Rocket Principle
 Fundamental Rocket Elements
 The Solid Propellant Rocket
 The Liquid Propellant Rocket
 The Hybrid Rocket Motor

3. Rocket History 1
 The Chinese is claimed by many to be the
inventor of the black powder (about 200
B.C) and thus the rockets
 Newer findings indicate that it is India that
should be honored instead
 However, old Chinese documents describe
long tradition in making various black
powder charges for use in firecrackers and
rockets mostly for frighten bad spirits during
religious happenings and during various
festivals and celebrations.
 The Chinese also developed rockets and
flame torches to be used in combat against
their main enemy, the Mongols.

4. Rocket History 2
 The Arabs learned the art of rocketry
from the Mongols and the Europeans
from the Arabs.
 The Europeans developed the rocket
technology further, i.e. between the
14th and 16th century:
 A English munch named Roger
Beacon improved the black powder
prescription for use as rocket
propellant, fire crackers and for use in
canons.
 A French man improved the hit
accuracy of his artillery rockets by
launching them from tubes.
 An Italian (Fontana) experimented
with rocket powered surface
torpedoes which could ran into the
cavalry or set ships on fire. One
successfully did!!

5. Rocket History 3
 The interest of the rocket as a weapon
went into a hibernation during the 17th
century, mainly because of the poor
accuracy compare to the more
accurate and destructive canon.
Further improvements were
necessary.
 A new dawn of rocketry appeared
during the 18th century and especially
some hundred years after Sir Isacc
Newton had published his famous
three laws.
 During the 19th and 20th century
many men were to become well know:
Ziolkowsky, Hermann Oberth, Robert
H. Goddard, Eugen Sänger, Werner
von Braun, Korolev and many more

6. Rocket History 4
 After the WWII the race for space
between USA and former Soviet
escalated and accelerated the
development of rocket technology to
what we know and use today.
Sputnik I – World first artificial
satellite launched 4. October 1957
Apollo 11 and Neil Armstrong –
First man on the Moon
20. July 1969
Vostok 1 and Yuri A, Gagarin –
First man in space
12. April 1961

7. The Rocket Principle 1
Newtons 2. law:
Newtons 3. law: force = opposite force
 


 a
m
dt
v
m
d
F
)
(
Rocket
dt
dp






Exhaust
dt
dp






dt
v
m
d
dt
dp exhaust
Rocket
)
( 








8. The Rocket Principle 2
 A chemical rocket is a reaction device
that brings with itself the oxygen
needed for combustion and thus for
generating thrust for positive
propulsion

9. Rocket Elements – Main Parts
Convergent Divergent
section section
t e
i
c
Ve
Vt
Vc
c : chamber
i : entrance
t : throat
e : exit
V: velocity
F

10. Rocket Elements - Thrust
impulse
exhaust
exhaust
exhaust
exhaust
products
reaction
rocket
F
v
m
v
dt
dm
dt
v
m
d
dt
dp




















 
_
)
(
Ambient Pressure
Ambient Pressure
Ambient Pressure
Exit Pressure
)
(
_ a
e
e
e
force
pressure P
P
A
P
A
F 





)
(
_ a
e
e
e
force
pressure
impulse P
P
A
v
m
F
F
F 







F

11. Rocket Elements - Nozzle Flow
[4]
or
0
:
expression
above
the
ting
Differenta
const.
ln
ln
ln
:
eq.1
of
logaritm
natural
the
now take
we
proceeding
Before
[3]
:
as
written
be
can
2
eq.
flow,
l
dimensiona
-
one
and
change
potential
no
assume
we
Since
height
:
z
and
)
(
weight
specific
:
speed,
:
v
density,
:
pressure,
:
p
:
where
line)
stream
a
along
(const.
[2]
0
)
(
5
.
0
:
friction)
no
(assuming
equation
Bernoulli
famous
the
to
leading
flow,
particle
fluid
steady
a
describe
to
utlilized
be
can
law
second
Newtons
[1]
.
:
states
mass
of
on
conservati
the
conduit,
a varying
gh
flow throu
fluid
a
When
2
2
A
dA
d
v
dv
v
dv
A
dA
d
v
A
v
dv
v
dp
g
dz
v
d
dp
const
v
A
m




































 
 
0!
dA/dv
1,
Ma
When
[10]
1
dv
dA
:
gives
eq.8
of
g
rearrangin
A
1
Ma
:
flow
Supersonic
1
Ma
:
flow
Subsonic
:
conclude
can
we
which
From
[9]
)
1
(
dp
:
us
gives
eq.8
and
4
Eq.
[8]
)
1
(
1
v
dv
:
form
to
eq.7
with
merged
be
further
can
3
Eq.
[7]
1
:
as
written
be
6
eq.
now with
can
5
Eq.
[6]
and
:
density
with
pressure
of
s
variation
to
related
is
sound
of
speed
the
less),
friction
and
(adiabatic
flow
isentropic
assume
We
[5]
1
:
gives
[4]
[3]
2
2
2
2
2
2
2
2













































Ma
v
A
Ma
Ma
A
dA
Ma
A
dA
A
dA
Ma
v
dp
a
v
Ma
p
a
A
dA
d
dp
v
v
dp
s





Flow
Flow

12. Pe>Pa (under expansion)
Rocket Elements - Nozzle Flow
M~0 M=1 M>3
P=Pk Ph~0.5Pk Pe
Subsonic Transonic Supersonic
Pe=Pa (optimum expantion)
Pe<Pa (over expansion)
Entrance Throat Exit

13. Rocket Elements - Nozzle Flow
0.15 0.2 0.25 0.3
X-posisjon
-0.05
0
0.05
Y-posisjon
AM
3.4
3.2
3.0
2.8
2.6
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Laval dyse, ekspansjonsforhold=8.3
Machtall konturer [-]

14. Rocket Elements - Total Impulse
0,00
5000,00
10000,00
15000,00
20000,00
25000,00
30000,00
35000,00
0,000 1,000 2,000 3,000 4,000 5,000 6,000 7,000
Time (s)
Thrust
(N)
b
tb
t t
F
dt
t
F
I 


 
0
)
(

15. Static Firing a Rocket Motor
NSR 30kN Hybrid Rocket Motor, 20s test

16. Rocket Elements - Specific Impulse
Specific Impuls Values for Various Chemical Propellants
830
1442 1470
1825 1880
2200
2600 2630
3240
3796
10000
0
2000
4000
6000
8000
10000
12000
75% KNO3 +
15% S +
10% C
H2O2 +
KMnO4
65% KNO3 +
35%
C6H14O6
75% KClO4
+ 17.5%
Asphalt +
7.5% Oil
82%
NH4NO3 +
11% HTPB +
7% Additives
60% NG +
40% NC
78%
NH4ClO4 +
15% HTPB +
7% AL
RFNA + RP1 LO2 + HTPB LO2 + LH LH2 + U235
Specific
Impuls
[Ns/kg]
Non Chemical
Rocket Propellant Condition Exampel of Use ISP [Ns/kg]
Black Powder (75%KNO3 + 15%S + 10%C) Pressed Powder Fireworks 830
Hydrogen Peroxide H2O2(l) + Potassium Permanganat KMnO4(s) Liquid/Solid Hobby Rockets 1442
Candy Propellant (65%KNO3 + 35%C6H14O6) Hot Casted Hobby Rockets 1470
75% KClO4 + 17.5% Asphalt/Tar + 7.5% Oil Casted Hobby Rockets 1825
82% NH4NO3 + 11% HTPB + 7% Additives Casted Gassgenerator 1880
Double Base (60% Nitroglycerine + 40% Nitrcellulose) Extruded Missiles 2200
78% NH4ClO4 + 15% HTPB + 7% Al Casted Ariane 5 SRB 2600
RFNA + Kerosene (RP1) (1.43 Mixtureratio) Liquid X-1 Rocket Plane 2630
LOX + HTPB Liquid/Solid Launch Vehicle 3240
LOX + LH (3.40 Mixtureratio) Liquid Ariane 5 1.stage 3796
LH + Solid Core Nuclear Reactor (Fisson of U235) Liquid/Solid Nerva Test Motor 10000
d
b
sp
m
t
F
I



17. The Solid Propellant Rocket
Construction:
Motor Case Thermal Insulation
Propellant Nozzle
Igniter

18. Solid Propellant Rocket
PARAMETER CHARACTERISTIC VALUE RANGE
Specific Impulse [m/s] 2000-2600
Burn rate [mm/s] 1-15
Chamber Pressure [MPa] 7-20
Combustion Efficiency [-] 0.95-0.98
Thrust to Weight Ratio High
Throttle? Difficult
Stop and Restart? Not Practical
Lifetime? Long (7 to 15 years)

19. The Solid Propellant Rocket
Propellant Mixing:
300 gallon  approx. 1200kg of propellant

20. The Solid Propellant Rocket
Propellant Grain Geometry:

21. Advanced Grain Burn Evolution

22. The Solid Propellant Rocket
Ariane 5 Solid Rocket Booster:
DATA for one SRB
Propellant: HTPB
Propellant Mass: 237T
(158 cars)
Motor Mass: 273T
(182 cars)
Thrust: 5400kN (about 550T!!!!)
Burn Time: 130s (2.16min)
Mass Consumption: 1.82T/s
TVC: +/-6deg vectorable nozzle

23. The Liquid Propellant Rocket
Constructions:

24. The Liquid Propellant Rocket
PARAMETER CHARACTERISTIC VALUE RANGE
Specific Impulse [m/s] 2500-3800
Burn Rate [mm/s] N.A
Chamber Pressure [MPa] 2-10
Combustion Efficiency [-] 0.95-0.98
Thrust to Weight Ratio Low
Throttle? Easy
Stop and Restart? Easy
Lifetime? Very Long (> 10 years)

25. The Liquid Propellant Rocket

26. The Liquid Propellant Rocket

27. The Liquid Propellant Rocket

28. The Hybrid Rocket
Nozzle
Combustion Chamber
Pressurized Nitrogen or Helium
Start/stop Valve and pressure
regulator
Valve Electronics
Check Valve Solid Grain
“Mixing” Zone
Injector
Liquid
Flow Valve and Regulator
with control electronics

29. The Hybrid Rocket
PARAMETER CHARACTERISTIC VALUE RANGE
Specific Impulse [m/s] 2100-3200
Regression rate [mm/s] 0.2-5
Chamber Pressure [MPa] 2-5
Combustion Efficiency [-] 0.90-0.95
Thrust to Weight Ratio Medium
Throttle? Easy
Stop and Restart? Easy
Lifetime? Very Long (>10 years)

30. The Hybrid Rocket
Combustion Principle – The Candle Light
Air Air
Paraffin Wax
Liquid
Gas (H, C)

31. The Hybrid Rocket

32. The Hybrid Rocket

33. How is it to work as an “rocket
scientist”?